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This manual covers engine models: OHH50 - 65, OHHSK50 - 130, OHV11 - OHV17, OVM120, OVRM40-675, OVRM120, OVXL/C120, OVXL120, OVXL125. Other illustrated Tecumseh 2-Cycle Engine, 4-Cycle Engine and Transmission manuals; booklets; and wall charts are available through Tecumseh. For complete listing write or call CONTAINS SEARS CRAFTSMAN CROSS REFERENCE
C Tecumseh Products Company 1998
Copyright © 1994 by Tecumseh Products Company All rights reserved. No part of this book may be reproduced or transmitted, in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without permission in writing from Tecumseh Products Company Training Department Manager.
2).B.Overhead Valve Horizontal Snow King OVM OVRM . The number following the model number is the specification number.M. OHV Overhead Valve Vertical 16 Indicates the basic engine model. indicates the production date of the engine. serial 5215C as an example. The last three numbers of the specification number indicate a variation to the basic engine specification. specification. 1995).) standards will include additional required engine information on the engine decal. 1 & 2).) are stamped into the blower housing. Using model OHV16-204207A.A.O.Overhead Valve Vertical The number designations following the letters indicate the basic engine model.Overhead Valve Horizontal MediumFrame .M. OHH OHM . 5215C is the serial number or D.Overhead Valve Horizontal . use only Genuine Tecumseh Parts. Interpretation of Model Number The letter designations in a model number indicate the basic type of engine. 204207A is the specification number used for properly identifying the parts of the engine. and serial numbers or date of manufacture (D. interpretation is as follows: OHV16-204207A is the model and specification number.Overhead Valve Vertical Medium Frame Extra Life OHV . (Date of Manufacture) 5 is the last digit in the year of manufacture (1995). EMISSION REGULATIONS FOR ULGE ENGINES AS APPLICABLE FUEL: REGULAR UNLEADED OIL : USE SAE 30 OHV 125 203000A RTP358UIG2RA 358cc (D) 3057D 2 1 .R.) or the Environmental Protection Agency (E. NOTE: To maintain best possible emission performance.O. The serial number or D. ENGINE MODEL NUMBER 1 THIS ENGINE MEETS 1995-1998 CALIF. 215 indicates the calendar day of that year (215th day or August 3. Emissionized engines that meet the California Air Resource Board (C.P.Overhead Valve Vertical Rotary Mower OVXL .Overhead Valve Vertical Medium Frame OHSK . C represents the line and shift on which the engine was built at the factory.CHAPTER 1 GENERAL INFORMATION ENGINE IDENTIFICATION Tecumseh engine model.A. or located on a decal on the engine in locations as illustrated (diag.O. The engine identification decal also provides the applicable warranty code and oil recommendations (diag.M.
FOR WINTER (Below 320F) (0oC) USE SAE5W30 OIL. Be sure original container is marked: A. This time may be extended with the use of a fuel stabilizer like TECUMSEH'S. HIGH QUALITY DETERGENT OIL. Regardless of which of the approved fuels are used. OVXL 120. Operators Manual.B. prolonged winter operation of HH120 model.100 26 720 OHM. have a capacity of 26 oz.SHORT BLOCKS New short blocks are identified by a tag marked S. NOTE: For severe.B. Fuel should not be stored in an engine or container more than 30 days prior to use. MTBE. DO NOT USE SAE10W40 OIL.564A SER 5107 SERIAL NUMBER FUELS 3 Tecumseh Products Company strongly recommends the use of fresh.V. additives or stabilizers containing methanol.OHSK 50-70 21 630 OVRM 40 . Unleaded gasoline burns cleaner.17 without oil filter 55 1650 OHV 13. unleaded premium or reformulated gasoline containing no more than 10% Ethanol. service "SF" thru "SJ" or "CD". SBV OR SBH IDENTIFICATION NUMBER SHORT BLOCK IDENTIFICATION TAG SBV. high load applications. ml. (Short Block Horizontal) or S. PART #730226 (SAE 10W is an acceptable substitute.) (BELOW 00F (-18oC) ONLY): SAE 0W30 is an acceptable substitute.13 with filter 39 1170 OHV 13.6. Leaded fuel is generally not available in the United States and should not be used if any of the above options are available. FOR SUMMER (Above 320 F) (0oC) USE SAE30 OIL. FOLLOW ALL INSTRUCTIONS.5 -17 2 5/8" filter (part # 36262) 64 1920 * NOTE: Model OHSK110 with a spec. Capacities Engine Model Oz. THIS SYMBOL POINTS OUT IMPORTANT SAFETY INSTRUCTIONS WHICH IF NOT FOLLOWED COULD ENDANGER THE PERSONAL SAFETY OF YOURSELF AND OTHERS. Unleaded regular.13 without oil filter 32 960 OHV 11 . Never use gasoline. white gas. or ETBE because engine/fuel system damage could result. 3). Using multigrade oil may increase oil consumption.I.) 2 . SAE10W oil is recommended. part number 730245. 125 32 960 OHV 11 .75 21 630 OVRM105 & 120 21 630 OHSK80 .H. fuel quality is critical to engine performance. clean. ENGINE OIL TECUMSEH FOUR CYCLE ENGINES REQUIRE THE USE OF A CLEAN. PART #730225 Use SAE30 oil in high temperature. (720 ml. TECUMSEH RECOMMENDS USING ONE OF THE FOLLOWING FOUR CYCLE OILS THAT ARE SPECIALLY FORMULATED TO TECUMSEH SPECIFICATIONS.5 .5 -17 2 1/4" filter (part # 36563) 62 1860 OHV 13. Original model identification numbers of an engine should always be transferred to a new short block for correct parts identification (diag.130 32 960 OVM 120. See "STORAGE" instructions in the Technician's Manual. OHSK 110* . (Short Block Vertical). OHH. or 15% MTBE. fuel conditioners. or 15% ETBE may also be used. or Bulletin 111. or fuel blends which exceed the limits specified above for Ethanol.P. unleaded regular gasoline in all Tecumseh Engines. extends engine life. and promotes good starting by reducing the build up of combustion chamber deposits. of 221000 and up.
or more often if operated under dusty or dirty conditions. cylinder cooling fins. Remove the blower housing and clean all dirt. Contact your local governing authorities to find a waste oil disposal site. grass or debris from the intake screen. consult the proper parts breakdown for the spark plug to be used in the engine being serviced. Always check fuel as a primary cause of poor engine performance. TUNE-UP PROCEDURE: NOTE: Today's fuels can cause many problems in an engines performance due to the fuels quality and short shelf life. Properly reinstall the blower housing. CAUTION: Remove the spark plug wire before doing any service work on the engine. OHV13. 3 . If the engine is run less than 25 hours per year. STANDARD OHV CAUTION: Remove the spark plug wire before doing any service work on the engine. 7. Once the oil is drained. head. Replace any worn or damaged governor springs or linkage. When replacing the spark plug. change the oil at least once per year. start the engine. 1. and use a spark plug wrench to turn the spark plug 1/8 to 1/4 turn further if using the old spark plug. 3.030") (. Make sure all remote cables are properly adjusted for proper operation. fuel line. Other units drain at the base of the engine above the deck or frame. Set the proper spark plug gap (. or 1/2 turn further if using a new spark plug. Always make sure that drain oil is disposed of properly. and air cleaner assembly if removed. reinstall the drain plug and fill the engine with new oil to the proper capacity. gas tank. 9. Oil Change Procedure: Locate the oil drain plug. Make sure the fuel tank. governor levers and linkage. Further repairs may be necessary if the engine's performance remains poor. On some rotary mower applications. The following is a minor tune-up procedure. Inspect the level and condition of the oil and change or add oil as required. 8. Tighten the spark plug to 21 foot pounds (28 Nm) of torque. carburetor. PLUG 4. NOTE: The oil filter (if equipped) requires changing every 100 hours or more often if operated under dusty or dirty conditions. Service or replace the air cleaner. it may be necessary to drain the oil by tipping the mower in a position that would allow the oil to drain out of the fill tube.5-17 every 50 hours). remove the plug and allow the oil to drain into a proper receptacle. Position the equipment so the engine is level when checking the oil.762 mm) and install the spark plug in the engine. 6. On some units this plug is located below the deck through the bottom of the mounting flange. Make sure all ignition wires are free of abrasions or breaks and are properly routed so they will not rub on the flywheel. If a torque wrench isnt available. fuel filter and fuel 4 line are clean. where access to the drain plug is restricted by the equipment. Reinstall the spark plug wire. Oil Check: Check the oil each time the equipment is used or every five (5) hours of operation. When this procedure is completed. add fuel and oil as necessary. Make the proper governor adjustments and carburetor presets where required. screw the spark plug in as far as possible by hand. See Chapter 4 under "Speed Controls and Linkage". 2. See Chapter 2 under "Service". 5. On units that the drain plug is accessible. the engine should operate properly.Oil Change Intervals: Change the oil after the first two (2) hours of operation and every 25 hours thereafter (OHH & OHSK50-130.
Remove all gasoline from the fuel tank by running the engine until the engine stops. the carburetor may be drained by loosening the bowl nut on the bottom carburetor one full turn. On carburetors without a bowl drain. Clean Engine: Remove the blower housing and clean all dirt. complete the above procedure and then put one half pint of unleaded gasoline into the fuel tank and repeat the above procedure. 3. Remove the spark plug and put a 1/2 ounce (15 ml. Run the engine at least 10 minutes after adding the stabilizer to allow it to reach the carburetor.STORAGE (IF THE ENGINE IS TO BE UNUSED FOR 30 DAYS OR MORE) CAUTION: NEVER STORE THE ENGINE WITH FUEL IN THE TANK INDOORS OR IN ENCLOSED. Install the spark plug and connect the spark plug wire. Allow to completely drain and retighten the bowl nut being careful not to damage the bowl gasket when tightening. To prevent deposits from forming. SPARK OR PILOT LIGHT AS ON A FURNACE. grass or debris from the intake screen. Gasoline can become stale in less than 30 days and form deposits that can impede proper fuel flow and engine operation. 1. head. governor levers and linkage. is by adding Tecumseh's fuel stabilizer. Be careful not to damage the fuel line. An acceptable alternative to removing all gasoline. POORLY VENTILATED AREAS. Drain the carburetor by pressing upward on bowl drain (if equipped) which is located on the bottom of the carburetor bowl. Oil Cylinder Bore 1. 4 . all gasoline must be removed from the fuel tank and the carburetor. carburetor. slowly. Fuel stabilizer is added to the fuel tank or storage container. fittings.) of clean engine oil into spark plug hole. Disconnect the spark plug wire and ground the spark plug wire to the engine. the alcohol content can cause rubber gaskets and seals to deteriorate. AND AWAY FROM ANY OPEN FLAME OR COMBUSTION SOURCE. Always follow the mix ratio found on the stabilizer container. this is a good time to do it. If "Gasohol" has been used. If Gasohol is allowed to remain in the fuel system during storage. several times. Cover the spark plug hole with a shop towel. to the gasoline. Draining the Fuel System CAUTION: DRAIN THE FUEL INTO AN APPROVED CONTAINER OUTDOORS. or by draining the fuel tank by removing the fuel line at the carburetor or fuel tank. Crank the engine over. See "Oil Change Procedure" on page 3. or fuel tank. part number 730245. 4. CLOTHES DRYER OR OTHER GAS APPLIANCE. 3. Change Oil: If the oil has not been changed recently. WHERE FUEL FUMES MAY REACH AN OPEN FLAME. WATER HEATER. cylinder cooling fins. BE SURE THE ENGINE IS COOL. 2. 2.
KLEEN-AIRE® ENTRANCE FROM UNDER BLOWER HOUSING POLYURETHENE WRAP PAPER ELEMENT AIR CLEANER BODY 2 5 . Snow King® engines do not use an air filter due to the clean operating environment and to prevent filter freeze-up. and the polyurethane or paper filter element. Dirt allowed into the engine will quickly wear the internal components and shorten the life of the engine. Dry-type paper elements are pleated paper for increased surface area and rubberized sealing edges. AIR CLEANER BODY FLOCKED SCREEN 1 COVER COMPONENTS The cover holds the filter element and prevents large debris from entering the filter body. The polyurethane wrap pre-cleaner is used on XL or XL/C engine models with paper filter elements.CHAPTER 2 AIR CLEANERS GENERAL INFORMATION The air cleaner is the device used to eliminate dust and dirt from the air supply. In Tecumseh's Kleen Aire® system. Air is filtered through the pre-cleaner or flocked screen if equipped. Filtered air is necessary to assure that abrasive particles are removed before entering the combustion chamber. A polyurethane precleaner or a flocked screen may be used with the main filter. Pre-cleaners or flocked screens provide more air cleaning capacity. The paper or polyurethane filter element is the main filter to trap dust and dirt. Tecumseh engines use either a polyurethane or a paper-type air filter system. Extremely dirty conditions may require more frequent filter cleaning or replacement. COVER KLEEN-AIRE® ENTRANCE FROM UNDER BLOWER HOUSING FOAM ELEMENT OPERATION The air cleaner cover allows access to the air filter element(s) and prevents large particles from entering the filter body. The flocked screen is used as an additional filter on XL or XL/C engine models that use a polyurethane filter element. The polyurethane filter uses an oil film to trap fine particles found in dust. air is drawn in through a rotating screen or recoil housing to be centrifugally cleaned by the flywheel before the air enters the air filter.
7. 5. remove the air cleaner assembly from the carburetor before removing the flocked screen. SERVICE Service on the polyurethane filter element (cleaning and oiling) is recommended every three (3) months or every twenty five (25) operating hours. A paper-type air filter should only be replaced. The paper filter element should be replaced once a year or every 100 operating hours. whichever comes first. make sure the seam is installed to the outside to prevent gaps between the paper element and the pre-cleaner. A paper-type filter cannot have an oil film present on the paper. KLEEN-AIRE® ENTRANCE FILTER A (FOAM) WING NUTS COVER GASKET NUTS FILTER B BODY COVER GASKET FOAM FILTER KLEEN-AIRE® ENTRANCE FLOCKED SCREEN GASKET 3 6 . A dirt restricted or an oil soaked filter will cause noticeable performance problems. On air cleaners that use a flocked screen under the polyurethane element. 2. ALWAYS REPLACE THE FILTER ELEMENT WITH THE PROPER TECUMSEH ORIGINAL REPLACEMENT PART. Clean the excess contaminants out of the air cleaner body before removing the old element. Remove the hex nuts holding the element down if equipped. Use reverse procedure for reassembly. 8.TROUBLESHOOTING OR TESTING If the engine's performance is unsatisfactory (needs excessive carburetor adjustments. Follow the procedure listed in the "Service" section of this chapter for filter replacement or cleaning. This prevents dirt from entering the carburetor (diag 3). 4. When installing the polyurethane pre-cleaner. Reinstall the air cleaner assembly using a new gasket. remove the old gasket between the carburetor and the air cleaner assembly. Extremely dirty or dusty conditions may require daily cleanings. A polyurethane filter may be cleaned following the service procedure listed under "Service" in this chapter. 6. loses power). New nuts are supplied with a new filter and are to be used for proper sealing. Unlock the tabs or remove the screws or wing nuts holding the air cleaner cover in place. Remove the old element and the polyurethane pre-cleaner if equipped. Clean the inside of the cover and body. more often if used in extremely dusty conditions. starts smoking abnormally. 3. the first engine component to be checked is the air filter. NOTE: NEVER RUN THE ENGINE WITHOUT THE COMPLETE AIR CLEANER ASSEMBLY INSTALLED ON THE ENGINE. DISASSEMBLY PROCEDURE 1.
COVER COVER KLEEN-AIRE® ENTRANCE FROM UNDER BLOWER HOUSING FOAM ELEMENT POLYURETHENE WRAP PAPER ELEMENT AIR CLEANER BODY AIR CLEANER BODY FLOCKED SCREEN 4 KLEEN-AIRE® ENTRANCE FROM UNDER BLOWER HOUSING 5 7 . The pre-cleaner must not be oiled. Rinse in clear water to remove the detergent solution. 5). Flocked Screen A flocked screen may be cleaned by blowing compressed air through the screen from the backside. Replacement filters are available at any authorized Tecumseh Service Outlet. Do not attempt to clean a paper filter element. Clean the air cleaner housing and cover being careful not to allow dirt to fall into the carburetor or intake pipe. re-oil the filter by applying engine oil and squeezing it vigorously to distribute the oil. If the screen cannot be cleaned with this procedure. Squeeze the filter or pre-cleaner (do not twist) to remove the excess water.Polyurethane-Type Filter Element or pre-cleaner This type of air filter or pre-cleaner can be serviced when restricted with dust or dirt. Wrap the filter or pre-cleaner in a clean cloth and squeeze it (do not twist) until completely dry. Paper -type filter element Paper type air filter elements can only be serviced by replacement. Be sure to use new filter nuts or seals for the air cleaner studs if supplied with the new filter (diag. On the polyurethane filter only. Roll the filter in a cloth and squeeze it (do not twist) to remove the excess oil. it should be replaced with a new screen. Wash the filter or precleaner in a detergent and water solution until all the dirt is removed.
Some Tecumseh engines utilize Walbro carburetors. which decreases the size of the air passage through the carburetor. During HIGH SPEED engine operation. Complete carburetor replacement may be accomplished by a standard service carburetor. further accelerates the air flow. A fuel / air mixture is supplied through the primary idle-fuel discharge orifice during idle. Air flows through the carburetor at high speed. As the starting device is operated to start the engine. Carburetor adjustments. Float type carburetors use a hollow float to maintain the operating level of fuel in the carburetor. use the engine model and specification number to obtain the correct carburetor part number. cleaning. downward piston travel creates a low air pressure area in the engine cylinder above the piston. The throttle is almost completely closed. and the only air entering the engine enters through openings around the shutter. a second orifice is uncovered as the throttle shutter opens. Basic operation is very similar to the Tecumseh float style carburetor. a relatively small quantity of air enters the carburetor at increased speed. 8 . and more fuel mixture is allowed to atomize with the air flowing into the engine. CHOKE PLATE FLAT DOWN 2 At engine IDLE speed. An instruction sheet is provided with the new service carburetor or see SERVICE in this chapter. make a very rich fuel mixture which is needed to start a cold engine. partially adjustable. ALTERNATE LOCATION FOR MANUFACTURING NUMBER 89 4 MANUFACTURING NUMBER F5 89 4F5 CARBURETOR DATE CODE 1 OPERATION In the CHOKE or START position. The float type carburetor will have a fuel enrichment system of either a primer or a manual choke to provide easy cold engine starting. or nonadjustable. the throttle shutter is opened. The main nozzle and both idle fuel discharge ports are supplying fuel due to the low air pressure in the intake of the engine. Higher pressure (atmospheric air) rushes into the engine to fill the created low pressure area. An alternate method to find the correct carburetor part number is to use the manufacturing number stamped on the carburetor and convert this number to a service part number. Carburetors used by Tecumseh can be identified by a manufacturing number stamping on the carburetor as illustrated (diag. Since the majority of the air passage is blocked by the choke shutter. the choke shutter is closed. A maximum fuel flow through the carburetor orifices combined with the reduced quantity of air that passes through the carburetor. During INTERMEDIATE engine operation. This high speed movement of the air decreases the air pressure at the main nozzle opening. a relatively small amount of fuel is required to operate the engine. A standard service carburetor is a basic carburetor that may require the use of original carburetor parts or additional new parts to adapt to the specification. The venturi. When servicing carburetors. and related fuel system service is covered in this chapter. The carburetor fuel mixtures are either fully adjustable. Fuel is forced out the main nozzle opening due the difference in the atmospheric air pressure on the fuel in the carburetor bowl and the reduced air pressure at the main nozzle opening.CHAPTER 3 CARBURETORS AND FUEL SYSTEMS GENERAL INFORMATION Tecumseh overhead valve engines use float type carburetors. 1). a cross reference chart will convert a carburetor manufacturing number to a Tecumseh Service part number. In the carburetor section of the Master Parts Manual or Microfiche Catalog.
This tube must be present for the carburetor to operate properly (diag. the carburetor bowl must be either vented externally or internally. Impulse fuel pumps are operated by crankcase impulses created by the up and down movement of the piston. Atomization occurs as the fuel mixture contacts the fast moving air stream and the mist flows into the intake of the engine. TYGON TUBE INTERNAL VENT EXTERNAL VENT 3 FUEL PRIMERS Primers may be mounted remotely or as an integral part of the carburetor.For the fuel to flow. The basic function of the primer is to supply an air pressure charge to the carburetor main well or carburetor bowl to displace fuel directly into the carburetor venturi. As the fuel is used by the engine. Fuel flows by gravity or a pulse pump into the fuel bowl. As the fuel level in the bowl again rises. This mixes fuel and air prior to the fuel leaving the main nozzle. 7). A crankcase overfilled with engine oil can affect pump operation. it raises the float. 4 & 5). Some internally vented float style carburetors use a tygon tube and a vent within the air intake. the fuel level in the carburetor bowl drops and the float moves downward. 3). Primers must be vented either internally through a passage in the carburetor air horn prior to the venturi or externally through a hole in the primer bulb. The impulses actuate the diaphragm and flap valves to lift the fuel from the fuel tank to the carburetor (diag. This allows the inlet needle valve to move off the sealing seat. 6). This displaced fuel provides a rich mixture necessary for engines to start easily on the first or second attempt (diag. VALVE CLOSED ATMOSPHERIC VENT CARBURETOR FITTING VALVE OPEN DIAPHRAGM FILTER AIR BLEED VALVE OPEN FUEL SUPPLY VALVE CLOSED PULSE LINE TO CRANKCASE FLOW DIRECTION á SUCTION FUEL PRESSURE ATMOSPHERIC ê CAUSED FUEL FLOW êCRANKCASE PRESSURE á ATMOSPHERIC PRESSURE ACTING ON DAMPING DIAPHRAGM á FUEL FLOW ê CRANKCASE SUCTION AND FLOW DIRECTION á ATMOSPHERIC PRESSURE ACTING ON DAMPING DIAPHRAGM 6 FLOAT STYLE CARBURETORS A float is used to maintain the operating level of fuel in the carburetor bowl. When the needle contacts the seat. This upward float motion moves the inlet needle valve to the closed position. The tapered end of the inlet needle varies the fuel flow rate and the fuel level in the carburetor bowl remains constant (diag. PRIMER BULB VENT PRIMER BULB MAIN NOZZLE 4 MAIN JET 5 IMPULSE FUEL PUMPS Impulse fuel pumps may either be mounted externally onto the carburetor fuel inlet or remotely mounted. This pump is connected in the fuel line between the fuel supply and the carburetor or directly to the fuel inlet. The float height is set according to the service procedure. Air is bled into the main nozzle through the air bleed located in the air horn. the fuel flow is stopped. The vent allows atmospheric air to enter the fuel bowl during operation and to fill the primer bulb after the primer bulb is released. A hose called a pulse line connects the fuel pump diaphragm chamber to the crankcase and transmits the impulses to the pump diaphragm. IDLE AIR BLEED MAIN AIR BLEED CHOKE SHUTTER THROTTLE SHUTTER IDLE ADJUSTMENT INLET NEEDLE AND SEAT FLOAT MAIN NOZZLE MAIN ADJUSTMENT 7 9 .
8). The choke shaft is made of a plastic material with an internal slot to hold the choke shutter. The main and idle mixture may be fixed or adjustable.CARBURETOR VISUAL IDENTIFICATION Series1 Carburetors Series 1 carburetors are used on some 4 . To determine whether the carburetor is a Series 3 or Series 4. (diag. The quickest way to identify these carburetors is by the presence of bosses on each side of the idle mixture screw (diag. 10 9 11 Series 6 Carburetors Series 6 carburetors are used on 2 and 4-cycle engines in the 3 to 6 model range. Series 3 will have one throttle plate screw (diag. Series 6 are nonadjustable.7 model overhead valve engines. 9). The Series 4 will have two throttle plate screws (diag. Series 6 carburetors are commonly used on rotary mower applications. Series 6 uses a simple fixed idle and fixed main fuel circuit. The carburetor base is flat to accept a Vector style bowl that is held on with a wire bail. with a stepped primer bulb and a bowl prime system (diag. The die cast carburetor body is similar in appearance and slightly longer than the Walbro LMK body. A remote primer or choke may also be used with this carburetor (diag. 12). 11). 12 Series 7 Series 7 carburetors are totally nonadjustable. 8 Series 3 & Series 4 Carburetors Series 3 or 4 carburetors are generally used on 8 through 14 model 4-cycle engines. look at the throttle end of the carburetor. 13) 13 10 . This float style carburetor has a smaller venturi than the Series 3 or 4 carburetor and has no bosses on each side of the idle mixture screw. 10).
Also visible is a plastic main fuel discharge nozzle in the venturi. The bowl nut uses a ball plug on the bottom to cover the center drilling. These carburetors are totally nonadjustable. LOW IDLE MIXTURE SCREW MAY BE ADJUSTABLE OR FIXED 16 11 . with the added benefit of a choke for cold weather starting. It has a fixed main and idle with a serviceable main nozzle and a primer assist. This fixed idle jet may also be capped. Walbro model and manufacturing numbers are found on the throttle end of the carburetor. The Idle mixing well and jet will be visible but not machined (diag. FLAT SIDE DOWN 15 Walbro Model LMK OHV 15-17 models use this float-feed carburetor. Servicing should be done by a Authorized Tecumseh Dealer. (diag. This has since changed to a fixed idle jet which may be capped for tamper resistance. The carburetor is attached to the intake pipe using studs that also fasten the air filter body. This series of carburetor uses an integral primer system like the Series 6. This carburetor uses a fixed idle jet and fixed main fuel circuit. 14) CAPPED FIXED IDLE JET CAP 14 Series 9 Series 9 carburetors are hybrid versions of the Series 8. This carburetor is totally nonadjustable. It is the equivalent of the series "8" with the addition of a choke. nonadjustable main mixture jet. This carburetor has a fixed. the jet is fixed. Idle mixture screws were adjustable on early production OHV15. If no spring is visible. 15) MIXING WELL CAST BUT NOT MACHINED IDLE JET CAST BUT NOT MACHINED 15 CHOKE PLATE Series 10 This carburetor is for use on all season engine applications. Distinguish this carburetor from the Series 6 by the fixed idle jet that appears as a screw just above the bowl on the primer side.Series 8 Series 8 carburetors have both a fixed main and a fixed idle circuit.
check for spark by removing the high tension lead and removing the spark plug. excessive choking or over priming.TESTING 1. 2. BE SURE THE ENGINE IS COOL. remove the fuel line clamp on the carburetor fuel inlet and pull the fuel line off the fitting. Install a commercially available spark tester and check for spark. Replace the spark plug if questionable. See Chapter 9 under Troubleshooting. 8. With a proper draining receptacle. turn the engine over slowly 3 or 4 times to remove excess gasoline from the engine cylinder. Consult microfiche card #30 to find the correct R. 7. Start the engine and allow it to warm to operating temperature. improperly adjusted or defective carburetor. due to the fuels quality and short shelf life. heater box. See Service in this chapter or consult the Carburetion Troubleshooting chart to diagnose carburetor symptoms. Always check fuel as a primary cause of engine performance. 4. 6. With the spark plug removed and a shop towel over the spark plug hole. If no or irregular spark see Chapter 8 under "Testing". PLUG 3. See the proceeding Carburetion Troubleshooting chart for additional causes. Identify the correct carburetor model and manufacturer to find locations of the high and low speed adjustment screws. a dry spark plug. AVOID THE SPRAY FROM THE SPARK PLUG HOLE WHEN CRANKING THE ENGINE OVER. air filter replaced or clean). If the engine floods and fails to start. See Chapter 8 Ignition under Troubleshooting. CAUTION: KEEP ALL COMBUSTIVE SOURCES AWAY. 9. fresh fuel. Visually inspect the removed spark plug for a wet condition indicating the presence of gasoline in the cylinder. AND AWAY FROM ANY OPEN FLAME OR COMBUSTION SOURCE. 12 . If the spark plug is dry. proceed to step 2. CHECK THE FUEL CAP FOR PROPER VENTING. Check for the proper governor adjustments as outlined in Chapter 4. Check to see if the normal maintenance procedures have been performed (oil changed. adequate fuel flow. 17). Install the spark plug and high tension lead and try to start the engine. the carburetor will need to be removed for service. The carburetor can now be adjusted. After repeated efforts to start the engine using the procedure listed in the operators manual fail. and a known good functional carburetor indicates an internal engine problem exists. the carburetor will require service. SERVICE Carburetor Pre-sets and Adjustments Before adjusting any mixture screws the necessary carburetor presets should be made. If the fuel flow from the tank is adequate and no fuel is evident during priming. STANDARD OHV NOTE: Check plug for correct reach (diag. filter or tank require cleaning or replacement. If the carburetor is functioning properly the problem may be ignition timing related. Examine the fuel flow with the fuel cap both on and off the fuel tank. continue with step # 7. Low compression. check for restrictions in the fuel system before the carburetor. Check the engine compression using a commercially available compression tester and follow the testers recommended procedure. If the spark is bright blue and consistent.M. A wet spark plug indicates fuel is being supplied by the carburetor. settings for the engine. See Chapter 4 under "Speed Controls and Linkage". carbon shorted or defective spark plug. NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS. Replace the air filter if restricted or oil soaked. Check the throttle control bracket for proper adjustment allowing a full choke shutter position. fuel line. Remove the air filter. 5. Improper fuel flow indicates the fuel.P. or air cleaner assembly if applicable to visually check that the choke shutter completely closes or check to see if fuel comes out of the main nozzle during priming. 17 CAUTION: DRAIN THE FUEL INTO AN APPROVED CONTAINER OUTDOORS. If the spark plug is wet. NOTE: Todays fuels can cause many problems in an engines performance. The engine may be flooded by a restricted air filter.
IDENTIFY THE SERIES OF CARBURETOR USING THE VISUAL IDENTIFICATION IN THIS CHAPTER.M. Adjust the idle mixture screw following the same procedure used to adjust the main mixture adjustment screw. if fixed Final Adjustments Start the engine and allow it to warm up to normal operating temperature (3 . Set the speed control to the HIGH or FAST position.5 minutes). Note the position of the screw. Turn the screw in (clockwise) midway between these two positions.Pre-sets and Adjustments (Tecumseh and Walbro carburetors) Turn both the main and idle mixture adjusting screws in (clockwise) until finger tight if applicable.P. NOTE: OVERTIGHTENING WILL DAMAGE THE TAPERED PORTION OF THE NEEDLE. Now back the mixture screws out (counterclockwise) to obtain the pre-set figure in the chart shown. then turn the main mixture adjustment screw in (clockwise) slowly until the engine begins to run erratic. NOTE: SOME CARBURETORS HAVE FIXED IDLE AND MAIN JETS. Set the speed control to the IDLE or SLOW position. NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS. Now. IDLE MIXTURE FIXED JETS APPEAR AS ADJUSTING SCREWS WITHOUT TENSION SPRINGS AND ARE NOT ADJUSTABLE. then locate the recommended HIGH and LOW R. Tecumseh Carburetors Engine Model Main Pre-set Idle Pre-set 1 turn All models with float-type carburetors 1-1/2 turn All models with diaphragm-type carburetors Carburetor Model LMK 1 turn 1 turn Walbro Carburetors Fixed 1 turn if adjustable or seated. Identify the location of both HIGH and LOW speed adjustments. TECUMSEH CARBURETORS DUAL SYSTEM / SERIES "6" SERIES "7" SERIES "3" & "4" NON-ADJUSTABLE PRIMER NO CHOKE 18 FIXED HIGH AND LOW SPEED MIXTURE 19 IDLE MIXTURE SCREW MAIN MIXTURE SCREW WALBRO CARBURETOR SERIES "8" SERIES "9" SERIES "10" WALBRO LMK 20 CAPPED FIXED IDLE JET NON-ADJUSTABLE (ADJUSTABLE MAIN FOR EXPORT) 21 NON-ADJUSTABLE 22 23 24 13 . setting according to microfiche card # 30 and adjust the engine speed accordingly. This will be the best setting. turn the screw out (counterclockwise) until the engine begins to run erratic.
turn the idle mixture screw 1/8 turn either in (clockwise) or out (counterclockwise) until engine idles smoothly. Remove the float. Remove the throttle shutter. Remove the float hinge pin with a needlenose pliers. On Series 7 only. grasp the crossbrace on the float with a needlenose pliers and pull straight out to release the float hinge pin. setting and adjust as necessary. testing each setting with the equipment under load. grasp the choke shutter with a pliers and pull it through the slot in the choke shaft. release the wire retainer that retains the bowl and remove the bowl assembly. 1. 7. Remove the spring. clip. Remove the inlet needle seat using a wire or a paper clip with a 3/32" (2. Note the position of the spring clip on the inlet needle and float. The cap is removed by piercing it with an ice pick or similar instrument. Note or mark the high and low mixture adjusting screws to aid in reassembly (if applicable). and float bowl. the main adjustment should be made under a load condition. On Series 7 carburetors. Note the position of the hooks before removing the float hinge pin (diag. 4. CARBURETOR DISASSEMBLY PROCEDURE NOTE : CARBURETORS THAT ARE EMISSION COMPLIANT (MANUFACTURING NUMBERS 5000 OR GREATER) WITH FIXED IDLE OR MAIN JETS ARE TO BE REMOVED BY DEALERS ONLY FOR INSPECTION AND CLEANING.M. choke shutter. If a screwdriver or similar tool is used to release the retainer. 3/32" (2. Slide the choke shaft out of the carburetor body. If the engine stops or hesitates while engaging the load (lean). Remove the bowl drain screw and gasket.38 mm) hook end (Tecumseh carburetors only. 6. 5. always replace the cap. On Series 7 carburetors. springs and choke shaft by removing the screw or screws that attach the throttle or choke shutter to the shaft inside the air horn. over the fixed idle jet. Note or mark the action of the choke and throttle shutters and the hook points of the choke or throttle return spring or seal retainer springs located on the top of the choke or throttle shaft. (diag.If further adjustment is required. Recheck the high and low R. Series 8 carburetors have a tamper resistant cap. throttle shaft. 25). testing each setting with the equipment under load. then remove the jet for service. To remove the choke shaft assembly on Series 7 or Walbro LMK carburetors. THE SHUTTERS HAVE BEVELED EDGES AND MUST BE INSTALLED IN THE ORIGINAL POSITION. 21). turn the main adjusting screw in (clockwise) 1/8 turn at a time. Remove the high speed mixture screw. until this condition is corrected. metering jet. and inlet needle. Walbro model LMK uses a non-serviceable seat). until this condition is corrected. the adjustments are reversed out for lean in for richer. A few Tecumseh carburetors were built as air adjust idle system. carefully move the retainer to prevent bending of the wire. 3. move the speed control to the IDLE or SLOW position. Some carburetors use a float dampening spring to aid the inlet valve to maintain a steady position in rough service applications. NOTE: MARK THE EDGES OF THE THROTTLE AND CHOKE SHUTTERS PRIOR TO DISASSEMBLY. remove the main nozzle tube. and "O" ring. turn the main mixture adjusting screw out (counterclockwise) 1/8 turn at a time.38 mm) LONG END OF CLIP CLIP OPEN END OF CLIP THROTTLE END CHOKE END 25 26 27 14 . bowl nut. Push the hook through the hole in the center of the seat and pull out to remove it. and spring located in the center leg of the carburetor bowl. If the engine smokes excessively (rich). 2.P. "O" ring. After the main mixture screw is set. Remove the idle mixture screw assembly. If the engine does not idle smoothly. If you have one.
*Valve. Insert the high altitude jet in the same hole. Use a small chisel sharpened to a 1/8" (3. 7. 8. Pump 4 . The parts can only can be assembled one way without damage. Pump Cover 7 . Pump (2) 9 . After installation.*Filter. Secure the carburetor in a vise equipped with protective jaws. drive the jet through and into the center leg. Check (2) 6 . 28 10. Using a punch the same size or slightly smaller than the jet. tap it into place flush with the outside of the center leg casting (diag.175 mm) wide wedge point. Air 6 3 9 32 15 . The Walbro LMK carburetor main fuel jet can be removed only if the jet is damaged or if a high altitude jet is needed to be installed. 28).16 inch pounds (1. Spring 5 . 2.350 mm) flat washer and 1/2" (12. install the retaining screws. Remove the retainer by prying and lifting out with a screwdriver. The fitting must be replaced. thread the bolt into the shank. Clean the body parts with solvent.36 .Cover. If necessary the inlet fitting can be removed by pulling with a pliers or vise. Drive the chisel into the plug to pierce the metal and push down on the chisel to pry the plug out of the hole (diag. diaphragms. NOTE: DO NOT REMOVE ANY BALL OR CUP PLUGS (diag. 11. Pressure 11 .1.Bearing.700 mm) nut. To remove place the carburetor firmly in a soft jawed vice. Assemble the body sections.Body. and thread the nut down to pull out the shank. 29). 3. 9. Install the diaphragms against the center portion of the body with the gaskets against the outside covers. old valves and spring bearing from the spring. 9. Install new filter in pump cavity if applicable. and torque the screws to 12 . use 1/4"-20 bolt and nut inserted into a 1/4" (6. Note the direction of the inlet fitting.*Spring. Note or mark the pump body alignment. 1. Install new valves with the face of the valve facing the raised portion of the passage. SMALL CHISEL PRY OUT PLUG WALBRO LMK SERIES DO NOT REMOVE PLUGS ATMOSPHERIC PIERCE PLUG BRASS OR BALL PLUG VENT WITH TIP WELCH PLUG TO BE REMOVED DO NOT ALLOW CHISEL POINT ABOUT 1/8" TO STRIKE (3.81 Nm). 1-1/4" (4) 10 . 4. Remove all welch plugs if cleaning the carburetor.*Gasket.*Diaphragm. remove the four screws and disassemble the pump. 11 1 10 4 7 11 5 2 8 1 . Impluse 2 . Pump 3 . Install the spring bearing on the new spring and place into position. 31). Remove the old filter on the back of the pump body if applicable. Using a punch slightly larger than the diameter of the new jet. Do not reuse old bulb or retainer (diag. 6. Remove the primer bulb (if equipped) by grasping with a pliers and pulling and twisting out of the body. 29). 5. cut off the extended portion of the valves. Tap a 1/4-20 thread inside the metal shank. Remove the gaskets.8.Body. do not twist.175 mm) CARBURETOR WIDE BODY OR CHANNEL SMALL CHISEL REDUCER 29 BALL PLUG IDLE FUEL PASSAGE REDUCTION ROD INSIDE 30 HIGH SPEED JET 31 Impulse Fuel Pump The valve type impulse pump can be serviced using the following procedure.Screw.
36mm) diameter drill bit across the top of the carburetor casting on the opposite side and parallel to the float hinge pin. THE TECUMSEH SERIES 7 AND THE WALBRO MODEL LMK CARBURETOR HAVE A FIXED AND NONADJUSTABLE FLOAT HEIGHT. The tip and tapered surface of the needle must not show any wear or damage. 16 IDLE FUEL FUELTRANSFER INLET FUELPASSAGE METERING PORT ONE-HOLE TYPE TW0-HOLE TYPE 35 . float style carburetors may use either one or two metering ports. NOTE: DO NOT INTERCHANGE BOWL NUTS. Any excessive wear in these areas can cause dirt to enter the engine and cause premature wear. Remove the bowl nut. Throttle and Choke Examine the throttle and choke shaft. replace the needle. and "O" ring. Inspection After careful disassembly of the carburetor and the removal of all non metallic parts. and carburetor body at the bearing points and holes into which the linkage is fastened. Wearing eye protection. This passage must be clean for the proper transfer of fuel into the idle metering system. If a problem occurs with the idle system of the carburetor. hold the carburetor in an upside down position. this condition can be quickly corrected by loosening the carburetor bowl nut one full turn. and replace if worn or damaged. If either is worn or damaged. 35). Idle and High Speed Mixture Adjusting Screw Examine the idle mixture needle tip and tapered surface for damage. If dust seals are present. or commercial carburetor cleaner. depending on the application (diag. The fuel inlet ports must be free of any debris to allow proper fuel flow. The float must just touch the drill bit when the bit is flush with the edge of the float. This difference relates to calibration changes of the carburetor. then return the bowl to its original position and tighten the bowl nut. the tab adjustment may be made without removing the float and carefully inserting a small bladed screwdriver to bend the tab. 34). the welch plugs must be removed to expose the drilled passages. Replace the O ring seal if removed (diag. use compressed air and soft tag wire or monofilament fishing line to clean internal carburetor passages. FLOAT FLOAT HINGE AND AXLE FLOAT SETTING 11 / 64" (4. all metallic parts should be cleaned with solvent. replace the adjusting needle. To perform a proper carburetor rebuild. check the seal condition and the correct placement next to the carburetor body. If the tapered surface is damaged or shows wear. To check the float setting. Turn the bowl 1/4 inch in either direction. Bowl nuts that are used on adjustable main. If the required adjustment is minor. no longer than 30 minutes. If the float is too high or too low. Place an 11/64" (4. "O" RING BRASS WASHER SPRING HIGH SPEED ADJUSTMENT SCREW RETAINER NUT 34 Fuel Bowl Retaining Nut The bowl nut contains the passage through which fuel is delivered to the high speed and idle fuel system of the carburetor. Examine the tapered surface of the high speed mixture needle. Tension is maintained on the screw with a coil spring. adjust the height by bending the tab accordingly.36 mm) ADJUSTING TAB INLET NEEDLE AND SEAT 33 If float sticking occurs due to deposits. or when the fuel tank is filled for the first time.FLOAT ADJUSTING PROCEDURE All Tecumseh carburetors with an adjustable float require the correct float height to achieve the proper operation and easy engine starts. examine the small fuel passage in the annular groove in the bowl nut. float bowl.
9 & 10 38 CHOKE SHAFT THROTTLE SHAFT CHOKE DUST SEAL CHOKE RETURN SPRING CHOKE SHUTTER THROTTLE DUST SEAL THROTTLE RETURN SPRING IDLE SPEED SCREW WELCH PLUG IDLE MIXTURE SCREW TENSION SPRING THROTTLE SHUTTER FUEL FITTING INLET NEEDLE FLOAT FLOAT SHAFT SCREW PRIMER BULB FILTER ATMOSPHERIC VENT WELCH PLUG FLOAT "O" RING THROTTLE SHUTTER THROTTLE SHAFT & LEVER THROTTLE RETURN SPRING DUST SEAL WASHER DUST SEAL FUEL FITTING THROTTLE SHUTTER SCREW PRIMER BULB/ RETAINER RING "O" RING SEAT AND CLIP INLET NEEDLE SPRING CLIP FLOAT SHAFT FLOAT BOWL FLOAT BOWL BOWL NUT WASHER HIGH SPEED BOWL NUT BOWL NUT WASHER BOWL NUT WALBRO LMK 39 SERIES 6 40 17 . as well as the tab that contacts the inlet needle. FLOAT HINGE PIN NEEDLE & SEAT SEAT RETAINING RING FLOAT MAIN NOZZLE EMULSION "O" RING POSITIONED IN GROOVE SEAT NEEDLE SPRING CLIP HINGE PIN "O" RING NOZZLE "O" RING POSITIONED IN GROOVE SPRING IDLE RESTRICTION BOWL 'O' RING MAIN JET MAIN JET SPRING GASKET BOWL RETAINER SERIES 7 BOWL DRAIN BOWL WASHER JET/BOWL NUT 36 37 SERIES 8. Replace any damaged or worn parts. The needle and seat should be replaced if any fuel delivery problems are experienced (flooding or starvation). Check the float hinge bearing surfaces for wear. 37). Only the inlet needle is serviceable on the Walbro model LMK carburetor. Needle and Seat NOTE: To prevent damage to the float bowl on Series 7 carburetor. Examine the float for cracks or leaks. Sealing problems with the inlet needle seat may not be visible and replacement is recommended. Float.Fuel Bowl. pull straight up with a needle nose pliers in the pocket closest to the main fuel well (diag. Clean the bowl with solvent or carburetor cleaner (soak 30 minutes or less). The float bowl must be free of dirt and corrosion.
it is important that the lines. seal the outer diameter with fingernail polish (diag. Insert the throttle lever assembly into the carburetor body with both tangs of the return spring on the left side of the center boss (viewed from throttle end) and the flat side of the shaft toward the carburetor mounting flange. lettering. then tighten the throttle shutter screws. Test the operation of the throttle and return spring if equipped. Place the welch plug into the receptacle with the raised portion up. this line should be positioned in the 3 oclock position on Series 3. 9 carburetors. correct by loosening the screws and repositioning throttle plate. 41). or numbers on the throttle plate are facing out when in the closed position. After installation of the welch plug. install the throttle return spring on the throttle shaft with the squared end up. If necessary. Do not dent or drive the center of the plug below the top surface of the carburetor. Check for binding by rotating the throttle shaft. 44). merely flatten the plug. If binding occurs. 45). Slide the foam dust seal over the spring. New Tecumseh screws are treated with dry-type adhesive to secure them in place. then retighten the screws (diag. With a punch equal to the size of the plug hole. Apply light downward pressure on the throttle shaft and rotate it clockwise to seat the throttle shutter in the bore. 4. Always use a new screw(s) when reinstalling the throttle shutter to prevent the screws from loosening and being drawn into the engine. NOTE: NEVER REUSE OLD SCREWS. (diag. THROTTLE PLATE THROTTLE LEVER TWELVE O'CLOCK POSITION 42 THREE O'CLOCK POSITION 43 DUST SEALS SERIES 7 44 THROTTLE LEVER THROTTLE PLATE WALBRO LMK SERIES 45 18 . Install the screws so they are slightly loose. 42 & 43). 8. secure the carburetor in a vise equipped with protective jaws. Install the throttle shutter to the throttle shaft using notes or marks to place the shutter as originally found (Series 7 must have the line on the shutter at the 3 o'clock position) (diag. adjust the throttle shutter by loosening and repositioning the shutter. 6. FLAT END PUNCH NEW WELCH PLUG SAME OR LARGER DIAMETER OF PLUG HOLE 41 Throttle Shaft and Plate When reassembling Tecumseh or Walbro carburetors. If the throttle plate has only one line. On Walbro LMK and Series 7 carburetors.ASSEMBLY PROCEDURE Welch Plugs To install a new welch plug after cleaning the carburetor. Always use new throttle shutter screws when reinstalling. and 7 carburetors. and at the 12 o'clock position on Series 1.
CONSULT BULLETIN 110. On Series 7carburetors. Apply oil to the main nozzle "O" ring and push the main nozzle into the cavity with the "O" ring end in first. Test the operation of the choke and return spring function if equipped (diag. CHOKE PLATE FLAT DOWN 46 SPRING HOOKUPS Þ 47 PRESS IN PARTIALLY THEN APPLY LOCTITE SOME INLET FITTINGS STRAINER Fuel Inlet Fitting When installing the fitting. The choke shaft and plate must be in the closed position prior to tightening the screws. 48). Rotate the shaft and check for binding. Press it in until it bottoms out (diag. Place a new gasket on the drain screw and tighten in position (diag. Main Nozzle When reassembling. 47). On Walbro LMK carburetors. 49). Support the carburetor body with a wood block to avoid damage to other parts. install the choke return spring on the choke shaft with the squared end up and hooked into the notch in the plate. 46). insert the tip into the carburetor body. 49 FLOAT HINGE PIN FLOAT NEEDLE & SEAT SEAT RETAINING RING MAIN NOZZLE EMULSION "O" RING GROOVE POSITIONED IN SPRING IDLE RESTRICTION BOWL "O" RING MAIN JET MAIN JET SPRING GASKET BOWL DRAIN BOWL RETAINER 50 19 . Some carburetors may have a fixed main mixture or both a fixed idle mixture and main mixture. Note the cutout position of choke shutter if applicable. 50). NOTE: NEVER REUSE OLD SCREWS. Rotate the choke shaft approximately 1/4 turn counterclockwise and insert the choke shutter into the slot in the choke shaft. (diag. Correct by readjusting the choke plate to close completely. position the coil spring on the adjusting screws. On Walbro LMK and Series 7 carburetors. the main jet can be replaced by pressing it into the center leg of the carburetor until flush. Hard starting may be due to insufficient choking action because of a misaligned choke plate. Rotate the shaft counterclockwise until the tang on the spring rests against the left side of the center boss on the carburetor body (viewed from choke end) . Work the dust shield up around the spring and insert the choke shaft into the carburetor body. Use a bench vise or press to install the fitting squarely. Make sure it is assembled properly for the engine. followed by the small brass washer and the O ring seal. NOTE: FOR HIGH ALTITUDE JETTING. the choke must return to the open position when released (diag. 48 RETAINER NUT "O" RING BRASS WASHER SPRING HIGH SPEED ADJUSTMENT SCREW High and Low Speed Adjusting Screw. Next install the "O" ring in the main jet cavity. and are not adjustable. Always use a new screw(s) when reinstalling the choke shutter as the screws are treated with dry-type adhesive to secure them in place. Turn the high speed adjustment screw into the bowl nut and the low speed mixture screw into the carburetor body (diag. Choke plates will operate in either direction. Make sure the tabs on the shutter lock the choke shaft between them.Choke Shaft and Plate The choke plate is inserted into the air horn of the carburetor in such a position that the flat surface (if applicable) of the choke is down. 31 page 15). place the main nozzle spring into the main nozzle cavity. Place the spring over the shoulder on the main jet and push the jet into the cavity with the main jet toward the "O" ring.
LONG END OF CLIP Points toward choke end CLIP OPEN END OF CLIP THROTTLE END CHOKE END 52 Float Installation On Series 7 carburetors. install the seat retainer into the cavity and push it down using the flat punch until it contacts the seat.Inlet Needle and Seat Make sure the seat cavity is clean. To prevent binding. 2. This will ensure that the inlet needle will move up and down in a straight line (diag. Press the seat into the cavity using a 5/32" (3. LONG END OF CLIP Points toward choke end SERIES 7 WALBRO / LMK 53 CLIP OPEN END OF CLIP 54 POINTS TOWARD THE CHOKE END 55 20 . On Series 7 carburetors and the Walbro LMK. the long. Float height is not adjustable. Position the needle into the fuel inlet and snap the float pin into the tabs on the float bowl. PUSH IN UNTIL SEAT RESTS ON BODY SHOULDER IF YOUR CARBURETOR HAS A STEEL SEAT RETAINING RING RE-INTSALL AFTER SEAT INSTALLATION INLET NEEDLE SEATS AT THIS POINT 5/32" (3. Place the inlet needle and spring clip onto the float as shown. Some Tecumseh float style carburetors have a damper spring which is installed as shown in diag. 1. 4. straight end of the clip should face the choke or air filter end of the carburetor as shown (diag. 52). 53). When rebuilding a carburetor with a clip on the needle. To set the proper float height on carburetors except Series 7 and Walbro LMK. 53). The long end of the spring clip must point towards the choke end of the carburetor. see adjusting procedure. reinstall the inlet needle on to the float and place it into the carburetor (diag. Moisten the seat with oil and insert the seat with the grooved side down and away from the inlet needle. making sure it is firmly seated (diag. On Series "7" carburetors. 3. 55. slide the hinge pin into the hinge on the float. 51).969 mm) FLAT PUNCH SEAT INSERT THIS FACE FIRST 51 The inlet needle hooks onto the float tab by means of a spring clip. position carburetor float side up for assembly.969 mm) flat punch.
Final Checks Before reinstalling a newly overhauled carburetor. VALVE CLOSED ATMOSPHERIC VENT VALVE OPEN DIAPHRAGM FILTER AIR BLEED VALVE OPEN FUEL SUPPLY VALVE CLOSED PULSE LINE TO CRANKCASE FLOW DIRECTION á SUCTION FUEL PRESSURE ATMOSPHERIC ê CAUSED FUEL FLOW ê CRANKCASE PRESSURE á ATMOSPHERIC PRESSURE ACTING ON DAMPING DIAPHRAGM á FUEL FLOW ê CRANKCASE SUCTION AND FLOW DIRECTION á ATMOSPHERIC PRESSURE ACTING ON DAMPING DIAPHRAGM 57 Primer Bulb To install. Firmly push the bulb and retainer into position using a 3/4' (19. leaving the fuel line from the pump off. assemble the carburetor to the engine. lubricate the O ring with a small amount oil. The bowl has a small dimple located in the deepest part. a definite fuel flow should result at the pump outlet. the fuel bowl O ring (or gasket on Series "7") and the bowl nut washer must be replaced. 56 CARBURETOR FITTING Impulse Fuel Pump The diaphragms must be installed against the center body with the gaskets against the outside covers. See Pre-sets and Adjustments in this chapter. To test the unit.05 mm) deep well socket (diag. start the retainer and bulb into the casting with the retainer tabs pointed out. The parts are designed so they cannot be misassembled without damage (diag. the idle mixture adjustment screw and the idle speed adjustment screw. If the flow is erratic or intermittent. 58 21 . Place the pump outlet line in a proper draining receptacle. Make sure the deepest end of the bowl is opposite of the inlet needle.Fuel Bowl And Bowl Nut Whenever a carburetor bowl is removed for service. preset the main mixture adjustment screw. The purpose of this dimple is to minimize the chances of the float sticking to the bottom of the bowl caused by stale fuel. 57). Use a different fuel tank remotely placed above the carburetor to provide gravity fuel flow to the carburetor inlet to run the engine while testing the pump. Make sure fuel is available in both fuel tanks and the original fuel tank's fuel line is connected to the fuel pump inlet. With the pulse line connected from the engine crankcase to the pump and the engine running. 58). DETENT Installing the Float Bowl Install the float bowl by placing the detent portion opposite of the hinge pin. the pump needs repair or replacement. For easier installation.
Remove the governor gear assembly.M. cause the governor lever to move the solid link that is connected from the governor lever to the throttle in the carburetor. settings are critical. Check the governor spring for adequate tension or damaged condition. 5. OPERATION As the speed of an engine increases. If the engine R.see "Service" in this chapter. The governor rod maintains contact with the governor spool due to the governor spring tension.M. setting for high and low speed are within specification and a slight surge is experienced.M. Run the engine. does not stabilize.M. the engine will require disassembly to inspect the governor gear assembly for damage. The governor follower arm rests on the center of the governor spool on center force governors. check the engine R. 2. The governor rod rotates causing the attached outer governor lever to push the solid link and close the throttle opening. the governor weights on the governor gear move outward by centrifugal force.M. The governors function is to maintain a R. Try to stabilize the engine R. SPRING THROTTLE GOVERNOR SHAFT WEIGHTS GOVERNOR GEAR GOVERNOR SPOOL 1 TROUBLESHOOTING Engine operation problems where the governor is suspected to be the cause may actually be the result of other engine system failures. See "Service" governor adjustment procedure in this chapter. ENGINE SURGING 1. increasing the engine idle R. Check the condition of the external governor shaft. linkage. Engine overspeeding must be corrected immediately before serious engine damage occurs. If the R. 1). or improper hookup. 4.P. setting slightly may eliminate this condition. 6. 4. This chapter includes governor assembly linkage illustrations to aid in governor or speed control assembly.M. by holding in one position the solid link between the governor arm and the carburetor throttle. the governor or governor adjustment should be checked. Be ready to shut the engine off if an overspeed problem still exists. Follow the governor adjustment procedure and reset the governor .M. 2. If the problem persists after the governor adjustment. The throttle is opened when the engine R.P.P.M.CHAPTER 4 GOVERNORS AND LINKAGE GENERAL INFORMATION Tecumseh 4 cycle engines are equipped with mechanical type governors.M.P. If the problem persists. surging up and down) indicates that the engine is incapable of maintaining a constant R. Repair or replace as necessary. 3. If the engine R.M. and off to one side on other governor systems. When the engine speed decreases. drops and is closed as an engine load is removed.P. The R.P. Hunting (engine R.P. shut the engine off or slow it down immediately. The governor rod rotates and the solid link moves the throttle to a more open position (diag.P. the engine will require additional checks see Chapter 9 under "Troubleshooting".M. or wear. See Chapter 9 under "Disassembly Procedure" to disassemble the engine. the lower centrifugal force allows the governor weights to be pulled in by the governor spring. Check the governor shaft or linkages for binding. 3. Use the applicable following procedure to diagnose a suspected governor failure. governor spring. The shape of the governor weights force the governor spool to lift. and speed control assembly for breakage or binding. 22 . Mechanical type governors are driven off the engines camshaft gear.M. ENGINE OVERSPEEDING 1.P. If the engine runs wide open (faster than normal).P. using a pliers or fingers. Repair or replace as necessary. binding. with or without an engine load. Correct or replace binding or damaged parts. found on microfiche card # 30. stabilizes.P. wear.P. Changes in engine R. setting when engine loads are added or taken away.
loosen the screw holding the governor lever to the governor shaft clamp. Rotate the governor clamp counterclockwise on all overhead valve engines covered in this manual. Push the governor lever to move the carburetor throttle plate to the wide open position. To install a new shaft. 4).508 mm clearance) (diag. the retaining ring must be removed to allow the spool or gear to slide off the shaft. If the gear requires replacement. 4. Other governor shafts use an upset to hold the governor spool on. Grip the original spool in a vise and use a twisting and pulling motion on the flange until the spool is free.020" / . Ý GOVERNOR ROD GOVERNOR CLAMP SCREW YOU MUST USE THIS LINK POSITION ROTATE LEVER & ROD COUNTERCLOCKWISE THROTTLE OPEN (PUSH COUNTERGOVERNOR CLOCKWISE) LEVER GOVERNOR SCREW GOVERNOR ROD GOVERNOR CLAMP 2 OHH SERIES . the governor shaft will have to be removed. 2).010" . Start the shaft into the hole with a few taps from a soft faced hammer. GOVERNOR GEAR AND SHAFT SERVICE After the cylinder cover is removed from the engine. Hold the lever and clamp in this position while tightening the screw (diag. Upset Style Governor Shaft 1. first assemble the gear and washer on the shaft. On some governor assemblies. Press the shaft in until a part # 670297 (.3175 mm) shim just becomes snug (. PUSH LEVER TO WIDE OPEN THROTTLE GOVERNOR CLAMP SCREW THROTTLE LINK THROTTLE PLATE THROTTLE OPEN (PUSH COUNTERCLOCKWISE) STANDARD LOCATION GOVERNOR LEVER Ú TURN CLIP COUNTERCLOCKWISE ON ALL VERTICAL SHAFT ENGINES EXCEPT VLV & VLXL. OHSK 110. the governor spool.254-. Clamp the shaft in a vise and pound gently on the flange with a wooden or plastic mallet to remove the shaft (diag. 3. 5). 2. gear..120. Governor Gear or Shaft Replacement. CLOCKWISE ON ALL HORIZONTAL SHAFT ENGINES EXCEPT OHH.SERVICE GOVERNOR ADJUSTMENT With the engine stopped. or governor shaft can be removed.55 & OHM.OHSK 50.OLD STYLE 3 4 GEAR SHIM WASHER SHAFT BOSS 5 670297 (modified) 23 . NOTE: DO NOT TWIST THE SHAFT WHEN REMOVING. THE SHAFT BOSS MAY BECOME ENLARGED AND THE PRESS FIT WILL NOT SECURE THE NEW GOVERNOR SHAFT.0125" / . Place the flange in a press with a solid piece supporting the area below the shaft boss.NEW STYLE THROTTLE PLATE (TOP VIEW) ROTATE CLAMP COUNTERCLOCKWISE OHH SERIES .
Remove the retaining ring.33. Refer to the chart at right for the proper shaft exposed length from the mounting surface.559 .319" . and washer(s). (GOV. 2.100" (27. governor gear. (GOV.27. and spool followed by the retaining ring.365" (34. spool. THE SHAFT BOSS MAY BECOME ENLARGED AND THE PRESS FIT WILL NOT SECURE THE NEW GOVERNOR SHAFT. gear assembly. Reassemble the washer (s). 4.) SPACER WASHER SHAFT SHAFT OVRM TYPE I 7 OVRM TYPE II 8 MEDIUM FRAME 9 OHH / OHSK50-70 10 OVM / OHV / OHM OHSK80-130 11 24 . Start the new shaft into the shaft boss by tapping with a soft faced hammer.) WASHER GEAR ASSY.350" . 5. (GOV.) WASHER GEAR ASSY. 3. SPACER MAY BE PART OF THE GEAR ASSEMBLY. Wipe the extra Loctite off after installation.290-34. NOTE: DO NOT TWIST THE GOVERNOR SHAFT WHEN REMOVING.883 mm) 1.) WASHER SHAFT SPOOL WASHER RETAINING RING GEAR ASSY. Retaining Ring Style 1. (GOV.671 mm) 6 RETAINING RING SPOOL SERVICED AS ASSEMBLY RETAINING RING SPOOL UPSET SPOOL SPOOL WASHER RETAINING RING GEAR ASSY. Add a drop of red Loctite 271 and press the governor shaft to the proper depth using a press or a vise.Governor Shaft Replacement.502 .334" (33.1. (GOV.940 mm) 1. ENGINE MODEL OHH/OHSK50-70 OVRM OHM OHSK80-130 OVM OVXL OHV EXPOSED SHAFT LENGTH 1.1. Clamp the shaft in a vise and pound gently on the flange with a wooden or plastic mallet to remove the shaft.1.085" .) WASHER SPACER NOTE. SHAFT RETAINING RING SHAFT GEAR ASSY.
Speed Controls And Linkage Many different types of speed controls and linkage are used for O. 13 OHH GOVERNED IDLE SPEED CONTROL This control is adjusted by bending the tabs on the control bracket to achieve the correct idle speed and high speed.P. Loosen the two screws on the top of the panel. 14 & 16). tighten the two screws on the control panel. Use a Vibra-Tach or other tachometer and bend the tab as shown to achieve the specified governed idle speed. Use microfiche card #30 or contact a local Tecumseh dealer for the correct R. the governor controls both the idle and the high engine speed. In order for the governor to respond properly to a crankshaft load at engine idle. 2. settings for the engine model and specification.P. 4. adjustment screws may be located on the speed control bracket. use the following steps. With the components aligned. the hole in the choke actuating lever. Start and allow the engine to run ( 3-5 minutes) before beginning adjustments. the idle speed screw on the top of the carburetor must be set 600 RPM lower than the governed idle speed. 25 . and high speed R. Move the control lever to full wide open throttle position and install a wire or aligning pin through the hole in the top of the panel. Use a Vibra-Tach or other tachometer to set the non-governed idle speed (600 RPM lower than the governed idle speed) by pushing the bottom of the governor lever away from the control bracket so the throttle lever contacts the idle speed screw and hold the lever in this position. Place the control knob in the lowest engine speed position. The ignition ground out terminal. The adjustable speed control bracket which is mounted on the intake pipe must be aligned properly when installing. To align the control bracket. 3. The governor spring is connected between the speed control lever and the governor lever. move the engine control lever to contact the high speed stop. idle R. 3. This assures the correct placement during reassembly. Turn the idle speed screw clockwise to increase or counterclockwise to decrease engine idle speed. 1. 12 HIGH SPEED STOP OHH REMOTE SPEED CONTROL The engine and equipment control must be adjusted to allow the engine control lever to touch the high speed stop when the equipment control is set in the "highspeed" or "fast" position.M.M. The solid link is always connected from the outermost hole in the governor lever to the throttle in the carburetor.M. the engine R. Check to find the correct engine speeds found on microfiche card # 30 or using the Computer Parts Lookup System. Slide the control knob to the high speed position and bend the tab as shown to achieve the specified governed high engine speed. applications. When the engine is running. and hold the lever in this position while tightening the bowden wire clamp. Use the following procedure to set the engine speeds (diag. Linkage attachment points are best recorded or marked prior to disassembly. 2. or a vertical or horizontal control mounted on the side of the engine.M. Loosen the bowden wire clamp.P. NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS.'s should also be checked. Vertical shaft engines may use an adjustable intake pipe mounted speed control bracket located above the carburetor. place the equipment control to the "fast" position.E. 12). Whenever the carburetor or the governor linkage is removed or replaced. The following pages show common linkage hookup arrangements. and the hole in the choke (diag.P. 1. Allow the governor to control the throttle.M.
WINTER APPLICATION CONTROL GOVERNED IDLE LINK AND ADJUSTMENT HIGH SPEED ADJUSTMENT HIGH SPEED ADJUST BEND TO ADJUST SPEED DECREASE Þ INCREASE OHH REMOTE & MANUAL INCREASE GOVERNOR SPRING GOVERNED IDLE LINK CORRECT BUSHING INSTALLATION DEEP SIDE HERE GOVERNED IDLE TAB OHH RV CONTROL THROTTLE CRACK SCREW T-10 16 OH / OHSK CONTROL LOW SPEED TAB HIGH SPEED PIN POSITION HIGH SPEED TAB GOVERNED HIGH SPEED ADJUST GOVERNED IDLE SCREW OHSK / OHM CONTROL NOTE: ON REMOTE CONTROL THIS WILL NOT BE PRESENT HIGH SPEED ADJUST 18 OVRM SNAP IN CONTROL LOW SPEED ADJUST OVRM 26 20 OVRM Þ Þ Þ Þ 14 OHH FIXED SPEED THROTTLE CRACK SCREW T-10 15 GOVERNED HIGH SPEED ADJUST Þ BEND Þ DECREASE 17 DECREASE INCREASE Þ 19 21 . set only the idle crack screw and high speed governor stop.NOTE: Early production OHH engines did not have governed idle.
HIGH SPEED ADJUST GOVERNED IDLE ADJUST OVM / OVXL GOVERNOR OVERRIDE 22 OHV11 . Install the lock nut. Reassembly of REMOTE control.D.525 mm) locknut. thus allowing the engine to be stopped at either the stop in the control or the remote grounding switch. A remote grounding switch can be added to the engine at this terminal as well. Discard the detent bearing plate and in its place install the washer with the smaller I. then the bushing. Place the other washer with the large I. and the detent bearing plate. (2 Nm). from the new parts bag. Check the alignment of the lever. Discard the wave washer. The control lever should move freely.D. This engine speed control is set up with the "stop in the control". wave washer. Remove the 3/8" (9. 27 . bushing. control lever. lbs. The smaller side of the bushing goes towards the lever and fits inside of the lever and the washer. Install the lever over the post making sure that the end of the lever is in the slot of the control. Reinstall the blade and screw. If a remote stop is desired remove and discard the short green wire that runs from the speed control grounding terminal (to the remote grommet stop blade). from the parts bag next to lever.17 SPEED CONTROL 23 SPEED CONTROL BRACKET DETENT BEARING PLATE CONDUIT CLIP BUSHING LOCK NUT SCREW CONTROL KNOB GROUNDING TERMINAL WAVE WASHER ADDITION BOWDEN WIRE BRACKET CONTROL LEVER WASHER NOTE: THIS CONTROL IS STANDARD ON SERVICE ENGINES AND IS OPTIONAL TO CUSTOMERS 24 CONVERSION TO REMOTE CONTROL Remove the manual control knob by squeezing together with a pliers or prying with a screw driver. It will now be necessary to run a grounding wire to a remote grounding switch in order to stop the engine. Remove the air cleaner cover and air cleaner element to gain easier access to the speed control lock nut that holds the control levers together. bushing and washers to ensure that everything is aligned properly and torque the lock nut to 20 in.
778 mm) should exist at the gap location as illustrated.02 . hook the bowden cable end in the control as shown. NOTE: Assure that the throttle cable has full travel from wide open throttle to full choke.P. The idle speed is adjusted by turning the idle speed screw clockwise to increase engine R. Place a pin through the two holes.070" (1. This will assure that the carburetor will go into full choke when the control is placed in the start position. 12 on page 25).P. Make sure they are in good condition and in place (diag. place the equipment throttle control to the wide open position.040" . 28 TOOL #670326 Þ OVM. Place the slotted end of the tool onto the adjustment tab and bend the tab to the left (away from the control) to increase engine R. IDLE ADJUSTING SCREW HIGH SPEED ADJUSTMENT TAB THROTTLE LINK HOOKUP ALIGNMENT HOLE OHV 11-17 HORIZONTAL SPEED CONTROL This speed control is adjusted to the equipment throttle control by aligning the slot in the speed control lever with the alignment hole on the mounting bracket.This remote speed control may have governed idle. The speed control is adjusted to the equipment throttle control by aligning the slot in the speed control lever with the alignment hole on the mounting bracket. The idle speed is adjusted by turning the idle speed screw clockwise to increase engine R. OHV VERTICAL SPEED CONTROL DECREASE INCREASE Þ HIGH SPEED ADJUSTING LEVER BEND TO ADJUST HIGH SPEED . Hard starting could result if the cable is not properly adjusted to allow for full choke.P.040" .02 .1.M.P. the gap of ..M.1.P.778 mm) GAP LOCATION CHOKE ADJUSTING TAB CONTROL LEVER HIGH SPEED PIN POSITION OHV VERTICAL CONTROL 25 CHOKE HOOKUP IDLE SPEED SCREW CHOKE LEVER AIR GAP (.1. Use tool part # 670326 to adjust the high speed engine R..02 . and tighten the cable housing clamp.M.040 . In this position. OVXL. hook the bowden cable end in the control as shown.070" (1.070 (1. the gap of .1.M. 27).778 mm) should exist at the gap location as illustrated. and counterclockwise to decrease R. In this position. Place a pin through the two holes.M.P. This adjusts choke in control as well (diag. and tighten the cable housing clamp.M.. a choke override.P.02 .778 mm) BEND TAB TO ADJUST OHV 11 .. This will assure that the carburetor will go into full choke when the control is placed in the start position.17 HORIZONTAL CONTROL 26 LINKAGE BUSHING 27 . and the option of an ignition remote stop terminal block. Use tool part # 670326 to adjust the high speed engine R. Throttle plate alignment on all models with speed controls mounted on intake manifold.P. place the equipment throttle control to the wide open position.M.M. Place the slotted end of the tool onto the adjustment tab and bend the tab to the left (toward the spark plug end) to increase engine R.070") (1.040 . OHV 11 -17 engines use nylon bushings on the throttle and choke linkage hook-up points to extend the life of the linkage and to enhance the stability of the governor system. and counterclockwise to decrease R.
Consult the Tecumseh Master Parts Manual to obtain the correct part number. washers. The retainer ears act as a ramp to fully extend the starter dog(s). ROPE SERVICE Rope replacement should be done using the correct part number replacement rope or braided rope of the correct diameter and length. the starter pulley rotates on the center pin. The rope ends should be cauterized by burning with a match and wiping the rope end with a cloth while hot. Use one of the following procedures that apply to the application to disassemble. COMPONENTS ROPE HANDLE STARTER HOUSING HANDLE HOUSING PULLEY AND REWIND SPRING ASSY.CHAPTER 5 RECOIL STARTERS GENERAL INFORMATION Recoil starters used on vertical shaft Tecumseh engines are top mount horizontal pull style. the recoil spring turns the starter pulley in the opposite direction to retract the starter rope. rope. the starter dog(s) disengages from the starter cup. STARTER DOG DOG SPRING WASHER RETAINER BRAKE SPRING WASHER SPRING PIN DOG SPRING RETAINER BRAKE SPRING SPRING & KEEPER PULLEY 1 DOG BRAKE WASHER CAM DOG CENTER 2 SCREW SERVICE Starter related problems will require the starter to be removed from the engine to diagnose the cause. Use the following rope chart to convert a numbered rope to a fractional diameter for bulk rope use. When the engine fires and the rotational speed of the starter cup exceeds the starter pulley. and size required. Horizontal shaft engines use recoil starters which can be mounted to pull either vertically or horizontally. 29 . All starters are spring loaded to retract the dog(s) when the engine speed exceeds the turning speed of the starter. starter cup. When the starter handle is released. All recoil starters turn the engine over by engaging a dog(s) into the starter cup attached to the engine flywheel. OPERATION As the starter rope is pulled. retainer. The starter dog spring(s) returns the starter dog(s) to the disengaged position. repair. The fully extended starter dog(s) locks in contact with notches in the starter cup. length. Visually inspect the starter dog(s). and the starter pulley for wear or breakage. The starter dog(s) is pinned or pocketed in the pulley hub and extend outward when the pulley rotation forces the starter dog(s) to contact the ears on the retainer. Always consult the Tecumseh Master Parts Manual for the correct replacement parts. springs. and assemble the starter.
969 mm) 3/16" diameter (4. Slide the rope retainer into the proper position and insert the staple using a pliers. Install the starter handle and tie a left hand knot to secure the handle. OVXL.35 mm) punch for stamped steel] roll pin punch to drive out the center pin. The stamped steel center pin is driven out from the outside.4 mm) deep well socket under the retainer. Note: The starter dogs face out on the stamped steel starter and the dogs face in on the stylized rewind starter. STARTER DOG DOG SPRING WASHER RETAINER LEFT-HAND KNOT BRAKE SPRING WASHER SPRING PIN 4 5 30 . OHSK. AND EXTINGUISH COMPLETELY BEFORE DISCARDING. PULLEY BOSSES HOLD THE REWIND SPRING AND COVER. 4). retainer.762mm) ROPE RETAINER REPLACEMENT 1. 4). # 4 1/2 rope = # 5 rope # 6 rope = = 9/64" diameter (3. OVRM. ONE PIECE ROPE RETAINER STAPLE 3 STYLIZED REWIND STARTER (OHH. OHM.572 mm) 5/32" diameter (3. Move the punch around while driving the pin to help keep the pin straight. AND CAN BE EASILY DISLODGED DURING HANDLING. 2. Remove the brake spring. Remove the staple and old retainer. washers. HANDLE ROPE STARTER HOUSING PULLEY AND REWIND SPRING ASSY. 5.CAUTION: HANDLE MATCHES SAFELY TO AVOID BURNS. After removing the rewind assembly from the engine blower housing. the punch tip must be angled inside the center hole. CAUTION: THIS REWIND SPRING IS NOT SECURED IN A CANISTER. OHV). 3. Place a 1" (25. and pulley assembly (diag. 3. supported on the socket. and STAMPED STEEL STARTER Disassembly Procedure 1.937 mm) or a [1/4" (6. Remove the starter handle if the retainer is a complete circle design. 2. release the tension on the rewind spring. 6. 4. Remove the starter handle and carefully allow the rope to unwind into the starter housing (diag. Remove the decal or plastic disc in the center of the rewind. OVM. Set the rewind on a bench. Use a 5/16" (7. All components in need of service should be replaced.
and either untying the knot in handle or prying out the staple. DOG SPRING WASHER RETAINER STARTER DOG BRAKE SPRING WASHER SPRING PIN 6 STARTER HOUSING HANDLE ROPE PULLEY AND REWIND SPRING ASSY. Untie the temporary knot and slowly allow the rope to fully retract into the starter housing and the recoil spring to fully unwind. After removing the rewind assembly from the engine blower housing. Pull enough rope through to tie a temporary knot in the rope. DOG SPRING STARTER DOG WASHER RETAINER LEFT-HAND KNOT BRAKE SPRING WASHER SPRING PIN 7 STYLIZED REWIND STARTER WITH PLASTIC RETAINER Disassembly Procedure 1. 4.175 mm) of the top of the starter. 5. Replacing rope wind the starter pulley counterclockwise four or five turns to pre-load the recoil spring and thread the rope through the starter housing eyelet. Reverse the disassembly procedure. New plastic washers are provided with a new center spring pin. Install a new recoil spring if necessary by pushing the new spring out of the holder into the pulley cavity while aligning the outside spring hook into the deep notch in the pulley. Remove the decal from the center of the starter housing. 3. remove the starter handle by first pulling a length of rope out using the handle. Untie the temporary knot and allow the rope to recoil. Reattach the starter handle to the rope using a left-hand knot. (diag. STARTER HOUSING HANDLE HANDLE INSERT ROPE PULLEY AND REWIND SPRING ASSY. tying a temporary knot in the exposed rope. The starter dogs with the dog springs must snap back to the center of the pulley (disengaged position). NOTE: DO NOT DRIVE THE CENTER PIN IN TOO FAR. Push the spring cover in until seated. On the stamped steel starter the center pin should be driven in until it contacts the shoulder in the starter housing. Always replace the center spring pin with a new one upon reassembly. the tabs on the retainer must be positioned so that they will force the starter dogs to engage the starter cup. Place the two new plastic washers between the center leg of the starter and the retainer. 3. Discard the old plastic washer. The retainer will bend and the starter dogs will not engage the starter cup. Place the rewind on a flat surface and drive the new center pin in until it is within 1/8" (3.Assembly Procedure 1. 6 & 7) 2. When the rope is pulled. RETAINER WEDGE STARTER HOUSING STARTER PULLEY SPRING & COVER DOG SPRING STARTER DOG DOG RETAINER 8 31 . 2.
Untie the knot in the rope and slowly release the spring tension. Replace or check that both starter dogs are in the pulley pockets and that the dog springs are hooked on the outer surface of the dog.NEW STYLE) STARTER HOUSING Assembly 1. 4. Pinch the legs of the retainer together and pull on the head of the retainer to remove it from the housing. 6. Use a small Phillips screwdriver or similar tool to pry the retainer legs apart and lift out the retaining wedge. 2. Wind the starter pulley counterclockwise four or five turns to pre-load the recoil spring and thread the rope through the starter housing eyelet. 7. 10). Push the spring cover in until seated. 6. Lift the pulley out of the starter housing. Remove the pulley assembly from the recoil housing. Turn the starter over and snap the locking tab between the retainer legs. Push the retainer in until the leg prongs pop out of the center shaft. Rotate the retainer so the two tabs on the bottom of the part fit between the dog and pulley hub (left side of the dog). replace the top decal. Reattach the starter handle to the rope using a left-hand knot.4. and brake spring (diag. 2. 5. see Step 8. starter dog(s) and dog spring(s). Pinch the two legs of the plastic retainer together and start into the center shaft hole. Repair or replace as necessary. NOTE: Refer to Service Bulletin 122 for metal locking tab. retainer (cam dog on snow proof type). 32 HANDLE HANDLE INSERT PULLEY LEFT-HAND KNOT CAM DOG WASHER DOG SPRING STARTER DOG DOG RETAINER RETAINER SCREW BRAKE SPRING SPRING PIN "STAMPED STEEL WITH ROLL PIN" 10 . 8. 5. ROPE KEEPER SPRING STYLE STARTERS Disassembly Procedure 1. Remove the center screw. Replace all worn or damaged parts. Apply a small amount of lithium grease to the inner bore of the center shaft. RETAINING WEDGE (STEEL CLIP . 3. 7. 3. If replacing the starter rope. Pull enough rope through to tie a temporary knot in the rope. Turn the spring and keeper assembly to remove the pulley. STARTER PULLEY SPRING & COVER DOG SPRING STARTER DOG DOG RETAINER 9 STARTER HOUSING REWIND SPRING AND KEEPER ASSY. Untie the temporary knot and allow the rope to recoil. Install a new recoil spring if necessary by pushing the new spring out of the holder into the pulley cavity while aligning the outside spring hook into the deep notch in the pulley.
11). Place the rewind spring and keeper assembly into the pulley. then allow the pulley to unwind until the hole in the pulley lines up with the rope eyelet in the starter housing. Install a knotted rope through the pulley and the eyelet and install the handle. 5.159 mm) drill bit. (7-8. 1. Follow illustration of your starter type as shown. Turn the pulley to lock into position.32 retainer screw can be replaced with a larger 12 . PULLEY BRAKE SPRING RETAINER DOG SPRNG RETAINER SCREW "STAMPED STEEL" CENTER PIN 11 STARTER HOUSING REWIND SPRING AND KEEPER ASSY. and starter dog return spring(s). Replace the retainer cup (cam dog on snow proof starter) and retainer screw. Install the brake spring. Re-drill the screw hole using a 13/64" (5. The center screw torque on cast aluminum starters is 115 to 135 in.28 screw (part # 590409A). lbs. Tension the recoil spring by winding the pulley counterclockwise until it becomes tight. 2. A left-hand knot should be tied on the end of the rope to secure the handle. lbs. A light coating of grease should be on the spring. 3. starter dog(s).5 Nm) Older models that use a 10 . Place the pulley assembly into the starter housing.Assembly Procedure HOUSING NOTE: This procedure covers three starters. ROPE HANDLE HANDLE INSERT PULLEY LEFT-HAND KNOT CAM DOG WASHER DOG SPRING STARTER DOG DOG RETAINER RETAINER SCREW BRAKE SPRING SPRING PIN "STAMPED STEEL WITH ROLL PIN" 12 HANDLE HOUSING SPRING & KEEPER PULLEY DOG SPRING RETAINER BRAKE SPRING "ALUMINUM HOUSING" DOG BRAKE WASHER CAM DOG CENTER SCREW 13 33 . 4. The starter dog spring(s) must hold the dog(s) in against the pulley.75 in. Tighten to 65 . (13-15 Nm) (diag. HANDLE SPRING & KEEPER ASSY.
tying a temporary knot in the exposed rope. starter dog spring.5 Nm) torque. 6. Remove the starter pulley. NOTE: Type II . Remove the starter dog retainer. 5. HOUSING BOSSES HOLD THE REWIND SPRING. Place the starter dog retainer on the center leg. 2. hook the end of the dog spring into the hole in the retainer. and hex nut. Remove the temporary knot and allow the rope to retract. metal washer. and place a temporary knot in the rope leaving at least one foot of rope length. place the brake spring and starter dog spring on the pulley. 6. 4. Wind the pulley counterclockwise 4-5 turns. 2. Slowly unwind the dog spring by allowing the starter dog retainer to rotate. 5. The starter dogs must be free to retract into the pulley pocket. and starter dogs. brake spring. Tighten the hex nut to 40 inch pounds (4. 34 STARTER DOG BRAKE SPRING LOCKWASHER STARTER DOG RETAINER CENTER SCREW STARTER HOUSING SPRING AND KEEPER PULLEY STARTER DOG RETAINER SPRING WASHER TYPE II 15 . 3.5 -17) 1. LEFT-HAND KNOT STARTER HOUSING REWIND SPRING PULLEY BRAKE SPRING STARTER DOGS STARTER DOG SPRING STARTER DOG RETAINER WASHER LOCKWASHER 6mm METRIC NUT TYPE I 14 Assembly 1. Remove the nut (using a 10 mm socket) and washers from the center leg of the recoil housing. Slide the starter handle on the end of the rope and secure using a left hand knot. lock washer. Pull the knot into the squared area and wind the rope counterclockwise (viewed from the pulley bottom) on the starter pulley. 3. press down and turn 1/2 a turn clockwise to line up the notches to the starter dogs.Stylized Starter (OHV 13. align the end of recoil spring and the notch in the pulley and push down until seated. Remove the starter handle by first pulling a length of rope out using the handle. Untie the temporary knot and slowly allow the rope to fully retract into the starter housing and the recoil spring to fully unwind. thread the rope through the starter housing hole. AND THE SPRING CAN BE EASILY DISLODGED DURING HANDLING.Apply blue Loctite to the center screw and torque to 70 in pounds (8 Nm). Remove the starter rope from the pulley if necessary. Replace the starter rope if removed by inserting one end through the hole in the side of the pulley and tying a left hand knot near the rope end. Insert the starter dogs on the pulley pegs with the flat side away from the pulley. Place the pulley on the housing center leg. 4. and untying the knot in the handle. CAUTION: THE REWIND SPRING IS NOT SECURED IN PLACE. add the nylon washer.
safety switches. ROTATION OF FLYWHEEL 2 35 . The power source used to provide the energy to turn an electric starter motor on Tecumseh engines is either 120 volt A. After the switch is released. battery cables.C. If a battery has a shorted cell. 1). the starting circuit is opened and the armature coasts to a stop. The greater momentum of the flywheel throws the starter pinion gear out of mesh and forces the starter pinion back to the disengaged position. and the regulator or rectifier may appear to be at fault. current or 12 volt D. the pinion rotates along with the armature shaft to crank the engine. LOCK NUT BOLT BRUSHES BRUSH SPRINGS BRUSH CARD HOUSING END CAP WASHER NUTS ARMATURE SPRING RETAINER RETAINER GEAR SPRING DUST COVER THRUST WASHER END CAP ENGAGING NUT 1 CHARGING CIRCUIT The charging system works independently of any manual controls. and an electric starter motor.C. and a battery. When a conductor (alternating coils) cuts the magnetic field generated by the magnets in the flywheel. The permanent magnets in the flywheel have a magnetic field in which the lines of magnetic force run from the North Pole to the South Pole. The charging system consists of alternator charge coils. a current is induced in the alternator coil. OPERATION STARTING CIRCUIT AND ELECTRIC STARTERS After all of the safety interlock switches have been activated. and a charging circuit. the electric starter operation will be affected. starter solenoid. flywheel magnets. The engine needs to be running to produce an electric current flow. If a cell has an open or high resistance connection.CHAPTER 6 ELECTRICAL SYSTEMS GENERAL INFORMATION The electrical system consists of three main elements: a battery. A small anti-drift spring holds the pinion in the disengaged position (diag. The armature magnetism repels the magnetism produced by the permanent field magnets of the electric starter. starter circuit utilizes a 120 volt power source instead of a battery. The alternating coils are wound in different directions to allow current to flow as an A. ignition switch.C. The starting circuit includes the battery. As the flywheel rotates and the position of the magnets change. regulator. When the drive pinion contacts the stop at the end of the armature shaft.C. The armature and pinion remain positively engaged until the engine fires and the flywheel rotates faster than the armature. meshing the starter pinion gear with the flywheel ring gear. 2). All engines that have a charging system will use a combination of some or all of these features. a starting circuit. waveform (diag. The repelling magnetic forces cause the armature to rotate. A 120 volt A. the direction of the magnetic field changes or alternates. starter or ignition switch. A strong magnetic force is produced by the electrical current running through the armature windings. The battery is part of both the starting and charging circuit. overcharging can result. The battery should be checked before going into any extensive starter or charging system checks. rectifiers or diodes. moving the drive pinion laterally on the splined armature shaft. The 12 volt battery models require a charging system to maintain proper battery charge. the starter switch closes the starting circuit.
) to direct current (D. OUTPUT 4 Full Wave Rectifier Bridge Rectifier The full wave rectifier makes use of the entire A.C.) + VOLTAGE D.C. To accomplish this. The chemical energy produced by the dissimilar metals of the battery plates provides a electrical potential that is used to power the electric starter or unit accessories. signal and is known as HALF WAVE RECTIFICATION (diag.C.C.VOLTAGE D.VOLTAGE A. This is of special concern when moisture or water is present.C. signal. signal.C. 4). Consult the original equipment manufacturers service manual for battery size. 5).C. This is accomplished by using a diode or rectifier (diag.VOLTAGE 5 WIRING The wires used in Tecumseh electrical systems are copper stranded with an insulated coating around the copper strands. signal through. + VOLTAGE FULL WAVE RECTIFIER (BRIDGE RECTIFIER) COMPONENTS BATTERY The batteries used in conjunction with Tecumseh engines are 12 volt lead acid or maintenance free style. multiple diodes in a bridge configuration are used to produce FULL WAVE RECTIFICATION (diag.C. + VOLTAGE HALF WAVE RECTIFIER (SINGLE DIODE) + VOLTAGE A. Remember to check the insulation on the wire. It does not allow the negative portion through. This is especially important in the use of batteries where much of the potential may be lost due to loose connections or corrosion. The cathode end of the diode should point toward the battery when diode is used between a charging system and a battery.C. 36 .C.C. and testing procedure. INPUT .VOLTAGE . 3). . This is acceptable in certain applications. In certain situations it is necessary to make use of the entire A. capacities. INPUT + VOLTAGE (D. it is necessary to convert alternating current (A.CONVERTING ALTERNATING CURRENT TO DIRECT CURRENT In order to charge a battery.C. A single diode makes use of only one half of the A.).C. ANODE CATHODE BAND OR OTHER MARKING INDICATES CATHODE END 3 Current flows through a diode when the anode is more positive than the cathode. Half Wave Rectifier Single Diode The single diode allows only the positive half of the A. securely fastened and free of foreign material (such as rust and corrosion) at the connection points. OUTPUT . CONDITION: All wiring must be fully insulated between connection points. converting it to D. INPUT A. All it takes is a pin hole for leakage to "ground out" on the engine or frame.
4. Battery Ground Leads 12 Volt Starter B + Leads Ignition Shut-Off Leads Dark Green - NOTE: PRIOR TO AUGUST 1992. Leads Alternator D. The magneto circuit wiring (ground circuit) must be rated at #18 or lower gauge number. the greater the number of coils. plastic.WIRE GAUGE: The proper thickness of wire is necessary in all electrical circuits. the greater the output of the alternator. When a magnet is moved past the coils. Defective switch. 3. but some are better conductors than others.C. be sure to perform the more basic checks first. THIS IS AN AREA THAT SHOULD BE CHECKED OUT. 1. THE LARGER THE NUMBER THE SMALLER THE WIRE # 18 #6 6 Tecumseh Products Company's standard wiring color codes effective August. 2. Wire diameter is measured in increments of gauge numbers. 5.* *NOTE: ALL LAWN AND GARDEN TRACTORS BUILT AFTER JULY OF 1987 ARE REQUIRED TO HAVE AN OPERATOR PRESENCE SYSTEM AND MANY CAME EQUIPPED WITH SUCH A SYSTEM PRIOR TO THIS DATE. 2.An alternator consists of coils of wire wound around a metal lamination stack. Operator presence system functioning properly. Battery defective or not charged. The charging circuit wiring must be rated at #16 or lower gauge number (20 amp system requires #14 or lower gauge number). rubber. WIRE CODES CHANGED ACCORDING TO MODEL AND SPECIFICATION NUMBERS. 1992 are as follows: Code Yellow Red Brown Black Orange Product Alternator A. The regulator prevents overcharging of the battery and the rectifier changes the alternating current to direct current.C. REGULATOR/RECTIFIERS .Charging a battery requires that the alternating current produced by the alternator be changed to direct current. . copper and gold are some of the better known conductors. This is accomplished by using a diode or rectifier.Leads Alternator Ground Leads. Corroded or loose terminals or connections. 6). IF THE TRACTOR IS "CUTTING OUT" OR WILL NOT START. 37 . or wrong connections.A conductor is a material that allows an electric current to pass through it. ELECTRICAL TERMS ALTERNATOR . 6. Cracked insulation or broken wires. In general. Some of the more common materials that are insulators are glass. + Leads Alternator D. BASIC CHECKS Before going into extensive checks. CONDUCTORS . such as: 1.An insulator is a material that will not allow an electric current to pass through it. RECTIFIERS and DIODES . the wire diameter decreases in size (diag. A wire "grounding out" in the system. 3. As the gauge number of the wire increases. a current is induced in the coils. INSULATORS . Silver.C. The starter circuit wiring must be rated at #6 or lower gauge number. ceramics and porcelain. All metals are conductors of electricity.This combines a regulator with a rectifier.
does engine turn over? YES Check starter for binding brushes. does engine YES turn over freely? Repair or replace equipment causing excessive loading Internal engine failure or flywheel interference NO Reinstall spark plug.TROUBLESHOOTING ELECTRICAL STARTER CIRCUIT FLOW CHART Starter will not turn Intermittent starter operation Starter turns at low rpms or stalls under load NO Is there power at the power source? YES Repair or replace power source NO Is power supplied to the starter terminal? YES Check wiring. Adjust if necessary. Does the engine turn over without binding now ? Internal engine failure repair or replace engine Internal engine failure repair or replace engine 38 . dirty or oily commutator NO Remove spark plug. worn brushes. connections. does engine bind on compression stroke? YES Repair or replace electric starter NO Check valve lash. safety switches. starter switch NO Isolate engine from the equipment.
TROUBLESHOOTING ELECTRICAL CHARGING CIRCUIT FLOW CHART Identify the charging system used by model and specification number or visually checking the electrical plug Consult the Mechanic's Handbook or Electrical Troubleshooting booklet for test procedure for the charging system used Test for either AC or DC voltage as directed at the proper engine RPM NO Is the voltage greater than or equal to the minimum value? YES NO Is AC voltage before diode or YES rectifier greater than the minimum value? Check wiring. or lights for shorts 39 . switches. replace if no continuity exists or if continuity exists reversing test leads Check fuses. Check diodes. replace as necessary Check switches. wiring. or ammeter for breaks. replace coil assy. shorts Alternator coil failure.
chains. To make many of the tests it is necessary to run the engine and measure alternator output with a voltmeter. the problem is an internal failure. Check for proper lubrication (oil level and viscosity) and check for electric starter gear and flywheel ring gear interference. starters labeled CSA must only be replaced.20 D. See Chapter 9 under "Disassembly Procedure". With the engine running. If there is no change in the voltage reading. See "Service" in this chapter. however. it is not necessary to take readings at all the listed R.s. 2. The charging system used on the engine is best identified by obtaining the engine model number and the specification number on the engine. and couplers to isolate the engine from the equipment it is powering. When making voltage tests with the engine running. If the preceding steps fail to correct the problem. If no problem is discovered. ELECTRIC SHOCK CAN KILL. volt scale. a mechanical binding may be the cause. Consult a Tecumseh dealer or a parts manual to identify the charging system. the alternator is defective and should be replaced. Make sure the battery meets the minimum battery voltage requirements found in the original equipment manufacturer's service manual. In some cases an open circuit D.C. output from the regulator / rectifier. (+) POSITIVE LEAD 350 Milliamp Charging System CHECKING THE SYSTEM: The battery must be in the circuit to perform the test properly. Set the voltmeter to the 0 . Remove all equipment loads from the engine. or 120v A. 6. Valve clearance not within the listed specifications will require resetting the rocker arms to obtain the proper clearance. VOLTAGE.M. there should be an increase in the voltage reading. The voltmeter should read the battery voltage. 4. Take off all drive belts. the engine will require to be disassembled to find the mechanical failure. Start the engine. 7).C. 7. the electric starter should be replaced or disassembled and checked. Check the electric starter terminal for the required voltage (12v D. or solenoid for continuity using a ohmmeter or a continuity light. CHARGING CIRCUIT The following pages will show wiring diagrams of several Tecumseh charging systems. ignition or starter switch.C. Connect a voltmeter across the battery.) using a voltmeter. OUTPUT LEAD (RED) ELECTRIC STARTER LEAD (ORG) 7 .C. the camshaft (compression release failure) may require replacement. If the engine turns over freely. Check the power source using an electrical tester and following the tester's recommended procedure.TESTING PROCEDURE STARTING CIRCUIT 1. Without the battery in the circuit this turn on voltage is not present. connections. Checking at one of the speeds is sufficient. The SCR senses this and there will be no D.C. Check wiring. check the engine valve clearance per the specification table in Chapter 10. check cannot be made. 5. Repair or replace as necessary. CAUTION: FOLLOW ALL SAFETY PRECAUTIONS WHEN TESTING FOR A. 120 volt starters labeled UL Listed/CSA Approved can be serviced. If the valve clearance is within the specifications. Try to turn the engine over using the recoil assembly if equipped. safety switches. 40 (-) ENGINE GROUND MAGNETO GROUND (GR) BATTERY GROUND (BL) BLACK RED D.P.C. A SCR (Silicon Controlled Rectifier) is located in the circuit which requires a minimum turn on voltage to allow it to conduct.C. If the engine doesnt turn over. If the engine binds only on the compression stroke. Each charging system has its own testing procedure. 3. See Chapter 9 for "Disassembly Procedure" (diag. Test the charging system using the applicable procedure found on the following pages. fuses.
M. D.C.C. 3600 R. .C.C. the alternator is okay.M. is good check each diode it services as requested see parts list.M. .9.C. R. NEGATIVE OUTPUT LEAD (BROWN D.C.0 Volts D. 26 Volts A.C. D. See Chapter 9 for "Disassembly Procedure". D.C.P.C. TWO DIODES RED D. 3600 . positive first. the alternator is defective. Start the engine and test the circuit using the A.P. #4414 BULB ENGINE YELLOW 8 3 AMP Before making any exterior tests. minimum values should read: 2500 R.5 Volts D.11.5 Volts D. 3300 .C. voltmeter as shown (diag. wiring or switches.C.0 Volts A.P.5 Volts A.P. 3300 R.C.5 Volts A.5 Volts A.0 Volts A.C.10. . check the A. lead to ground at each yellow wire (diag. A.8. 9). Volts 2500 .10.C. OUTPUT LEADS ARE BLACK AND RED. neg and D.11. the alternator is defective. Connect another wire lead to the other terminal of the bulb and run to a good ground on the engine.C. minimum A. 8). output.5 Volts A.M.C. NOTE: ON OLDER POINT IGNITION SYSTEMS. . 3000 R. POSITIVE OUTPUT LEAD (RED D. if less than the above readings. YELLOW GREEN IGNITION STOP YELLOW YELLOW 9 2. To check out the alternator.C. checking the D.M.C. .M. valve (+) or (-) check A. With the engine running.M.C.P. Lighting Alternator CHECKING THE SYSTEM: To check the system. Check for defective lights.0 Volts A.C.5 Volts D.C. the alternator is okay.P. With engine running.C. Connect a wire lead from the single pin connector coming out of the engine to one terminal of a No.C. 2500 3000 3600 Volts A. NOTE: These minimum numbers should be obtained by your meter and will often be higher.C.C. 10 41 . outputs both sides.M. If output is below standard listed pull back protective coating in front of the diode and check A. R.18 Watt A.M..C. 22 Volts A. 35 Watt Lighting To check this system follow the meter hook ups at the right.6. 3000 .P.C. disconnect the plug from the rest of the lighting system.C. 18 watt bulb. 4414. If less than the minimum values.9. . If minimum values are noted.C. check for inoperative switch. If A.) A.C.) D.C. 3600 R. voltage across the bulb should be: 2000 R.C.C. It the above minimum readings are noted.5 Amp D. 3000 R.C. 18 Volts A.P. shorted wires and burned out headlight and/ or stop tail light. . THE A.10.C.C.8.8. D. See Chapter 9 for "Disassembly Procedure".P.
11).M. 12). Þ 12 13 . BE CAREFUL NOT TO APPLY HEAT DIRECTLY TO THE DIODE .M.35 mm) wire and crimp the connector with a standard electricians pliers. replace the alternator. output. The direct current (D. 11 FUSE HOLDER IF BULB DOES NOT LIGHT OR LIGHTS WHEN POLARITY REVERSED. .24.P. Check for bad battery. .) to direct current.35 mm) of insulation from the cut end of the wire and twist the strands together. Reconnect plug end (or spade connector (diag.) is used to provide a trickle charge for the battery. Remove 1/4" (6. 42 SPADE CONNECTOR SOLDERLESS CONNECTOR RED DIODE GREEN D. 3600 R.C. Test the A.P.5 Volts D.C. -11.C. Place the solderless connector from the new diode onto the exposed 1/4" (6.P.M.P. 3300 R.C.C.C.C.C. output check by pulling back the protective coating from the wire on the alternator side of the diode. wiring. . 3000 R.C.18.USE A HEAT SINK. .P. 3600 R. voltmeter. NOTE: DO NOT USE ACID CORE SOLDER. With the engine running minimum values should read: 2500 R. If one of these minimum readings are noted.0 Volts A. -10. If this is not available. proceed to make an A. Ground the other probe to the engine (diag. voltage before the diode using an A.C. the system is okay.0 Volts A.M.C. If low or no voltage is experienced.M.8.0 Volts D.3 AMP DC ALTERNATOR SYSTEM DIODE IN HARNESS SLEEVE This system has a diode included in the red wire which converts the alternating current (A.P. Place the probe (+) in the red wire lead connector. .5 Volts D. If no reading or less than the above reading. voltage.22. but the output readings will be the same. 3000 R.0 Volts A. To check D.C. With the engine running minimum values should read: 2500 R. DISCARD DIODE. replace with a six (6) AMP fuse. If faulty.C. disconnect at plug (spade terminal) and cut the wire on the opposite end of the diode at the solderless (crimped) connector.M.5 Volts D.M. replace the diode. separate the connectors at the engine. .P.P. New heat shrink tubing can be installed by slipping over the wires and heating with a hot air gun.C.C.C. The leads from the alternator and the type of connector may vary.26.9.M. 3300 R. tape the diode and connections with electrical tape. To replace the diode. If the alternator puts out the minimum A. CHECKING THE SYSTEM: Remove the fuse from fuse holder and check the fuse to make certain it is good.0 Volts A. etc. ammeter.
voltage for the lighting circuit.19.0 Volts A. 3300 R.M. Reinstall the blower housing.C. Test the charging system using the applicable " Checking the System " procedure listed in this section.5 AMP D.C. voltage check cannot be made with this system.0 Volts A. voltage test. proceed to make an A. INSERT PROBES INTO CONNECTOR SLOTS. voltmeter to the wire terminals at the regulator-rectifier (diag.C. YELLOW RED NOTE: D. RED LEAD DIODE 3 AMP D. the alternator is ok and the regulator-rectifier is defective.M. The yellow wire provides the A. To do this.C.26.C.C.M. Replace the diode if continuity exists after reversing tester leads or no continuity is found. system used to charge a battery with a 5 Amp A. the minimum values should read: 2500 R.P. .P. If the minimum values are noted. Alternator This unit combines a 3 Amp D. 15 43 . 14).C.C. 5 Amp A.C. BLACK LEAD 5 AMP A.C. DO NOT REMOVE CONNECTOR WIRES. Located in the red wire of the harness is a diode which converts the alternating current to direct current for charging the battery. 3000 R. and the regulator-rectifier must be brought outside of the blower housing.P.C.C. charging system to power an electric clutch without the use of a battery. 12).P. OUTPUT TEST. the blower housing must be removed. See Chapter 9 for "Disassembly Procedure".C.C.C. / 5 Amp A.C. ALTERNATOR SYSTEM REGULATOR-RECTIFIER UNDER BLOWER HOUSING CHECKING THE SYSTEM: An open circuit D.M. A wire harness( part # 36588) may be added to the 3 Amp D. OUTPUT MUST BE DISCONNECTED TO PERFORM A. . With the engine running. 15) Continuity should exist in one direction only.C. 3600 R. VOLTMETER CAUTION: BLOWER HOUSING MUST BE INSTALLED WHEN RUNNING ENGINE 14 3 Amp D. system used for lighting. Use the procedure for diode replacement found in the 3 AMP alternator test (diag. Test the diode in the harness by using a continuity test (diag. output connector at the wiring harness and connect the probes from an A. If a known good battery fails to maintain a charge.23. the alternator is defective. .C.28. A. CAUTION: AT NO TIME SHOULD THE ENGINE BE STARTED WITH THE BLOWER HOUSING REMOVED.0 Volts A.C. Disconnect the red D. .C.0 Volts A.C. If less than above readings.
25. 3300 R. Using an A.M. .C.15.C.P. (Red wire) 2500 R.M.8. 3000 R.13.M.C.C. DIODE RED A. 3000 R. voltage at the yellow wire terminal.P.M.P. P. (Yellow wire) 2500 R. wiring or switches.0 Volts D.M.20. C.M. .C.P.0 Volts A. . D.M.C. 3600 R.5 .C.C.5 Volts D.17.5 (Red between Engine and Diode) 2500 R. the minimum values should read: DIODE A.0 Volts A.C. pull back the protective shrink tubing from the diode.29.C. (Red wire) 2500 R. at the lead on the alternator side of the diode (diag.C.P.0 Volts A.17). A. D. YELLOW 17 Models OVM/OVXL/OHV12.P.26. 5 Amp A. YELLOW RED DIODE 16 MODELS OHV 13.P. .C.5 Volts A.M. .P.C. . If low or no voltage is experienced.M.0 Volts D. .8.0 Volts D. .M.M. voltmeter. 3600 R. .C.0 Volts A.C.P. With the engine running.M.0 Volts D. 3600 R.M.11. disconnect the plug and measure the D. Measure the A.CHECKING THE SYSTEM: To check the system. Check for defective lights.P. If the above minimum values are noted. C. . 16).18. . If less than above values are noted.P.0 Volts A.P.C. 3600 R.P.M.M. 5 Amp A. the minimum values should be: MODELS OVM/OVXL/OHV12. C. C.C. replace the alternator.C.M.C. the system is okay. .C.P.6.0 Volts A. . 18 44 . check the voltage going into the diode from alternator.0 Volts A. . 3000 R.5 3 Amp D.11. (Yellow wire) 2500 R. voltage at the red wire terminal (diag. .C.C. 3000 R.5 Volts A.22.C.9.13. 3000 R.0 (3/5 amp split) 3 Amp D.C 3600 R.11.0 Volts A. . With the engine running.0 Volts D.P.
P. With engine running.0 Volts A.C.17 (Read between Engine and Diode) 2500 R. 3600 R.C.C.5 Volts A. CHECKING THE SYSTEM: An open circuit D. 3600 R.0 Volts A. the blower housing must be removed. minimum A.P. . the alternator is okay.24. If a known good battery fails to maintain a charge. OUTPUT LEAD-RED MAGNETO GROUND . However.C. D.M. If the minimum readings are noted. . voltage. 3000 R.M. . Install the blower housing with the regulator-rectifier outside the housing.21. voltage test.0 Volts A. proceed to make an A. If the alternator puts out the minimum A.C.M. replace the alternator.P. Alternator System RegulatorRectifier Under Engine Housing In this system. replace the diode.C.17. To do this.M.M.GREEN 20 INSERT PROBES INTO CONNECTOR SLOTS DO NOT REMOVE CONNECTOR WIRES CAUTION: BLOWER HOUSING MUST BE INSTALLED WHEN RUNNING ENGINE YELLOW RED A. With an A. Keep the A. regulator styles are not interchangeable (diag. leads attached to the regulator-rectifier. voltage check cannot be made with this system.0 Volts A.C.19. and the regulator-rectifier must be brought outside of the blower housing.P.C.M. . Test procedures for all types are the same.C.C.P. VOLTMETER 21 45 . Various types of regulator-rectifiers have been used on different applications. . 3300 R. 21) CAUTION: AT NO TIME SHOULD THE ENGINE BE STARTED WITH THE BLOWER HOUSING REMOVED. 3000 R. .M. voltage from lead to lead should be: 2500 R. the regulator and rectifier are combined in one solid state unit mounted under the blower housing of the engine.C. If the system fails to charge a known good battery. . RED DIODE YELLOW 19 7 Amp D.5 .P.21.Models OHV 13.0 Volts A.C.C.16. A.C. If low or no voltage is experienced.C.C.C. 20). the regulator-rectifier is defective.0 Volts A. voltmeter probe the regulator as shown (diag.23.P.
C.P. 3600 R. OUTPUT TEST. Start the engine. If a known good battery fails to maintain a charge. 3000 R. .RED SOLENOID GREEN MAGNETO GROUND FUSE BATTERY LIGHT SWITCH VOLTAGE REGULATORS If a known good or load tested battery fails to maintain a charge.21 Volts A.C.0 Volts A. proceed to make an A.C.C. Disconnect the negative jumper lead and the plunger should return to the extended position. output check.C. if not replace the solenoid.C.C.C. 22 16 Amp Alternator System with External Regulator CHECKING THE SYSTEM: An open circuit D. . If less than above output. . the alternator assembly is defective.16. Place one lead of the A. A. Proceed to make an A. 46 23 SINGLE DOUBLE 24 .M. 24).26.C. OUTPUT YELLOW A.20. replace the regulator (diag. If less than the above values are noted. Set the voltmeter on the 0-20 Volt D.C. from the battery positive terminal to the (or one) solenoid terminal. OUTPUT YELLOW RED NOTE: D. the charging system and the regulator can be checked using a voltmeter. 3000 R.C.M.C. OUTPUT .C.31. D. 3300 R.C. minimum values should read: 2500 R.M.P. proceed to make an A. voltmeter to the wire terminals at the regulator-rectifier.C.C. the solenoid can be checked by removing the electrical plug-in at the base of the solenoid.M. the alternator is operating properly.10 Amp A.P. OUTPUT MUST BE DISCONNECTED TO PERFORM A.C. voltage check using the applicable procedure.C.C. Note the battery voltage.M. Connect a jumper wire from the metal housing (or other terminal) to a negative battery terminal. Disconnect the red D. Alternator CHECKING THE SYSTEM: Unplug the connector at the wiring harness supplied by the OEM. Test the solenoid off the carburetor by applying 12 volt D. See Chapter 9 for "Disassembly Procedure". The plunger should retract the full travel distance. With the engine running. voltage check cannot be made with this system. If no voltage increase is noted. voltage test. 23).0 Volts A. 22). AMMETER REGULATED D. . the voltage reading should increase from the noted battery voltage but not exceed 15 Volts D. the alternator is defective.0 Volts A. Almost immediately the engine should shut down. scale and connect the probes across the battery terminals. voltmeter on the center plug of the connector.22.C. If the minimum values are noted.C.C.P. . FUEL SHUT-DOWN SOLENOIDS If the engine is running. minimum values should read: 2500 R. Place the other lead to engine ground (diag.5 Volts A.C.. output connector at the wiring harness and connect the probes from an A.M. or the proper minimum A. voltage is noted during the check. Replace if necessary (diag.P. If the battery voltage exceeds 15 Volts D. With the engine running. .0 Volts A.C.P.C.
A bright blue spark should be seen at the tester. Remove the spark plug wire from the spark plug. If no spark is seen.LOW OIL SHUTDOWN SWITCHES Check the LOS switch while it is in the engine. Place the speed control in the run position. FLOAT SWITCH 25 LIGHTED ENGINE ON/OFF ROCKER SWITCH W/LOW OIL SHUTDOWN INDICATOR LIGHT TERMINALS (3) 27 26 ENGINE ON/OFF ROCKER SWITCH TERMINALS (2) SPACER 28 47 . Install a gap type tester connected to the spark plug wire and a good engine ground. replace the indicator light. Reinstall the blower housing and spin the engine over. If spark occurs now. and the oil level at the full mark. replace the LOS switch. remove the blower housing and disconnect the LOS lead from the ignition module. If not. Spin the engine over using the electric or recoil starter. If equipped. The engine must be level. the indicator light will flash if the oil level is at or below the add mark and the engine is turned over while attempting to start. If the indicator light does not flash. Test by turning the engine over with the oil level below the add mark. replace the ignition module.
Use the reverse procedure for assembly. the "O" rings on each end of the housing must be replaced.i. The response time of the sensor is between 5 and 15 seconds with 13 volts D. The oil pressure of a running engine should be above 10 p. Remove the two or four retaining nuts from the through bolts holding the cap assembly. Illustrations may not be identical in configuration to the starter being serviced. 29). Slide off the cap assembly. 4. (. at the battery. If continuity is found or the tractor oil pressure indicator light is on or comes on at low engine RPM's. 29 LOW OIL SENSOR This sensor must use a # 194 bulb in series with the sensor for proper operation and to prevent sensor damage. If lower than 10 p. 8. 30). Place the keyswitch in the run position.s. anti-drift spring.i.) BENDIX ASSEMBLY RETAINING RING DUST COVER THRUST WASHER RETAINER & SPRING BRUSHES GASKET ARMATURE 31 48 .700 bar).LOW OIL PRESSURE SENSOR Test the sensor on a running engine using an ohmmeter or continuity tester with one tester lead connected the sensor terminal (with lead wire removed) and the other to an engine ground. The terminal insulator slides out of the commutator cap (some models). Starters labeled UL listed/ CSA approved are serviceable. Remove the plastic dust cover on the bendix end (diag. 12 VOLT or 120 VOLT ELECTRIC STARTERS 1. 7. 5. Use teflon-type pipe sealant on the sensor threads to prevent oil leakage when reinstalling (diag. remove the sensor and check engine oil pressure with a master oil pressure gauge. (. but procedures and tests apply unless otherwise stated. 31). If internal service is necessary (non-CSA) starters only. ELECTRIC STARTER SERVICE 30 This section covers the service procedures for the 12 and 120 volt electric starters. and drive nut. The indicator light should come on with the tip of the sensor in air and go off when oil covers the sensor tip. An open circuit should be found with the engine running and continuity should exist when the engine is shut off.C. Lower battery voltage will result in a longer response time. Attach a jumper lead from an engine ground to the threaded portion of the sensor. Slide off the spring retainer. Inspect and replace as necessary. For diagnosis of the starting circuit see Electrical Starter Troubleshooting in this chapter. If a starter is serviced. 2. 6.700 bar). see the section "Inspection and Repair" later in this chapter. only replaced. an internal engine problem exists (diag. gear. place the armature into the brush end of the frame first. Remove the sensor from the engine and attach the electrical plug. ( For ease of assembly. 3.s. Remove the armature. Push down the spring retainer and remove the retainer ring. Starters labeled CSA cannot be serviced. scribe a line across the cap assemblies and armature housing to aid in reassembly.
49 . Rotate the armature by hand to check for binding before installation on the engine. If necessary the armature can be turned down in a lathe. While rotating. Replace parts as necessary. 34). and no continuity should exist between the field coil connections and the starter housing (diag. Secure the cap with the locking nuts and tighten the nut on the starter terminal post. 3. Brushes should be replaced if the brush wire approaches the bottom of the brush holder slot. 9. 2. 3. Light pressure and back and forth movement should be used. Install the thrust washer on the end of the armature and the install the starter end cap. Notice the position of the brush ground eyelet under the thru bolt flange. Attach one lead to each field coil connection. it should be washed in solvent (rubber parts cleaned in soap and water) to remove dirt and grease. If the gear does not engage or slips. Install the thru bolts while checking to make sure the bolts go thru the ground brush eyelet terminals.7 mm) of the solid field wires. Note or mark the position of the connectors of the brush wires. Remove the two nuts holding the driving end cap in place. and dried before reassembly. 5. Install and tighten the drive end thru bolt nuts. Route the wires to prevent damage during assembly. FIELD COIL CONNECTORS FIELD COIL CONNECTORS BRUSH SPRINGS 12 VOLT CONNECTION POINT OF POWER CORD LEADS 32 120 VOLT 33 34 35 Brush Card Replacement 1. Continuity should exist between each field coil connection. Scrape the insulating varnish off the last 1/2" (12. and remove the brush card assembly. 2. Remove the nuts holding the end cap in place. The armature should be checked for glazing or wear. Insert the new brush card into position while guiding the solid field wires through the proper slots in the brush card. Install the armature into the housing while spreading the brushes. 32 & 33). Check for continuity between the copper commutator bars and the iron of the armature. Crimp and solder the brush leads to the solid field wires. This prevents solder and heat from flowing up the brush lead. Recut the commutator bars to a depth equal to the width of the insulators between the bars. Brush springs must exhibit enough strength to keep tension on the brushes and hold them on the commutator.Inspection And Repair 1. Grasp the thru bolts using a vise grip positioned as close to the flanged end as possible to prevent thread damage. none should exist (diag. check the brushes for wear. The pinion gear parts should be checked for damage or wear. 35). The brushes and brush card holder should be checked for wear. 7. Use a needle nose pliers or vise grip to hold the woven brush lead close to the connector while soldering. Remove the armature and driving cap assembly. Loosen but do not remove the two nuts on the starter terminal post. 8. followed by the two thru bolts. 4. 4. polish the commutator bars using a piece of 00 sandpaper (diag. With the armature in place and the brushes engaging the commutator surface. Use a wire cutter to clip the solid field wires as close to the connectors as possible. Also check the armature and drive nut splines for wear or damage. Clean the accumulated dirt off all starter parts. Remove the end cap and the thrust washer. Insulate the crimped connection nearest the starter terminal post using electrical tape or heat shrink tubing. The field windings can be checked using a continuity light or ohmmeter. Note or mark the brush card in the starter housing. but do not overtighten. 6.
the Plus 1 or Parts Smart Look-up system. Consult microfiche card # 30. On nonelectric start systems.CHAPTER 7 FLYWHEEL BRAKE SYSTEMS GENERAL INFORMATION Tecumsehs brake systems are required to meet compliance standards which has become a federal law as of June 30. In order to restart the engine. A specified foot probe must not contact the blade when applied completely around the entire blade housing. 2. or Service Bulletin # 107 to determine the correct engine speed or blade tip speed. 2). 1. The blade must stop within three seconds after the operator lets go of the engine/blade control bail at the operator position and the engine is stopped. GROUND CLIP IGNITION GROUND WIRE GROUND CLIP IGNITION GROUND WIRE BRAKE PAD BRAKE "ON" 1 BRAKE "OFF" 2 50 . Use of the blade brake clutch in conjunction with a top mounted recoil starter or 12 volt electric starter. The blade must stop within three seconds after the operator lets go of the blade control bail at the operator position and the engine continues to run. OPERATION In the stop position the brake pad is applied to the inside edge of the flywheel.M. 1982. the engine/blade control bail must be applied. This system is available on recoil and electric start models. This method is acceptable if the mower deck passes the 360 degree foot probe test. This action pulls the brake pad away from the inside edge of the flywheel and opens the circuit to the ignition ground out terminal. Use of a recoil starter with the rope handle on the engine as opposed to within 24 inches (61 cm) of the operator position. at the same time the ignition system is grounded out (diag. On electric start systems the starter is energized by an ignition/start switch or a two motion control. Tecumsehs flywheel brake system provides consumer safety by killing the engine and stopping the lawnmower blade within three seconds after the operator releases the engine/blade control bail at the handle of the lawnmower. the recoil starter rope must be pulled to start the engine (diag. The engine stopping time is affected by the engine R.P. Starter rope handle is either on the engine or on the equipment handle. 1). Listed below are two methods used by original equipment manufacturers to meet compliance standards. This alternative can be used with engine mounted brake systems and typical bail controls.
Where a two motion control is used the interlock switch is utilized as the starter switch. 3). 51 . and a tension spring (diag. If there is a electric starter switch used to start the engine. the interlock switch acts as a safety switch and will not allow the starter to crank unless the engine/blade control bail is depressed. The control cable transfers the motion of the engine/ blade control bail to the brake system. The interlock switch is a push button switch that is activated by the brake lever when the engine/blade control is actuated. This stops the solid state module from firing the spark plug (diag. Remove the necessary components using steps 1-8 as outlined in Chapter 9 under "Disassembly". The ignition ground terminal is a plastic block with a wire extending out of it.COMPONENTS The brake bracket assembly consists of a replaceable brake lever and pad. Late production brake brackets are serviced as a complete assembly. The wire is connected to the ignition ground out spade on the solid state module. The brake spring supplies the pressure to the brake lever and brake pad to stop the flywheel. GROUNDING CLIP POSITION TOP VIEW LINKAGE BRAKE PAD 3 Ô MOUNTING HOLES MECHANISM FULL DOWN BEFORE SCREWS TORQUED Ô 4 ELECTRIC START INTERLOCK SWITCH SERVICE Service on part or all of the flywheel brake assembly will require a partial disassembly of the engine to allow the flywheel and brake bracket to be removed. and the ignition module is grounded. The brake lever contacts the wire of the ignition ground terminal when the engine/blade control bail is released. an ignition kill switch. 3).
MOUNTING HOLES Ô Ô MECHANISM FULL DOWN BEFORE SCREWS TORQUED 8 52 . or if there is less than .060" (1. Release the spring tension by unhooking the short end of the spring from bracket with a pliers. Be careful not to overtighten the screws as switch breakage can occur (diag. be certain that the screw length is not too long as to prevent free travel of the lever. Some slack should exist in the cable adjustment to compensate for brake pad wear (diag. No continuity should exist when the button is released. Rehook the link. This will properly align the brake bracket to the flywheel brake surface (diag. Slide the pad lever from the shaft and unhook the link. carefully grind the heads off of the rivets that fasten the interlock switch to the brake bracket. The brake pad is bonded to the brake lever and must be replaced as an assembly. To check the interlock switch. Inspect the brake pad for dirt. 8). IGNITION GROUNDOUT TERMINAL Inspect the terminal grounding wire for proper alignment and contact with the brake arm. continue by removing the alignment tool. The cable must provide enough travel so the brake will contact the flywheel. Make sure the button on the starter interlock switch is completely depressed when the control is fully applied. If the pad is contaminated. BRAKE PAD 5 Ô MOUNTING HOLES MECHANISM FULL DOWN BEFORE SCREWS TORQUED Ô 6 ELECTRIC START INTERLOCK SWITCH CONTROL CABLE If replacing the cable conduit screw with a screw other than a service part replacement. To replace the interlock switch. check for less than 3 second stop time. When completed.524 mm) thickness of brake pad material at the pad's thinnest point. SCREW END MUST NOT BLOCK LEVER ACTION CABLE CLAMP SCREW 7 BRAKE BRACKET REPLACEMENT When installing a inside edge brake bracket assembly. Install the interlock switch onto the brake bracket in the proper position and secure the switch to the brake bracket with the machine screws supplied. install the brake lever and pad assembly. use an ohmmeter or continuity light to perform a continuity check. Remove the E clip from the brake pad shaft. On serviceable brake brackets. Use the self-tapping screws supplied with the new switch to make threads in the bracket. 6). If the switch fails replace the switch (diag.BRAKE BRACKET ASSEMBLY Late production brake brackets are serviceable only by installing a complete brake bracket assembly. Remove the rivets from the back side of brake bracket. 6). 5). replacement is necessary. GROUNDING CLIP POSITION TOP VIEW LINKAGE STARTER INTERLOCK SWITCH The engine/blade control must close the interlock switch before the starter can be engaged. be sure the slotted holes in the brake bracket are all the way down on the fasteners. 7). Insure that all electrical connections are clean and secure (diag. Disconnect the wires off the switch before performing a continuity check. install the "E" clip. oil or grease contamination. rehook the short end of the spring and continue to reassemble the brake system in the reverse order of disassembly. Continuity should exist between the two terminals when the interlock switch button is completely depressed.
The outside electrode is grounded and secured to the threaded sleeve. Everything except the flywheel magnets. allowing the energy stored in the capacitor to flow to a transformer where the voltage is increased from 200 volts to 25. key and the spark plug are located in a encapsulated ignition module. This system requires no maintenance other than checks of the high tension lead and spark plug. If necessary.CHAPTER 8 IGNITION GENERAL INFORMATION Overhead valve four cycle Tecumseh engines use solid state capacitor discharge modules to provide high voltage to fire the spark plug. pulse transformer. it passes past a trigger coil where a low voltage signal is produced.2). The modules look similar but are not interchangeable. electrical energy is produced in the module. 1). The center electrode is insulated with porcelain. COMPONENTS The solid state module is a complete unit that includes the laminations and spark plug wire. the correct replacement module should be found using the Master Technician's Parts Manual. OPERATION SOLID STATE IGNITION SYSTEM (CDI) As the magnets in the flywheel rotate past the charge coil. trigger coil. The two are separated by an air gap which creates a resistance. The solid state ignition system consists of flywheel magnets and a flywheel key. STANDARD PLUG OHV 1 2 53 . high tension lead. The spark plug is made up of two electrodes. This solid state (CDI) module is protected by epoxy filler from exposure to dirt and moisture. This is an all electronic ignition system with all the components located outside the flywheel.000 volts. This voltage follows along the high tension lead to the spark plug where it arcs across the electrodes and ignites the air-fuel mixture (diag. charge coil. a silicon controlled rectifier. As the magnet continues to rotate. 200 volts) until it is released by an electrical switch (SCR). This low voltage signal closes the SCR switch. capacitor. A large voltage from the module arcs the air gap which causes a spark and ignites the air-fuel mixture in the cylinder (diag. and a spark plug. The energy is stored in the capacitor ( approx. NOTE: Always consult parts manual for correct plug and reach.
or partially sheared. 7. Examine the ignition module and lamination assembly for cracks in insulation or other damage. disconnect the ignition grounding lead at the ignition module. the magnetic strength is satisfactory (diag. pitted or burned electrodes. check the ignition switch. 3 TESTING PROCEDURE 1. 5. If the engine will not start or run properly proceed to step #3.The flywheel with magnets provide the magnetic flux (or field) which is necessary to induce voltage and trigger the module to provide spark. Try to start and run the engine. 3). Ignition modules are permanently attached to the lamination and must be serviced as an assembly. 2.762 mm) air gap setting. Check the operation of the ignition module using an approved tester following the instructions furnished with the test unit. Remove the blower housing. Check for spark using a commercially available spark tester and following the tester's recommended procedure. Replace if questionable. Check the air gap between the flywheel magnets and the laminations of the ignition module. Hold a screwdriver at the extreme end of the handle with the blade down. Reinstall the blower housing and crank the engine over. which would cause shorts or leakage of current. Check the flywheel magnets for the proper strength using this rough test. excessive carbon buildup. or electrical wiring for shorting to ground. Tecumseh has some keys that look similar but affect ignition timing. or booklets offered by the Tecumseh Products Co. NOTE: Always replace flywheel keys by Model and Specification Number. It should be .3175 mm) or use gauge part # 670297.05 mm) MAGNETS 4 4. 3.05 mm) of the magnets. If the screwdriver blade is attracted to the magnets. If a flywheel key is sheared. 54 .0125" (. and proper . the engine will not start or can be difficult to start (diag.030" (. Engine and Transmission Group Service Division. Check the spark plug for cracks in the porcelain. 4). Attach the spark plug wire to the spark plug tester and ground the tester as in step #1. safety interlock switches. If spark occurs. The flywheel key locates the flywheel to the crankshaft in the proper position for ignition timing. 3/4" (19. 6. move the blade to within 3/4 inch (19.
check switches.FOUR CYCLE IGNITION TROUBLESHOOTING Engine Will Not Start Engine runs erratically or shuts off. check for shorts or grounds in wiring Disconnect ignition ground-out wire at the igniton module & repeat test Check electric starter and battery if applicable Check for proper air gap on ignition module and repeat test Check flywheel magnets for strength Test ignition module 55 . wiring and equipment controls Engine problem. restarts Check for spark Spark No Spark Replace spark plug Check for the correct spark plug Isolate engine from equipment and repeat test Spark No Spark Check flywheel and key for damage or sheared key Set proper air gap on ignition module Test ignition module for intermittent or weak spark Equipment problem.
Faulty piston rings. or 1/2 of a turn further if using a new spark plug. BLOW OUT THOROUGHLY WITH COMPRESSED AIR. 4. see Chapter 9 under "Disassembly". Oil level is too high. NOTE: DO NOT USE A SAND BLASTER TO CLEAN PLUGS. 7. Restricted exhaust system. MICROSCOPIC PARTICLES LEFT IN THE PLUG CAN SCORE THE ENGINE CYLINDER DURING OPERATION. If a torque wrench is not available. 3. or if the porcelain is cracked anywhere.030" (. Incorrect spark plug gap. AND USING EYE PROTECTION. or the breather is restricted. 10. GAP GAUGE (670256) SPARK PLUG SERVICE Spark plugs should be removed. Improper fuel. 8. Install the spark plug in the engine and tighten it to 180 inch pounds (20.5 Nm) torque. Carburetor setting is too rich or the air cleaner is restricted. Weak ignition system. and use a spark plug wrench to turn the spark plug 1/8 to 1/4 of a turn further if using the old spark plug. Incorrect spark plug. 2. screw the spark plug in as far as possible by hand. USE A SOLVENT AND A WIRE BRUSH TO CLEAN. Check the air gap with a spark plug gap gauge and adjust accordingly. 5 CONDITIONS CAUSING FREQUENT SPARK PLUG FOULING 1. 5. Normal Carbon Deposit Worn Oil Deposit 6 56 . and adjusted periodically. Set the spark plug gap at . cleaned. 9.762 mm) (diag. Poor grade of gasoline. Replace the plug if the points on the base of the plug are pitted or burned. When replacing a spark plug consult the parts breakdown for the correct spark plug to be used in the engine being serviced. When reinstalling the plug make sure it is clean of all foreign material. 6. 5). Partially closed choke shutter.SERVICE To remove the ignition module or the flywheel from the engine.
If the mixture is ignited too soon. The air gap check consists of having the proper . the spark must ignite the compressed air-fuel mixture when the piston is in a specific position to deliver maximum power. kickback can be experienced due to preignition. or an inability to start the engine with a good spark. Remove the air gap gauge and rotate the flywheel to check for any possible striking points. or spark plugs.1 meters) of an unshielded welder. If none are found. A partially sheared or the wrong flywheel key can cause kickback. This position is known as Before Top Dead Center (BTDC). the air gap is set correctly and the air gap check is completed (diag. Use a standard business card as an air gap gauge.IGNITION TIMING CHECK In order for an engine to run effectively and efficiently. . loss of power.0125" (. Use flywheels with cooling fins that are broken off. Check the flywheel key if one of these symptoms exist. See Chapter 9 under "Service" for the disassembly procedure. part # 670297 between the flywheel magnets and the laminations of the module while tightening the mounting screws to the proper torque. 7). If the mixture is ignited too late.0125" (.3175 mm) air gap gauge. Store a solid state module within 20 feet (6. Attempt to reglue the spark plug lead back into a solid state module. Timing on a solid state module is not adjustable. flywheel keys. loss of power can be experienced due to retarded spark.3175 mm) 7 SERVICE TIPS DO NOT: Interchange flywheels. 57 .
The engine camshaft gear is twice as large as the mating gear on the crankshaft to allow proper engine valve timing for each cycle. As the piston starts to the top of the cylinder. OPERATION 4-CYCLE ENGINE THEORY All 4-cycle engines require four piston strokes or cycles to complete one power cycle. cylinder head. valve train. piston and rod assemblies. 1). camshaft. As the piston reaches the Before Top Dead Center (BTDC) ignition point. 2. cylinder cover. The expanding gases force the piston down (diag.CHAPTER 9 INTERNAL ENGINE AND CYLINDER GENERAL INFORMATION This chapter covers the cylinder block. The crankshaft position is designated as either horizontal or vertical as the engine rests on its base. The piston is traveling downward creating a low pressure area. counterbalance systems. 3. 1. crankshaft. The intake valve is open and the exhaust valve is closed. As the piston reaches Bottom Dead Center (BDC) the intake valve closes. the exhaust gases are forced out (diag. After the piston reaches Top Dead Center (TDC). The engines identified by decals or model as XL (Extra Life) or XL/C (Extra Life / Commercial ) are made using aluminum alloy diecast around a cast iron cylinder liner. INTAKE. EXHAUST. The piston then rises. 4. igniting the air-fuel mixture. drawing the air-fuel mixture from the carburetor into the cylinder area above the piston (diag. COMPRESSION. flywheel. 1 2 3 4 58 . The crankshaft makes two revolutions for every camshaft revolution. the piston has moved to Top Dead Center (TDC) ready to take the full combustive force of the fuel for maximum power during downward piston travel. breather. In the time it takes to ignite all the available fuel. POWER. The flywheel or the equipment load on the crankshaft provides the inertia to keep the engine running smoothly between power strokes. 2). All Tecumseh engines covered in this manual are four cycle engines with the valves in the engine head. and lubrication systems. compressing the air-fuel mixture trapped in the combustion chamber due to both valves being closed (diag. not all engines with cast iron cylinder liners are identified as XL or XL/C. the spark plug fires. The exhaust valve opens. The governors and the governor systems are covered in Chapter 4. However. 4). During this piston stroke both valves remain closed. the four cycle process will begin again as the piston moves downward and the intake valve opens. 3).
and other internal parts (diag. It uses a lobed gear in a rotating ring to provide positive oil displacement (diag. Oil is pumped from the bottom of the crankcase. see " Engine Assembly Procedure " in the Service section of this chapter. The oil dipper is either bolted on or may be cast on to the cap with one of the rod bolts (diag. A dual shaft counterbalance is also used on some engine models. For timing of either counterbalance system. Oil under pressure lubricates the top crankshaft main bearing and camshaft upper bearing (diag. A gear on the crankshaft drives the counterbalance with the thicker gear. 6). This system uses a single weighted shaft that is driven off the crankshaft. This shaft's function is to counteract the imbalance caused by the counterweights on the crankshaft (diag. the eccentric moves the barrel back and forth on the plunger forcing oil through the hole in the center of the camshaft. On all Tecumseh vertical shaft 4-cycle engines. 8). COUNTERBALANCE SHAFT GOVERNOR FLANGE CAMSHAFT 10 59 . the oil is sprayed out under pressure through a small hole between the top camshaft and crankshaft bearing to lubricate the piston. 5). 10). 9). up through the camshaft and over to the top main bearing. connecting rod. which in turn drives the second counter balance shaft. A crankshaft drilling also provides oil to the crankpin journal on engine models OHV 13.5 -16.LUBRICATION SYSTEMS The lubrication system used with all Tecumseh horizontal crankshaft engines covered in this manual utilize a splash type system. 7).5. SPRAY MIST HOLE FLAT DIPPER SPRAY MIST HOLE CRANKCASE PASSAGE PLUG CRANKSHAFT OIL PASSAGE 6 MAIN BEARING OIL GROOVE CAMSHAFT DRILLED CAMSHAFT PASSAGE BARREL TYPE LUBRICATION PUMP 7 ASSEMBLE PUMP HOUSING WITH INSIDE CHAMFER TOWARD CAMSHAFT GEAR 8 OIL DRAIN HOLE NOTE: INSTALL OIL PUMP AFTER THE SUMP IS ON 9 5 DRIVE GEAR COUNTERBALANCE SYSTEMS Some Tecumseh engines may be equipped with an Ultra-Balance® counterbalance system. The ball on the end of the plunger is anchored in a recess in the cylinder flange (diag. As the camshaft rotates. All vertical shaft engines use a positive displacement plunger oil pump or a rotary oil pump. An oil dipper on the connecting rod splashes oil in the crankcase to lubricate all internal moving parts. The rotary pump is driven by the camshaft. The plunger style oil pump is located on an eccentric on the camshaft.
The cylinder block houses the piston, crankshaft, and along with the cylinder cover all the internal components. The block is a one piece diecast aluminum alloy cylinder casting which may have a cast iron liner (diag. 10). The piston transmits the force of the burning and expanding gases through the connecting rod to the crankshaft. The piston rings provide the seal between the cylinder wall and the piston. The rings keep the combustion pressures from entering the crankcase and also wipe the oil off the cylinder wall and return it to the sump. The connecting rod assembly is the link between the piston (piston pin) and the crankshaft. The cylinder head is a one piece aluminum alloy casting that is bolted to the top of the cylinder block. The overhead design contains all of the valve train except for the camshaft, lifters, and push rods. The crankshaft converts the up and down piston movement to the rotational force (torque) by an offset crankpin or rod journal. The camshaft lobes push the lifters at the proper time to allow air and fuel in and exhaust out of the cylinder. Teeth on the camshaft gear time the camshaft to the crankshaft. The valves allow air-fuel mixture to enter the cylinder and exhaust gases to exit. The valves provide a positive seal when closed. The valve springs return the valves to the closed position and must be strong enough to maintain valve lifter and cam lobe contact. The valve retainers lock the spring to the valve stem. The valve lifters maintain contact on the camshaft, move the push rods to pivot the rocker arms and move the valves. The crankcase breather is a one way check valve that allows air out and prevents air from coming in. It allows the engine to develop a partial vacuum in the crankcase during operation. The cylinder cover provides the bearing surface for the power take off (P.T.O.) end of the crankshaft and camshaft. This bolted on cover is removed to provide access to all internal components. The oil pump (vertical shaft only) consists of a steel plunger and a nylon or aluminum housing that rides an offset on the camshaft. The rotary pump consists of a lobed gear in a rotating ring that is driven by the camshaft. The flywheel provides the mass to smooth the effects of one power stroke every other crankshaft revolution. Flywheels are made of aluminum alloy or cast iron. The flywheel fins act as a fan to cool the engine.
Associated equipment loose or improperly adjusted
Excessive engine loading
Fuel cap vent obstructed
Check for excessive carbon in combustion chamber
Low oil level or wrong viscosity oil
Dirty carburetor or air filter
Loose flywheel examine key, key way and proper flywheel nut torque
Cooling air flow obstructed or clogged cooling fins
Carburetor improperly adjusted
Ignition timing or incorrect spark plug
Carburetor improperly adjusted or improper RPM setting*
Governor sticking, binding or improper RPM setting
Loose or worn connecting rod
Ignition timing or incorrect spark plug
Carburetor linkage, shafts or shutters sticking or binding
Worn cylinder
Carbon in the combustion chamber
Intermittent spark, check ignition or incorrect spark plug
Lean carb setting causing overheating (adjustable carb)
Oil level above full
Piston rings worn
Wrong viscosity oil
Worn or glazed cylinder
Excessive engine speed
Valve guides worn excessively
Engine cooling fins dirty causing overheating
Breather damaged, dirty or improperly installed
Damaged gaskets, seals or "O" rings
Carburetor improperly adjusted
Bent crankshaft
Oil level too high
Wrong or fouled spark plug
Attached equipment out of balance
Excessive RPM or improper governor setting
Valves sticking or not seating properly
Loose mounting bolts
Damaged gaskets, seals or "O" rings
Ignition timing or incorrect spark plug
If applicable counter balance not properly aligned
Breather damaged, dirty or improperly installed
Excessive carbon build up
Piston rings not properly seated or ring end gaps are aligned
Improper Valve Lash Weak valve spring
Angle of operation too severe
Air intake obstructed
Lack or lubrication or improper lubrication
Carburetor improperly adjusted
Exhaust Obstructed
Improper valve lash
Loss of compression (worn rings, blown head gasket)
Check the ignition module operation using a gap type tester installed between the high tension lead and spark plug. Check the spark plug for the proper application or a fouled condition. 3. 3. or crankshaft key damage. Tighten the flywheel nut to the proper torque. SURGES or RUNS UNEVENLY 1. crankshaft journal) for excessive clearance. Check valve lash. Make sure the engine is not being overloaded. settings found on microfiche card # 30 according to the engine model and specification number.Service. Check the blade hub. Remove excess load (sharpen blades. See Chapter 8 under "Service.P. Check the oil level and viscosity. and the spark plug for proper reach and heat range (correct spark plug for the engine). Replace if any damage is evident. setting using a vibratach or other tachometer and compare it to the R. 4. See Chapter 8 "Ignition . Remove the cylinder head and check for excessive carbon in the combustion chamber.M. See Chapter 3 under "Service. 2. Check the fuel cap to make sure it is venting. settings found on microfiche card #30 according to the engine model and specification number. Check the engine R.M. ENGINE MISFIRES 1. limit operation speed. Remove. 3. Recut the valves and seats if questionable. Remove the cylinder head to check for excessive carbon buildup or a leaking head gasket. Replace if questionable. Check for intermittent spark. 2. ENGINE OVERHEATS 1. Check the ignition timing. Visually check all linkages. process less material). replace if necessary. or pivot points for binding. Check the flywheel key and the flywheel and crankshaft keyway for wear or partial shearing. See Chapter 3 under "Service. Clean or replace as necessary. 6. Remove the blower housing. clean and reinstall. 63 .TESTING ENGINE KNOCKS 1.M. Check the carburetor adjustment or clean the carburetor. See Chapter 10 under "Specifications". 2. Adjust as necessary. or crankshaft coupler for loose fit. cylinder.P. Check for carbon buildup in the combustion chamber." 5. Also check that the head gasket fit is correct. Check the ignition timing. Check for clogged cooling fins or obstructions to the air flow. Inspect the valves and valve seats for leakage. Replace or clean the air filter. Reinstall and re-torque the bolts to the proper torque. Check the carburetor for correct adjustment or remove and clean the carburetor using tag wire and compressed air. 2.P. connecting rod. Add or replace as necessary." 3. Check the engine R. Adjust as necessary. 5. blade adapter. Check for scoring or discoloration on the valve stem in the valve guide area." 4. Loosen the cap and retry engine operation. Check for the proper valve lash using a feeler gauge. 5. 6.M. setting using a vibratach or other tachometer and compare it to the R. Check the governor shaft." 7. Reset the carburetor following the adjustment procedure or clean the carburetor. Check the internal components (piston. inspect.P. loose bolts. 6. See "Valve Service" in this chapter. 4. 5. Check for the correct ignition module air gap. throttle shaft. See Chapter 3 under "Service." 4.
determine the cause of weak compression: worn rings. 11 EXCESSIVE OIL CONSUMPTION 1. and oil condition. 3. Check the oil level. Significant deflection will cause a vibration problem.P. Check the breather for damage. 3. 2. 3. settings found on microfiche card # 30 according to the engine model and specification number. BREATHER PASSING OIL 1. Check for leaking or damaged gaskets. If the engine is equipped with a counterbalance shaft.M.M. make sure the engine is not overfilled. or leaking valves. Also verify that the viscosity rating on the container of the oil being used is to specification. 2 and 4-CYCLE RPM SETTINGS 30 NOTE: MICROFICHE CARD 30 RPM'S ARE NOT ON PAPER NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS. using a vibratach or other tachometer and compare it to the R. overheating the engine. however. 2.M. Check the angle of operation. leaking head gasket. Replace and fill to the proper level.ENGINE VIBRATES EXCESSIVELY 1. Check the engine compression using a compression tester. the leak may prevent the engine from achieving a partial crankcase vacuum. Clean the cooling fins to prevent overheating.M.P. 6. or improper installation. or "O"-rings. square or a dial indicator.M.P. 5. 6. as necessary. Adjust as necessary. determine the cause of weak compression: worn rings. Remove and check the attached equipment for an out of balance condition. 4. 9. Check the engine R. 64 . If the engine has weak compression. or leaking valves. dirty condition. 5. Adjust the high and low R. seals. the leak may prevent the engine from achieving a partial crankcase vacuum. however. Check the valve guide clearance for excessive wear. Follow the compression tester's procedure. The oil return hole(s) must face down. 8. check the gear timing to determine if the counterbalance is out of time. Remove the spark plug wire. seals. 2. make sure they are tight. Check the engine crankshaft on the PTO end for bends using a straight edge. The computer parts lookup systems also have RPM information listed in each individual engine parts list. Check the breather for damage. Follow the compression tester's procedure. Check the engine compression using a compression tester. Check for leaking or damaged gaskets. Check the engine R.P. leaking head gasket.M. Avoid prolonged use at a severe angle.P. oil viscosity on the container of the oil being used. Check the angle of operation. setting using a vibratach or other tachometer and compare it to the R. 7. Avoid prolonged use at a severe angle. or "O"-rings. External leaks may not be evident. 4.P. Check the carburetor setting causing a lean running condition. or improper installation. If the engine has weak compression. Blades or adapters must be removed. 4. setting for excessive R. External leaks may not be evident. Check the engine mounting bolts. Check the oil level. The oil return hole(s) must face down. dirty condition. settings found on microfiche card # 30 according to the engine model and specification number.
1/2" / 12. A flywheel puller (part # 670306) may be used on flywheels with cored holes (diag. NOTE: DO NOT USE A JAW TYPE PULLER. Check the air intake for an obstruction (dirty filter. 7. 9. 7. oil saturated filter. Actual procedure may vary." 4. washer. 5.875 mm use part # 670314. 6. and tap sharply and squarely on the knock-off tool to break the flywheel loose. See Chapter 3 under "Service. SERVICE DISASSEMBLY PROCEDURE The following procedures apply to most engine models. 3. Replace the valves if necessary. oil viscosity on the container of the oil being used and oil condition. Drain or shut off the fuel supply. 4. and starter cup.LACKS POWER 1. other debris). 11/16" / 17. Thread the appropriate flywheel knock-off tool (7/16" / 11. Use a part # 670305 strap wrench to hold the flywheel from turning (diag. 5/8" / 15. Relieve the compliance brake pressure on the flywheel if applicable. 2. 6. Compress the spring by moving the lever toward the spark plug end and when the hole in the lever aligns with the hole in the bracket secure the lever in this position with alignment tool part # 670298. 13). Check the exhaust port or muffler for a restriction preventing proper exhaust flow. Drain the oil from the crankcase. If necessary. Disconnect the high tension lead from the spark plug. Locate the piston at Top Dead Center (TDC) on the compression stroke for easier valve train service.112 mm use part # 670103. then unthread it one complete turn. Remove the blower housing by first unscrewing the screw holding the dipstick tube to the blower housing and removing the remaining bolts holding on the blower housing. rotate the flywheel a half turn and repeat until it loosens (diag. Check the ignition timing. Check the engine valve lash.7 mm use part # 670169. Recondition the valves and seats. Remove the air cleaner assembly. Check the valves for proper seating and valve guide clearance. 12).462 mm use part # 670329) on the crankshaft until it bottoms out. Reset the valves at the proper lash. Lift upward under the flywheel using a large screwdriver while avoiding contact with the alternator coils or magnets. Check the flywheel key for partial shearing. Unplug the ignition kill wire from the terminal on top of the ignition module and unbolt the ignition module. Readjust the carburetor or remove the carburetor for cleaning. See "Cylinder Head and Valve Train Service" in this chapter. or some models require taps upward with a soft face hammer loosening the plastic tank wedges in the blower housing slots. 5. METAL HAMMER SOCKET WRENCH FLYWHEEL FLYWHEEL TOOL 12 KNOCK OFF TOOL SCREWDRIVER TO RAISE FLYWHEEL 13 14 65 . Remove the flywheel nut. 2. 3. Remove the spark plug. Replace and fill to the proper level. 1. 14). Fuel tanks may be held on with bolts. Check the oil level. Remove the fuel tank if it is attached to the engine. 8. screws.
Next to prevent valve or piston damage turn the piston down in the cylinder. Remove the crankcase breather if necessary. 12. head bolts. rocker arm bearings. spacer if equipped. On engine models OHM. retainers. caps. and push rods. and baffle plate. valve stems. push rods. and head gasket. Remove the rocker arm nuts or rocker arm bearings followed by the rocker arms. head. head gasket and valves. retainers. the valve springs. and the carburetor. 13.05 mm) deep socket over the valve cap and strike the top with a steel hammer (diag. rocker arm studs. Use a 3/16" Allen wrench and a 7/16" wrench on OHH. Remove the head bolts.10. with independent cylinder head and rocker box. 15). 14. Remove the jam nut. guide plate. Be careful not to bend or damage the linkage when removing. YOU MUST HAVE IT BACK IN BEFORE REASSEMBLY. and retainer screw must be removed to allow the rocker box to separate from the head. Remove the flywheel key and alternator if equipped. adjusting nut. and the rocker arm retainer screw. rocker arms. OVM. OVRM and OHV 11-13 use a 1/2 wrench. Then place a 3/4" (19. and push rod tubes. Remove the rocker arms by loosening the two locking nuts or allen head screws. head. Remove the intake pipe. OVXL and OHV.17 use a 3/16" allen and 1/2" wrench. The push rod guide plate must be removed to access one of the head bolts. 15 66 . Remove the muffler. Remove the rocker arm housing. and valve springs. 11. OHSK120. guide plate. Mark the hookup points or diagram the linkage arrangement to aid in reassembly. This action loosens the cap.5 . Notice the "O"rings used to seal the rocker box . Remove the head by first removing the valve cover. NOTE: ON SOME OHV ENGINES THE EXHAUST PUSH ROD CAN ONLY BE REMOVED AFTER THE HEAD IS OFF. OHV13. Remove the cap.
Remove the cap. remove the auxiliary shaft from the cover by removing the retaining ring and sliding the shaft out of the washers and drive gear. one at a time. remove any carbon from the top of the cylinder bore to prevent ring breakage. with thumbs. retainers. Remove the cylinder cover or mounting flange using a seal protector positioned on the seal to prevent seal damage. 20). 17. WORM GEAR OIL SLEEVE TOOL MOUNTING FLANGE OIL SEAL 16 GEAR 17 18 OIL SEAL REMOVED SNAP RING 19 BEVELED TOOTH TIMING MARK CRANKSHAFT GEAR CAMSHAFT GEAR 20 21 67 . 19. OHH engines with a ball bearing on the P. On all other overhead valve engine models. and valve springs. 20. 16. This action loosens the cap. 19). turn the crankshaft to roll the reduction shaft gear off the crankshaft worm gear when removing the cylinder flange (diag.15. 17. and counterbalance shaft or gears if applicable. Remove the lifters. The valve springs must be assembled on the same valve they are removed from (diag. Align the timing marks on the camshaft and crankshaft gears and remove the internal components (diag. 21). Push the piston out the top of the cylinder bore. On engines equipped with 8-1/2 :1 gear reduction. For engines equipped with 8-1/2:1 gear reduction. 18. place a 3/4" (19. Slide the large opening in the retainer toward the valve stem to remove (diag.O. The crankshaft must be free of rust or scale to slide the cover or flange off the crankshaft. Before removing the piston. Remove the valves from the head on models OHH and OVRM by supporting the valves with fingers while compressing the valve springs. rod cap. 18. 15).T. end of the crankshaft require the oil seal and the snap ring to be removed prior to the cylinder cover removal. 16.05 mm) deep socket over the valve cap and strike the top with a steel hammer.
If cylinder oversizing is needed we recommend boring the cylinder.010" or . Measure in the piston travel area approximately 1/2" to 3/4" (12.508 mm) oversize.7-19. Tecumseh recommends 380 grit for finish in a standard cross hatch. If the main bearing is worn or scored it can be replaced on some models. clean the stones with a wire brush when the hone is removed. See "Crankshaft Bearing Service" in this chapter. Rotate the adjusting nut so that the stones touch the cylinder wall and begin honing at the bottom of the cylinder. A light honing oil should be used to lubricate and cool while honing.254-. Measure at 90 degrees to the piston pin. use a commercially available hone of the proper size . move the hone far enough to extend the stones one inch beyond the top and bottom of the cylinder bore.M. Every fourth or fifth stroke. and dry thoroughly. Use a dial bore gauge or transfer gauge with a micrometer to accurately measure the cylinder bore. If the stones collect metal. the oversize value will be imprinted in the top of the cylinder (diag. rinse with clean water.127 mm) oversize. In some cases engines are built with oversize cylinders. Check the main bearing for wear or scoring. 68 . Lower the hone so the lower end of the stones contacts the lowest point in the cylinder bore. 45 degrees to the piston pin. If the cylinder bore is worn more than .010 . out of round or scored.P.450 crosshatch pattern. Replace the piston and the piston rings with the correct oversize parts as indicated in the parts manual. This service is offered by many Service Dealers.010 22 To recondition a cylinder. Move the hone up and down at a rate of 50 strokes per minute to avoid putting ridges in the cylinder wall. Continue the cleaning procedure until a clean white cloth wiped on any internal surface reveals no honing residue or dirt.CYLINDERS Visually check the cylinder for broken or cracked fins or a scored cylinder bore. 22). You also may wish to contact a local machine shop. soapy water.05 mm) from the top and the bottom . . it should be replaced or re-sized to . Chuck the hone in a drill press with a spindle speed of about 600 R. Check the bore diameter every twenty or thirty strokes for size and a 350 .005" (. If the cylinder is oversize. A rigid hone is recommended to "true" any cylinder irregularities. and even with the piston pin as the piston would appear when assembled.020" (. Start with coarse stones and center the cylinder under the drill press spindle. Clean the cylinder and crankcase with warm.
and OHV engines when the valves are removed for service.980" (50. If the spring has dampening coils. sealing. When servicing the valves. OVM.794 mm).067 mm) DAMPENING COILS LOCATED CLOSER TOGETHER THIS END MUST FACE TOWARD THE STATIONARY PART OF THE ENGINE (CYLINDER HEAD) ALL OTHERS 1.C.CYLINDER HEAD AND VALVE TRAIN SERVICE Check the cylinder head for warpage by placing the head on a precision flat surface.105" (28. Springs. Replace if necessary. or when excessive valve train noise is heard. Valve lash should be checked before removal of the engine head if any of the following conditions are experienced. Valves marked "I" are installed in the intake valve location.127mm). A small amount of honing oil on the sandpaper will make it easier to slide the head. the valve should be replaced (diag. The piston should be at T. The push rods should be checked for straightness and the ends for wear. OHSK80 . OHSK50 . If the valves have been checked and are in a usable condition. Valve lash (between the rocker arm and valve stem) should be set or checked when the engine is cold. The valve springs should be checked for both ends being parallel and the free length being at least 1.17. replace the head. on the compression stroke (both valves closed). Replace the springs if necessary. an engine kickback is experienced. See specification section. the smaller valve (head) is installed in the exhaust valve location. inspect the corresponding rocker arm socket or valve lifter for wear. 25).70 2 23 4 2 Valves.D. Valve condition is critical for proper engine performance. 1/32" (. a popping is heard through the intake or exhaust.292 mm for OHM. the valve face should be ground using a valve grinder to a 45 degree angle.794 mm) MINIMUM DIMENSION STEM 5 1 3 TORQUE SEQUENCE OHV 11 .130 MARGIN 450 FACE 6 24 25 FREE LENGTH OVRM/OHH/ OHSK50-70 1. 23 & 24). And Push Rods The valves should be checked for proper lash. Always replace the head gasket and torque the head bolts in 60 inch pound (6. If after grinding the valve face the margin is less than 1/32 of an inch (. If warped in excess of .292 mm) 26 69 .980" (50. 1.7 Nm) increments in the numbered sequence torques in specification section (diag. OHM. 26). OHSK. Valves are not identical. If the push rod ends are worn or damaged.067 mm) for OHH and OVRM engines. If the valves are unmarked. Valves marked "EX" or "X" are installed in the exhaust valve location. OVXL. the valve spring should be installed with the dampening coils away from the valve cap and retainers (diag. 3 1 5 4 TORQUE SEQUENCE OVRM / OHH. all carbon should be removed from the valve head and stem.005" (. Slight warpage can be corrected by placing a sheet of #400 wet /dry sandpaper on a precision flat surface and rubbing the head gasket surface in a circular pattern until the entire gasket surface shows evidence of sanding. and wear.105" (28.
the cylinder wall should be de-glazed using a commercially available de-glazing tool or hone. The oil control ring can be installed with either side up. 27). Place a new compression ring squarely in the center of the ring travel area.254 mm) OVERSIZE PISTON PISTON MEASUREMENTS ARE TAKEN AT BOTTOM OF SKIRT 900 FROM WRIST PIN HOLE 27 Piston Rings After the cylinder bore diameter has been checked and is acceptable to rebuild. Ring side clearance should also be checked with a feeler gauge when using new rings with an old piston (diag. An outside notch (diag. If scoring or deep scratches are evident. Use a ring expander to remove and replace the rings. When installing new rings in a used cylinder.PISTONS. replace the piston. CYLINDER PISTON PISTON RING 28 29 CHAMFER 1ST COMPRESSION RING 2ND COMPRESSION RING 3RD OIL CONTROL RING Piston Ring Orientation If the top compression ring has an inside chamfer. The expander (if equipped) end gap and the ring end gap should be staggered (diag. 28) and measure the gap with a feeler gauge. 30). The rule to follow is an inside chamfer always faces up. NOTE: Always stagger the ring end gaps on reassembly. AND CONNECTING RODS Piston The piston should be checked for wear by measuring near the bottom of the skirt 90 degrees from the piston pin hole with a micrometer. The second compression ring will have either an inside chamfer or an outside notch. 30 EMISSION RINGS 1ST COMPRESSION RING 2ND COMPRESSION RING 3RD OIL CONTROL RING 31 70 . an oversize piston will be necessary. The ring end gap must be within the specification to have adequate oil control (diag. this chamfer must face UP. Visually inspect the piston skirt area for scoring or scratches from dirt ingestion. Replace the rings in sets and install the piston. Do not spread the rings too wide or breakage will result. rings. This procedure will assure correct piston ring end gap measurement. If the cylinder bore needs re-sizing. 29). 31) will face down or towards the skirt of the piston. and rod assembly in the cylinder bore with the ring end gaps staggered. 31).010" (. Use the piston upside down to push the ring down (diag. RINGS. Check the ring side clearance using a feeler gauge with a new ring. INDICATES . the ring end gap should be checked using new rings. Oversize pistons are identified by the imprinted decimal oversize value imprinted on the top of the piston (diag. Clean all carbon from the piston top and the ring grooves before measuring.
Check for bends on the P.130. or out of round condition at the bearing surfaces.70 engines use serviceable MCR components and must be assembled as illustrated in "Assembly" with a thrust washer placed on the camshaft next to the compression release weight. Inspect the cam lobes for scoring or excessive wear. OHSK120 .17 engines. and OVXL. CAUTION: NEVER TRY TO STRAIGHTEN A BENT CRANKSHAFT. OHH and OHSK50 . scratching. scoring. NOTE: Some OHH models used on chipper/ shredders may not require a compression release. On all engine models. the piston can be installed either direction on the connecting rod. ARROW DIRECTION 32 MATCH MARKS MATCH MARKS 33 BEVEL CHAMFER TOOTH CRANKSHAFT GEAR 34 CRANKSHAFTS AND CAMSHAFTS Inspect the crankshaft visually and with a micrometer for wear. oil dippers are attached to the bottom connecting rod bolt. the piston will have an arrow stamped on the top of the piston. Clean the camshaft with solvent and blow all parts and passages dry with compressed air. square or a dial indicator. The arrow on the top of piston or on the piston skirt must point toward the push rods or the carburetor side of the engine when installing it in the cylinder. On OHV 13. an arrow is found on the piston skirt. On engine models OVM.O. CAMSHAFT GEAR TIMING MARK PUNCH MARK SMALL HOBBING HOLE 35 CRANKSHAFT Camshafts Check the camshaft bearing surfaces for wear using a micrometer. (diag. end using a straight edge. If a damaged camshaft is replaced. Some engines have the oil dipper cast in the rod cap. The timing marks on the camshaft and the crankshaft gears must be aligned for proper valve timing. Consult the specification chart for the proper rod bolt torque when installing the cap. 33 & 34). When installing the connecting rod to the piston it is imperative that the rod be installed correctly. making sure that the pins and counterweights are operating freely and smoothly on mechanical compression relief types. the mating crankshaft and governor gear should also be replaced. If the crankshaft gear is pressed on it is not serviceable and the crankshaft must also be replaced.5 . the match marks on the connecting rod and cap must align and face out when installing the piston assembly into the engine (diag. (diag.CONNECTING RODS Some engine models have offset piston pins (not centered) to centralize the combustion force on the piston. GEAR KEYWAY CAMSHAFT GEAR SMALL HOBBING HOLE 36 COMPRESSION RELEASE MECHANISM 37 71 . On horizontal shaft engines. The rod bolts should be torqued in 50 inch pound (5.T. 35 & 36). OHM. 32) If the piston does not have an arrow.65 Nm) increments until the specified torque is achieved.
The 60 degree cutter is Neway cutter # 111. 42).250" (6. 38). OVRM and OHH engines have a small combustion chamber and require the use of a special Neway cutter #103 for the 46 and 31 degree combination cutter. that extends above the intake or exhaust cam lobe. It is CRITICAL that the new valve springs be installed or lobe damage will occur on the camshaft. Re-cut the seat to move the contact area higher or lower if necessary and recheck the contact area. except those units that use extended camshafts which will continue to use a cast iron camshaft.325 mm) exhaust guide. use the 46 degree cutter to cut the seat to a width of 3/64" (1. The engine will now run at full compression (diag.35 mm) intake guide. 39). The tapered pilots required are. INTAKE EXHAUST 39 The recommended procedure to properly cut a valve seat is to use the Neway Valve Cutting System. CAMSHAFT COMPRESSION RELEASE COMPRESSION RELEASE SPRING THRUST WASHER A INSERT SPRING END "A" B 38 Valve Seats Valve seats are not replaceable. Valve seats are ground to an angle of 46 degrees to a width of 3/64" (1. Third. Check the contact area of a new or reconditioned valve face on a finished valve seat. The ramp delays the intake valve closure. resulting in lower emissions and reduced compression for easier pull starting (diag. When the engine starts. Some OHH engines use a composite camshaft. which consists of three different cutters. First. This camshaft is used on OHH/OHSK 50-70 engines that have been manufactured after DOM (date of manufacture) 7048. to lift the valve to relieve the engine compression for easier cranking. The ramp is located on the backside of the intake cam lobe. centrifugal force moves the weight outward and the pin will drop back down.249" (6. Some OVRM engines use a ramp compression release (RCR) system that works with the intake valve. Consult the cutter's complete procedure guide for additional information. BOTTOM NARROWING CUTTER 150 600 SEAT BOTTOM NARROWING SEAT 3/64" SEAT 460 310 TOP NARROWING CUTTER TOP NARROW SEAT CUTTER 310 460 40 41 BOTTOM NARROW 42 72 . and Neway #100-1/4 for the . Second. Neway # 100-1/4-1 for the . If they are burned. 40).Mechanical Compression Release (MCR) camshafts have a pin located in the camshaft. This change that took place in February of 1997 and is basic on the OHH engines. use the 60 degree cutter to clean and narrow the seat from the bottom to the center (diag.191 mm) (diag. or distorted they can be regrounded using a grinding stone or a valve seat cutting tool. Using fingers. use the 31 degree cutter to clean and narrow the seat from the top toward the center (diag. NOTE: You must install the thrust washer between the cover and cam to prevent wear. snap the valve sharply against the corresponding valve seat and view the line imprinted on the valve face. A camshaft kit replaces the old camshaft and includes compression release components and two light tension valve springs.91 mm). The contact area or line should be continuous and appear on the upper 1/3 of the valve face. pitted. 41).
The valve lifters may be slightly different lengths.VALVE LIFTERS When removing the lifters. Oil temperature must be 375o . Using a 1/2" (12. GUIDES HEAD OIL HOT PLATE 3. and OVXL have valve guides that can be reamed 1/32" (. Heat the container on a hot plate approximately 15-20 minutes until the oil begins to smoke. Refer to the "Table of Specifications" (Chapter 10) to determine the correct oversize dimension. VALVE GUIDE REMOVAL (WHERE APPLICABLE. Heat the oil on a hot plate approximately 1520 minutes until the oil begins to smoke.2040C). It may be necessary to use a rubber or rawhide mallet to fully seat the new guide to the snap ring. The upper and lower valve spring caps must be redrilled to accommodate the oversize valve stems. the valve seats must be recut to align the valve seat to the valve guide. 2.794 mm) oversize valve stem. push the guide out of the head with the arbor press. VALVE GUIDE INSTALLATION 1. 5. CAUTION : USE PROTECTION FOR EYES AND HANDS.794 mm) oversize or be replaced as service parts.130. NOTE: DO NOT USE A STEEL HAMMER TO SEAT THE NEW GUIDE. 4. BE CAREFUL ! THE HOT OIL AND HEAD CAN EASILY CAUSE BURNS.24 cm) drift punch located in the center of the old valve guide. Do not allow the drift punch to contact the head during this step.7 mm) diameter. VALVE GUIDES Engine models OVM. Carefully drain the excess oil out of the head. Using a pliers. Using a pliers. GUIDE OR HEAD DAMAGE WILL RESULT. 5. 6" (15. BE CAREFUL ! THE HOT OIL AND HEAD CAN EASILY CAUSE BURNS. Reamers are available through your local Tecumseh parts supplier. The guides should be reamed oversize with a straight shanked hand reamer or low speed drill press.400oF (1900 . 3. CAUTION : USE PROTECTION FOR EYES AND HANDS. Oil temperature must be 375 o . 4. Insert the new guides in the head with the long end of the guides up. 6. 2. Submerge the head in a container of oil so that the valve guide bores are completely covered with oil. OHM.400oF (1900 2040C). If the guides get worn excessively. Visually check the lifter for wear on the cam contact surface and push rod contact surface. Place the head on a 6" x 12" (15. After oversizing the valve guides. remove the head from pan of oil. they can be reamed oversize to accommodate a 1/32" (. CONSULT PARTS MANUAL) 1.5 cm) piece of wood with the head gasket surface down. Place the valve guides in a freezer for an hour or longer to ease assembly. Submerge the head in a container of oil so that both guides are completely covered with oil. OHSK80 . 73 . Quickly work the next two steps while the head is hot to prevent damage to the guides or the head. Guides removed too cool will permanently damage the head HEAT UNTIL OIL BEGINS TO SMOKE 43 by removing aluminum necessary to hold the new guides in place. Install the snap rings on the new replacement valve guides. Quickly work the next two steps while the head is hot to prevent pressing the guides out with the head too cool. Place the head on the bed of an arbor press on parallels with the snap rings on the long ends of the guides facing down. Consult the tool section in Chapter 11 for the correct part numbers. All other overhead valve engines have valve guides that are permanently installed in the cylinder head. Carefully drain the excess oil out of the head. Allow the head to cool and re-cut both valve seats using a Neway cutter to align the new guides to the valve seats. remove the head from pan of oil. mark the lifters to install the lifter in the same position as it was removed from.24 x 30.
2 1 4 5 FILTER DRAIN HOLE GASKET COVER TUBE 46 BREATHER OUTLET TO CARB UMBRELLA 47 3 1 .Baffle/Gasket 5 . 44 45 GASKET COVER BODY REED BODY Side Mounted Breather This type of breather mounts over the valve compartment and uses a reed style check valve. When installing. If the plate has a notched corner. Make sure the small drain hole or holes are clean and installed down to allow return of oil back into the crankcase. 45). install the plate with the mark facing out.17 engines.Valve. Limit 3 . ELEMENT BAFFLE OIL RETURN PRESSURE OUT TUBE CHECK VALVE Top Mounted Breather This type of breather is mounted in the top and rear of the cylinder block in vertical shaft engines. side of the engine. The umbrella check valve allows positive pressure to be vented through the element and out the tube. 44). A new breather tube boot is recommended for replacement to assure proper crankcase seal. align the reed valve and plate parallel to the top surface of the breather opening in the crankcase.Screw 4 . install the notch toward the P.T. Use solvent and compressed air to clean the area if necessary. Hold the reed valve and plate in this position while tightening the screw.O. Apply engine oil to the breather tube boot and push the breather in until the top shoulder of the boot contacts the crankcase. Use a large flat blade screwdriver to pry the boot up and lift the breather assembly out. Most engines have the breather tube connected to the air cleaner assembly (diag. If the plate is marked. Late production OVRM engines use the rubber boot and breather tube as a "pop in" design.Cover 48 49 74 .Plate. Be careful not to drop the breather body out of the rubber boot when removing (diag. On OHV13. the drain holes must be open and be on the bottom.CRANKCASE BREATHERS The breather element and case can be cleaned using cleaning solvent. OHH engines use an umbrella valve type breather that is found in the rocker arm cover. Individual components are serviced only by the replacement of the complete cover.5 . Mark or note the location of the breather tube. Clean the internal element or reed area with solvent and compressed air if necessary. Reed 2 .
Replace as necessary. TAP IT INTO POSITION GENTLY UNTIL IT IS SEATED INTO ITS BOSS. AND BEARING SERVICE The following procedures. OIL SEAL REMOVER TOOL: POSITIONED FOR REMOVAL OF OIL SEAL OIL SEAL 50 OIL SEAL DRIVER 670272 OIL SEAL OIL SEAL DRIVER PROTECTOR CRANKSHAFT BEARING SERVICE Ball Bearing Service Remove the two bearing retainer screws and washers. Install a new ball bearing by pressing the bearing from the inside of the cover toward the outside until the bearing contacts the shoulder. looking for wear and scoring of the bearing surfaces. SOME SEALS ARE NOT POSITIONED FLUSH TO THE CYLINDER COVER. 50). except oil seal replacement. Select the proper seal protector and driver from the tool list in Chapter 11 to install a new oil seal. Always use new gaskets and new oil seals installed using seal protectors after the cover is removed.CYLINDER COVER. The seal protector will insure that the seal is driven in to the proper depth (diag. See "Engine Disassembly Procedure" in this chapter. remove the old oil seals by tapping them out with a screwdriver or punch from the inside. Measure the bearing surface diameters using a micrometer and check the specifications for worn or damaged parts. SNAP RING 51 OIL SEAL REMOVED 52 75 . remove the seal by using the proper oil seal puller (diag. OIL SEAL. WHEN INSTALLING A NEW OIL SEAL. When reinstalling the cover. Place the oil seal over the protector and place it over the crankshaft. Drive the seal into position using the universal driver part no. lbs. ATTEMPTING TO INSTALL THE SEAL TOO FAR IN CAN CAUSE DAMAGE TO THE OIL SEAL AND ENGINE. Remove the ball bearing in the cylinder cover by pressing the bearing from the outside of the cover toward the inside using an arbor press. 670272. apply a drop of Loctite 242 to the cover screw threads and torque the cover screws to the recommended specification. CHECK TO SEE IF THE SEAL IS RAISED OR RECESSED. 51). Install the two bearing retainer screws with washers and tighten to 45 in. If the crankshaft is in place. If the crankshaft is removed from the engine. Oil Seal Service NOTE: BEFORE REMOVING THE OIL SEAL. require the engine to be disassembled.0 Nm) of torque. (5. Cylinder Cover Clean and inspect the cover.
0000 . 1...2 mm) 34836 ........... Push the piston assembly in until the rod is positioned on the crankshaft rod journal surface..0005" (25................ Slide the crankshaft in until it bottoms..1................0010" (25...................413 ......1890" (30..34................1880 .......... 1.4 . 3.0000 ....1.......4 ............ Apply engine oil to the piston skirt..226 ...... Clean all internal engine parts with solvent and blow dry with compressed air or allow to dry.............................1.0000 ........... 1.............. Actual procedure may vary........413 ...........0005" (25.175 .......1........425 mm) 35377 ............SERVICE BUSHING We are supplying this bushing for service repair.. install the rod cap bolts and dipper if applicable and tighten the bolts in equal increments to the specified torque.3770" (34...... 4.................1......... 1............3765 ........ have a reputable machine shop do this work for you. Use new gaskets and seals at all locations.....250 mm) 31461 ....0005 .8760" (22................0005 ...... rings..413 mm) 33368 .. and the cylinder bore........ Using the correct seal protector (see Chapter 11 under "Tools")... After the bushing has been installed. and push the piston assembly into the cylinder with the match marks on the connecting rod facing out of the crankcase and the arrow on the top of piston or on the piston skirt pointing toward the push rod location or the carburetor side of the engine if applicable..... MATCH MARKS DURLOCK BOLT OIL SEAL PROTECTOR 53 54 76 ....1.................425 mm) 34837 ... 1. 1..22.....976 mm) ENGINE ASSEMBLY The following procedures apply to most engine models... stagger the ring end gaps. 1......1.............................950 ... connecting rod bearing surface. 1... apply engine oil to the crankshaft bearing surfaces and insert the tapered end of the crankshaft in the crankcase.........25........25................ 2..413 mm) 31462 ... 1.........1.... ... compress the rings......3765 ...25...976 mm) 35400 .......0005" (25.... BUSHING SIZE CHART BUSHING SERVICE PART NUMBER FINISHED REAM BORE DIAMETER 30979 ..........950 .....3770" (34............. it requires line reaming to the proper size... Using a band type ring compressor........0010" (25................413 mm) 31546 ...4 .........25........................ Align the match marks on the rod cap and rod.......... Following the chart below.8755 .......34.........25.......30...........
one may be added IF THE SUMP HAS AN OIL PASSAGE COVER. 58 ULTRA-BALANCE® TIMING 59 77 . Assemble the compression release components to the camshaft on engine models OHH and OHSK50-70.17 engines come equipped with a spin on oil filtration system. 55) NOTE: Some OHH models used on chipper/ shredders may not require compression release mechanisms. insert spring end "B" through the camshaft gear. camshaft. If the engine is not equipped with a filter.5. 7.C. Align the timing mark or notched tooth on the crankshaft gear to the mark or hole in the camshaft gear. Slide the drive gear over the keyway in crankshaft while aligning the timing marks on the gears. If equipped.C. CRANKSHAFT MATCH MARK THINNER GEAR THICKER GEAR COMPRESSION RELEASE CAMSHAFT COMPRESSION RELEASE SPRING THRUST WASHER INSERT SPRING END "A" A B 55 GASKET OIL PASSAGE GASKET SCREW OIL PUMP SHAFT OIL FILTER OIL PUMP ASSY. Some OHV11 . 6. "O" RING OIL PUMP COVER OIL PASSAGE COVER SCREW CHAMPFER UP TOWARD CAM 56 DUAL SHAFT COUNTERBALANCE 57 CAM TIMING a.D. Slide the drive gear over the keyway in the crankshaft while aligning the timing mark with the thicker counterbalance gear.). (diag. barrel and plunger style oil pump (chamfered side toward the gear) if applicable. Assemble the thrust washer on the camshaft next to the compression release.D. Install spring end "A" through the release from the pin side. Install the counterbalance with the thicker gear in the far right boss in the crankcase and the other counterbalance shaft with the thinner gear in the far left boss while aligning the timing marks. The kit part number 36435A should be ordered to upgrade the engine if desired. DRIVE GEAR. and slide the release pin in the small hole near the center of the cam gear. Install the lifters. ultra-balance shaft or dual balance shafts if applicable. Dual Balance Shaft Time the dual shaft counterbalance system with the piston at T. time the Ultra-balance® with the piston at Top Dead Center (T. NOTE: Engines equipped with rotary oil pumps must have the drive shaft and pump assembled after the sump cover is installed.
9.5 -17 engines. Use a small block to support the valves tight to their seats while placing the head on a flat surface. 10. 670315 63 . OVM. place the push rods in the block before installing the head and head gasket. 65 on page 79). Compress the spring and install the valve retainers to lock the valve to the valve cap.1 mm) of the stud is exposed.8 Nm) increments to the specified torque.8. 11. followed by a new "O" ring and the pump cover. Repeat the procedure for other valve. install the oil pump drive shaft into the slot in the end of the camshaft.5 . Do not force.8 Nm) torque. OVXL (diag. and either turn the stud in or secure with a locking nut as shown so about 1-1/2" (38. Repeat the procedure for other valve. Mount the cylinder cover or flange with the governor gear assembly installed to the crankcase using dowel pins to position the cover and a new gasket. Use spring compressor tool part # 670315A installed on a rocker arm stud. On engines with ball bearings in the cover. On OHV 13. For models OHH and OVRM. Install the cover down onto the crankcase and slightly rotate the crankshaft to allow the governor gear to mesh. Install the cylinder head using a new head gasket. NOTE: Tecumseh strongly recommends you order a complete seal kit. 78 RING SHAFT ROTOR ROTARY PUMP 60 NOTE: INSTALL OIL PUMP AFTER THE SUMP IS ON 61 62 RETAINERS HELD BY SPRING TENSION AGAINST THE CAP RETAINER CAP VALVE SPRING COMPRESSOR TOOL PART NO. Replace all "O" ring and gaskets in kit. Rotate the crankshaft to place the piston at Top Dead Center (TDC) on the compression stroke. Apply a drop of blue Loctite 242 to the cover screw threads and tighten to the specified torque. Tighten the screws to 50-70 inch pounds (5. For OHV models. install the springs (dampening coils toward the head) and retainers on the valves and use fingers to compress the springs until the notch in the retainer is located in the notch in the valve stem. Tighten the head bolts in the numbered sequence using 60 inch pound (6. never only lap the seats. OHSK80-130. NOTE: Always cut the valve seats. Install the breather assembly. install a thrust washer (if applicable) over the crankshaft. Apply engine oil and install the oil pump ring and rotor. place the springs (dampening coils toward the head) over the valve guide and place the valve caps on the springs with the larger opening away from the springs. Pre-assemble the valves and spring assemblies into the cylinder head on all engine models EXCEPT OHM. On OHV 11-13 models. followed by the retaining ring.
Use a 12 inch (30. Bolt the valve spring compressor tool part # 670315A on a rocker arm stud using the rocker arm bearing and locking nut (diag. OVM / OHM STYLE 65 d. valve springs with the dampening coils toward the head. 670315 f. Install the new o-rings (white o-ring on the exhaust guide) followed by valve spring caps. 66). Install the valve box to head retaining screw using a flat washer and a new "O" ring. RETAINERS HELD BY SPRING TENSION AGAINST THE CAP RETAINER CAP e. 66 79 . 64) and valve spring retainers with the larger opening away from the engine. Compress the valve spring with the tool and insert the two retainers into the keeper so the inside ridge of the retainer locks into the valve stem groove. Use lubricated new "O" ring seals for both ends of the push rod tubes and install the push rod tubes in the crankcase. CONTINUE WITH STEP 13 FOR CURRENT PRODUCTION MODELS. Lift each valve up until it contacts the seat and hold the valve in this position.105 (28. (diag. a. g. DAMPENING COILS LOCATED CLOSER TOGETHER FREE LENGTH 1. VALVE SPRING COMPRESSOR TOOL PART NO. Install the push rods with the cupped ends of the rods placed on top of the lifters. STEPS 12A -12G APPLY ONLY TO EARLY PRODUCTION ENGINE MODELS OHM.067 mm) 64 (BLACK) b. Install the valves into the head. and using a new head gasket. push rod guide plate with the legs facing up. Repeat the procedure for the other valve (diag. place the head on the cylinder block. Tighten the head bolts in the numbered sequence using 60 inch pound (6.8 Nm) increments to the specified torque. NOTE: TORQUE THE CYLINDER HEAD FOLLOWING THE SEQUENCE ON PAGE 69. 66).5 cm) piece of fuel line and wedge one end on each side of the valve stem through the port opening to hold the valve. OHSK120.12. Visually check correct placement through the valve box opening. new rocker arm studs with "O" rings under the guide plate. Install the rocker arm housing.980" (50. Tighten the screw and the studs to the specified torque. TEFLON EXHAUST (WHITE) "O" RINGS c. OVM AND OVXL.292 mm) ALL OTHERS THIS END MUST FACE TOWARD THE STATIONARY PART OF THE ENGINE (CYLINDER HEAD) OVRM/OHH 1.
hold the rocker arm pivot bearing using a 7/16" wrench or socket while using a 1/2" crowfoot to tighten the lock nut to 120 in. (21. On OHV13. Adjust the rocker arm hex nut with a 1/2" wrench to set the correct valve lash and tighten the locking jam nut to 18 in.5 Nm). OHV110-145 models. tighten down the rocker arm studs to 190 in. Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag. install the guide plate with the rocker arm studs and torque to 190 in. OHM.5 Nm) of torque. and push rod guide plate (with the tabs up). OHSK80-130. lbs. Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag. Set the valve lash with the engine cold. 69)..D. with a 1/2" crowfoot. Adjust until a slight sliding drag is felt. and both valves closed. install the push rods on the lifters.5 Nm) of torque. washer. (2 Nm). Insert the specified feeler gauge between the rocker arm and valve stem. OHSK120 and OVXL. lock this position by holding an 3/16" Allen wrench on the pivot ball screw while tightening the lock nut to 120 in.5 -17 models. Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag. rocker arm bearings. lbs. install the rocker arms.C.13. (21. A 7/16" crowfoot will be needed to torque the lock nut. On models OVM. Tighten the adjusting nut until slight play exists. On models OHV 11-13. Turn the screws in until slight play exists between the valve stem and rocker arm. On engine models OHH and OVRM. (13. Insert the push rods in the lifter sockets with the longer steel end toward the rocker arms. Fasten the screw to the head with the push rod guide plate tabs facing up. Turn the screws in until slight play exists between the valve stem and rocker arm. OVM. 67). OHSK80-130. On OHV 11-13. and new rocker arm adjusting nuts on the studs. and rocker arms and lock nuts on the rocker arm pivot screws. place the rocker arms on the rocker arm screws followed by the locking nut. lbs. install the push rods on the lifters. OHV110-145. On OHM. Place the rocker arms onto the studs with the socket end toward the push rod and thread the rocker arm bearings on until excessive play is removed. 14. the piston at T. 68). lbs (13. On models OHH and OVRM.5 Nm). 3/16" ALLEN WRENCH 7/16" CROWFOOT WRENCH OHH / OVRM 67 LOCKING / ADJUSTING NUT CROWN DOWN "O" RING OR GASKET FEELER GAUGE VALVE STEM ROCKER ARM STUD OVM / OHM / OVXL PUSH ROD GUIDE TABS UP 68 7/16" SOCKET WRENCH 1/2" CROWFOOT WRENCH OHV 11-13 and OHV 110-135 / OHSK80-130 69 80 . OHSK120. and OVXL models. lbs.
175 hold a 1/2" wrench on the rocker arm bearing while tightening the 5/32" Allen head set screw to 75 in. 71). 15. 18. 20. Attach the backing plates or baffles. bevelled washer (concave surface in). Attach the governor arm lever if removed. Once adjusted use a 1/2" socket and torque the jam nut to 130 inch pound (14. and air cleaner assembly while hooking the throttle and governor linkage. speed control.0125" (. Use strap wrench part # 670305 to hold the flywheel and tighten the nut to the specified torque. starter cup (if applicable). Check the governor and speed control hookup and adjustment . Install the flywheel spacer if applicable. Attach the alternator coil if applicable and route the wires away from the flywheel area.see Chapter 4 under "Service". Install the intake pipe. and attach the ignition groundout lead at the control if applicable. Install the blower housing on all engines with intake pipe mounted speed control brackets.175 5/32" ALLEN WRENCH 1/2" WRENCH 70 1/2" WRENCH 71 . Rotate the crankshaft one full turn to check push rod movement and correct valve lash (diag. 17. remove the tool.3175 mm) AIR GAP 72 81 . and check for contact while rotating the flywheel. (8. None should be found.7 Nm).175 use a 1/2" wrench to tighten the rocker arm bearing to the correct valve lash. Install the ignition module using a part # 670297 . 21. lbs.0125" (. 19. 72).5 Nm) of torque. Install the blower housing on all engines with the speed control mounted on the blower housing or engine block. Tighten the mounting screws. Connect the breather hose to the valve cover fitting on model OHH.On models OHV 135 .3175 mm) air gap tool between the flywheel magnets and the laminations of the module (diag. flywheel key. flywheel. 16. carburetor. and flywheel nut. 1/2" TORQUE WRENCH OHV135 . 70). Rotate the crankshaft at least one full turn to check push rod movement and valve lash (diag. Attach the ignition ground lead to the module terminal. Install the rocker arm cover using a new gasket or o-ring and tighten the screws to the specified torque. Current production models OHV135 .
Tecumseh's tanks have a fuel filter in the tank and service is not necessary. Install the spark plug and high tension lead. verify top no load and idle RPM settings. Attach the fuel line and secure with clamps. replace the fuel filter. Mount the engine to the equipment and connect wiring and control cables. REMOVE BOLTS SLIDE TANK 73 82 .22. 24. Optimize the carburetor if adjustable. 26. NOTE: If the tank is supplied by the O. Slide the fuel line on the carburetor fitting and secure with a clamp. OVRM rotary mower engines require the blade to be secured to the blade hub adapter and crankshaft before attempting to start the engine. 25. Fill the engine with oil to the full mark on the dipstick. Attach the fuel tank (if applicable) using bolts or wedging the tank in the blower housing slots provided.M. Slide the breather tube on the carburetor or air cleaner fitting if applicable. Start the engine and allow it to run approximately five minutes to reach operating temperature. 23.E. Add fresh fuel to the fuel tank and secure the cap.
ENGINE SPECIFICATIONS AND SEARS CRAFTSMAN CROSS-REFERENCE The engine specifications listed on the following pages include tolerances that are considered acceptable to achieve normal engine operation. Observed values inside the listed tolerance range are satisfactory and require no adjustments.
143.366012 143.366072 143.366202 143.366212 143.366232 143.376012 143.376032 143.376072 143.376082 143.384132 143.384142 143.384152 143.384162 143.384182 143.384192 143.386012 143.386032 143.386092 143.386102 143.386152 143.386162 143.394092 143.394102 143.394112 143.394192 143.394202 143.394212 143.396012 143.396032 143.396062 143.396072 143.396092 143.396112 143.396132 143.404112 143.406012 143.406052 143.406062 143.406072 143.406132 143.406142
143.406152 143.406162 143.414432 143.416012 143.416042 143.416082 143.426092 143.426112 143.426122 143.426142 143.426152 143.426172 143.436032 143.436042 143.436092 143.436102 143.436132 143.436152 143.796112 143.806062 143.816042 143.836052 143.941200 143.941201 143.951600 143.951602 143.951602 143.955003 143.955007 143.961201 143.965007 143.965009 143.965011 143.965013 143.965015 143.965017 143.965019 143.965021 143.965023 143.965501 143.965503
143.971200 143.971201 143.971300 143.975003 143.975005 143.975009 143.975501 143.975503 143.976001 143.981200 143.981201 143.985001 143.985005 143.985501 143.985503 143.985505 143.986001 143.986003 143.986702 143.986704 143.986714 143.986716 143.986718 143.991200 143.991201 143.991203 143.991300 143.995007 143.996001 143.996005 143.996007 143.996009 143.996501 143.996503 143.996505 143.996507 143.996702
Specifications OVRM40 Standard English 9.06 1.844 2.500 2.501 .0125 .030 .004 .004 460 .035 .045
Displacement (in2) (cc) Stroke Bore
Metric mm 148.50 46.838 63.500 63.525 .3175 .762 .1016 .1016 .889 1.143
OVRM50-6.75 OVRM105 Standard Metric English mm 10.49 171.93 Note (A) Note (A) 1.938 2.625 2.626 Note (B) .0125 .030 .004 .004 460 .035 .045
OVRM120 Standard English 11.9 Note (A) 1.938 2.795 2.796 Note (B) .0125 .030 .004 .004 460 .035 .045
Metric mm 195.04 Note (A) 49.225 70.993 71.018 Note (B) .3175 .762 .1016 .1016 .889 1.143
OHH50 OHSK50 Standard Metric English mm 10.49 171.93 1.938 2.625 2.626 .0125 .030 .004 .004 460 .035 .045 .2807 .2817 .006 .027 Note (C) .9995 1.000 .9985 .9990 .9985 .9990 1.0005 1.0010 .4970 .4975 2.6204 2.6220 .0020 .0050 .0050 .0035 .0030 .0056 .007 .017 1.0005 1.0010 1.0050 1.0010 .889 1.143 7.135 7.155 .1524 .6858 Note (C) 25.362 25.400 25.362 25.375 25.362 25.375 25.413 25.425 12.624 12.637 66.558 66.599 .051 .127 .013 .089 .076 .142 .178 .432 25.413 25.425 25.413 25.425 49.225 66.675 66.700 .3175 .762 .1016 .1016
49.225 66.675 66.700 Note (B) .3175 .762 .1016 .1016 .889 1.143
Ignition Module Air Gap Spark Plug Gap Valve Clearance In./Ex. Valve Seat Angle Valve Seat Width Valve Guide Oversize Dimension Crankshaft End Play
.2787 7.130 7.079 .2797 7.155 7.104
7.130 .7.079 .2807 ..2787 7.130 .7.079 7.155 7.104 .2817 .2797 7.155 7.104
.006 .027 Note (C) .8610 .8615 .9985 .9990 .9985 .9990 1.0005 1.0010 .4975 .4980 2.4950 2.4520 .0020 .0050 .0050 .0035 .0040 .0058 .010 .020 1.0005 1.0010 1.0050 1.0010
.1524 .6858 Note (C) 31.869 21.882 25.362 25.375 25.362 25.375 25.413 25.425 12.637 12.649 63.373 63.378 .051 .127 .013 .089 .102 .147 .254 .508 25.413 25.425 25.413 25.425
.006 .027 Note (C) .9995 1.000 .9985 .9990 1.0005 1.0010 1.0005 1.0010 .4975 .4980 2.6204 2.6220 .0020 .0050 .0050 .0035 .0030 .0056 .010 .020 1.0005 1.0010 1.0050 1.0010
.1524 .6858 Note (C) 25.362 25.400 25.362 25.375 25.413 25.425 25.413 25.425 12.637 12.649 66.558 66.599 .051 .127 .013 .089 .076 .142 .254 .508 25.413 25.425 25.413 25.425
.006 .027 Note (C) .9995 1.000 .9985 .9990 1.0005 1.0010 1.0005 1.0010 .4975 .4980 2.6204 2.6220 .0020 .0050 .0050 .0035 .0030 .0056 .010 .020 1.0005 1.0010 1.0050 1.0010
.1524 .6858 Note (C) 25.362 25.400 25.362 25.375 25.413 25.425 25.413 25.425 12.637 12.649 66.558 66.599 .051 .127 .013 .089 .076 .142 .254 .508 25.413 25.425 25.413 25.425
Crankpin Journal Dia. Crankshaft Dia. Flywheel End Main Brg. Crankshaft Dia. P.T.O. Main Brg. Conn. Rod Dia. Crank Brg. Camshaft Bearing Diameter Piston Dia. Bottom of Skirt Ring Groove Side Clearance 1st & 2nd Comp. Ring Groove Side Clearance Bottom Oil Piston Skirt to Cylinder Clearance Ring End Gap Cylinder Main Bearing Diameter Cylinder Cover / Flange Main Brg. Diameter
Note A: OVRM60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a displacement of 11.9 (195.04). Note B: All OVRM 60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a 2.795"/2.796 (70.993/71.018) Bore. Note C: All engines equipped with a ball bearing will have "0" End Play.
Specifications OHH and OHSK55 - 70 Standard Metric English mm 11.9 195.04 1.938 2.795 2.796 .0125 .030 .004 .004 460 .035 .045 Valve Guide Oversize Dimension Crankshaft End Play .2807 .2817 .006 .027 Note (C) Crankpin Journal Dia. Crankshaft Dia. Flywheel End Main Brg. Crankshaft Dia. P.T.O. Main Brg. Conn. Rod Dia. Crank Brg. Camshaft Bearing Diameter Piston Dia. Bottom of Skirt .9995 1.000 .9985 .9990 .9985 .9990 1.0005 1.0010 .4970 .4975 2.7904 2.7920 .889 1.143 7.130 7.155 .1524 .6858 Note (C) 25.362 25.400 25.362 25.375 25.362 25.375 25.413 25.425 12.624 12.637 70.876 70.917 .051 .127 .013 .089 .076 .142 .178 .432 25.413 25.425 25.413 25.425 1.3740 1.3745 1.3745 1.3750 1.3745 1.3750 1.3775 1.3780 .6230 .6235 3.1195 3.1205 .0020 .0040 .0010 .0030 .0015 .0035 .010 .020 1.3765 1.3770 1.3765 1.3770 34.900 34.912 34.912 34.925 34.912 34.925 34.988 35.001 15.824 15.837 79.235 79.261 .051 .127 .0254 .076 .038 .089 .254 .508 34.963 34.976 34.963 34.976 .035 .045 .3432 .3442 .002 .042 49.225 70.993 71.018 .3175 .762 .1016 .1016 OHSK80 - 110 Note (D) Standard Metric English mm 19.43 318.46 2.532 3.125 3.126 .0125 .030 .004 .004 460 .889 1.143 8.717 8.743 .051 .067 70.993 79.375 79.400 .3175 .762 .1016 .1016
OHM, OHSK, OVM, OHV13.5 - 17 OVXL120,130 & OHV11-13 Standard Metric Standard Metric English mm English mm 21.82 357.63 29.9 490.06 2.532 3.312 3.313 .0125 .030 .004 .004 460 .035 .045 .3432 .3442 .002 .042 1.3740 1.3745 1.3745 1.3750 1.3745 1.3750 1.3775 1.3780 .6230 .6235 3.3095 3.3105 .0020 .0040 .0010 .0030 .0015 .0035 .010 .020 1.3765 1.3770 1.3765 1.3770 .889 1.143 8.717 8.743 .051 .067 34.900 34.912 34.912 34.925 34.912 34.925 34.988 35.001 15.824 15.837 84.061 84.087 .051 .127 .0254 .076 .038 .089 .254 .508 34.963 34.976 34.963 34.976 .042 .052 .3432 .3442 .0025 .0335 1.6223 1.6228 1.6245 1.6250 1.6245 1.6250 1.6234 1.6240 .6235 .6240 3.5595 3.5605 .0020 .0040 .0009 .0029 .0015 .0030 .012 .022 1.6265 1.6270 1.6265 1.6270 70.993 84.125 84.150 .3175 .762 .1016 .1016 3.00 3.562 3.563 .0125 .030 .004 .004 460 1.0671 1.321 8.717 8.743 .064 .851 41.206 41.219 41.262 41.275 41.206 41.275 41.234 41.250 15.837 15.850 90.411 90.437 .051 .127 .0229 .074 .038 .089 .305 .559 41.313 41.326 41.313 41.326 76.6 90.475 90.500 .3175 .762 .1016 .1016
Displacement (in2) (cc) Stroke Bore Ignition Module Air Gap Spark Plug Gap Valve Clearance In./Ex. Valve Seat Angle Valve Seat Width
Ring Groove Side Clearance .0020 1st & 2nd Comp. .0050 Ring Groove Side Clearance Bottom Oil Piston Skirt to Cylinder Clearance Ring End Gap Cylinder Main Bearing Diameter Cylinder Cover / Flange Main Brg. Diameter .0050 .0035 .0030 .0056 .007 .017 1.0005 1.0010 1.0050 1.0010
Note A: OVRM60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a displacement of 11.9 (195.04). Note B: All OVRM 60, 21000 spec. numbers with a "B" suffix and all OVRM 65, 22000 spec. numbers have a 2.795"/2.796 (70.993/71.018) Bore. Note C: All engines equipped with a ball bearing will have "0" End Play. Note D: For OHSK110 models with specification number starting with 223000 have a displacement of 21.82 ( 357.63 cc).
(Flanged) Muffler Mtg.5 204 Series In. OHH50-65 OHSK50-70 OVXL. (Rect. sufficient clamping force exists and a re-torque is not necessary. lbs.5 7.5 35 46 58 21 16.17. Mounting (Direct to Stud) Ign.120 6 86 .8 13 14 51 62 79 28 5 5 4.OVERHEAD VALVE TORQUE SPECIFICATIONS The torque specifications listed in this chart are to be used for replacing components after disassembly. torque are listed only as in. Muffler Mtg.) Muffler Mtg.5 5 11. However. Mounting (Direct to Cyl.5 13 8 2 8. Checking a torque value on a new or used engine may be lower due to torque relaxation that occurs on all engines from thermal expansion and contraction. lb. OVM. OHM. Intake Pipe to Head Carburetor to Intake Pipe Fuel Shut Off Solenoid to Carb.5 22. Rod Bolts Cyl. lbs. OHSK 2 BELLEVILLE WASHER (CROWN TOWARD BOLT HEAD) 3 TORQUE SEQUENCE OHV 11 . OHSK110 . Cover or Flange Flywheel Nut Flywheel Nut Cast Iron Flywheel Nut Spark Plug Ign. Cover or Flange Cyl.5 10. OVM. lbs.5 9 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 3 FLAT WASHER 2 4 1 5 5 1 4 TORQUE SEQUENCE OVRM / OHH. Rod Bolts Conn. OHM. Nm OVRM Cylinder Head Bolts Conn. not for checking an existing engine bolt torque. Mounting Stud to Cyl.5 - 26 12 24.) Ign. & OHSK OHV 11-13 OHV 110-135 206 Series OHV135-145 203 Series OHV15-17. Specifications below ten ft. (Oval) Muffler Mtg.3 9. measurements to encourage the use of an inch pound torque wrench for greater torque accuracy. Muffler (Flanged) to Manifold (Flanged) Muffler Clamp to Manifold 230 105 220 115 125 450 550 700 250 45 45 40 115 70 17 75 65 45 100 200 80 19 18. ft.
Coil Assy. measurements to encourage the use of an inch pound torque wrench for greater torque accuracy.5 4. to Cylinder Alt.5 204 Series 160 25 50 40 80 100 150 18 75 130 120 190 40 18 55 25 65 90 30 13. Coil Assy.5 21. lbs. However. lb. Checking a torque value on a new or used engine may be lower due to torque relaxation that occurs on all engines from thermal expansion and contraction. In. 87 .5 - 18 3 5. lbs. OVM OHSK & OHV 11-13 OHV 110-135 206 Series OHV135-145 203 Series OHV15-17. to Cylinder Alt.5 4.5 14. sufficient clamping force exists and a re-torque is not necessary.5 X X X1 X X X1 X X X X X X X X X X X X X X X X X1 X X1 X NOTE 1: A jam nut is described as a nut which is placed above the rocker arm and bearing.OVERHEAD VALVE TORQUE SPECIFICATIONS The torque specifications listed in this chart are to be used for replacing components after disassembly. (Shoulder Bolt) Recoil Starter Recoil Starter Recoil Starter Recoil Starter Electric Starter to Cylinder Electric Starter to Cylinder Rocker Arm Hex Jam Nut Rocker Arm Lock Allen Screw Rocker Adjusting Jam Nut Rocker Arm Stud Lock Nut Rocker Arm Studs Rocker Box Cover Rocker Box Cover Rocker Box Cover (4 screws) Alt.7 13. Coil Assy. A lock nut is positioned below the rocker arm and bearing.8 - 11 17 2 8. torque are listed only as in. Coil Assy. not for checking an existing engine bolt torque.5 2 6 3 7 10 3. to Lamination ft.8 10 15. Manifold Mtg. lbs.5 9 X X X X X X X X X X X X X X X X X 12. Specifications below ten ft. to Cylinder Alt. OHM. N/M OVRM OHH50-65 OHSK50-70 OVXL.5 10.
4-cycle engines. 695059 Understanding Tecumseh Ignition Systems. HH80. Detailing the teardown and reassembly procedures for the 800. 801 and 820 transaxles. Illustrates time saving features incorporated into the manual. This booklet is designed to be used as a work bench quick reference guide when servicing Tecumseh engines and motion drive systems. CARBURETOR TROUBLESHOOTING BOOKLET 695907 This booklet is designed as a quick reference to carburetion problems and related repair procedures. 2-cycle engines. VHS only. HH100. VIDEO PROGRAMS 695015 Carburetor Troubleshooting. 691462A Covers the diagnosis and repair of Tecumseh 4-cycle large frame engines. This video training program will assist the small engine technician in the proper procedures for troubleshooting electrical systems on outdoor power equipment. 2-cycle engines. OH120-180 Model numbers are located on the engine shroud. Except the TC Engine and TVS840. HH120. (Tests are similar for 98. Explains new carburetor parts breakdown format. 4-CYCLE ENGINE FAILURE ANALYSIS 695590 This booklet is designed as a tool for the average technician to correctly assess the cause of failure. A basic program designed to give the small engine technician first hand knowledge of Tecumseh ignition systems so the technician can understand the system and perform repairs to it. 695657 German Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines. possible problems and related repair procedures of Tecumseh Ignition Systems. 695148 Teardown and reassembly of the 900 series transaxles. 88 695185 Electrical Troubleshooting. 692509 Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines. 694988 Contains diagnosis and technical information for the repair of TVS840. 691218 Covers the diagnosis and repair of Peerless® power train components. AVAILABLE FOREIGN TECHNICIAN'S HANDBOOKS 694732 Spanish This manual covers the following models: VH80.) . SPECIAL TOOLS BOOKLET 694862 This booklet depicts all specialty tools offered by Tecumseh which can be used on 2 and 4 cycle engines and Peerless units. EDUCATIONAL MATERIALS AND TOOLS AVAILABLE TECHNICIAN'S HANDBOOKS 692508 Covers the diagnosis and repair of Tecumseh 2-cycle engines. Covers identification of carburetors used on Tecumseh engines and how to troubleshoot and repair them. 695562 French Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines. VHS only. 694530 Test procedures for Tecumseh electrical components using Merco-O-Tronic Tester 9800.CHAPTER 11. 694782 Contains technical information for the repair of the TC series. 695578 Covers the diagnosis and repair of the Vector Series. HSK/HXL845/850. SPECIAL BOOKLETS INSTRUCTIONAL GUIDE 692738 Assists in the use and understanding of the Tecumseh Master Parts Manual. TESTER BOOKLETS 694529 Test procedures for Tecumseh electrical components using Graham-Lee Tester 31-SM or 31-SMX-H. 695555 Spanish Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines. 695244A Covers the diagnosis and repair of the OVRM/OVM/ OHM/OHV 4-cycle overhead valve engines. 695285 An in-depth look at the 800 series transaxles. VH100. 910 and 920 series transaxles. IGNITION SYSTEMS TROUBLESHOOTING BOOKLET 694903 This booklet contains information on the identification. This video will show a complete step-by-step procedure for teardown and reassembly of the 900. 98A and 79. QUICK REFERENCE CHART BOOKLET 695933 This booklet contains the quick reference information found on Tecumseh wall charts.
Includes all items on this page but items may be purchased separately.TOOLS TOOL KIT 670195E Kit contains tools for 2. 89 .and 4-cycle engines.
670154A Valve lapping tool.Knock-off tool (right hand) (3/4"). for recessed. No. 670308. 670329 . 670156 Vibration tachometer. 13/16" crankshaft bearing diameters. No. 670292. No. No. 670287. No. 670169 . 1" crankshaft bearing diameters. No. Shaft. No. 35/64" 8-1/2:1 Aux. 670335. 670310. 670314 . No. 1-3/16" crankshaft bearing diameters. No.Knock-off tool (right hand) (5/8"). used with 670309. 13/16" crankshaft bearing diameters. 670261. No. 670263. 670331. 670312. No. 3/4" crankshaft bearing diameters.for recessed or flush seal position. No. No. 90 . 3/4" Crankshaft bearing diameters. 670309. 670289. 670277. 7/8" crankshaft bearing diameters. 670293. Adapter for raised or flush seal position. 670262. 670330. 670256 Taper Gap Gauge VALVE LAPPING TOOL No. use with 670308. Contains special tools commonly used in servicing 2 and 4 cycle engines. No. 1-3/8" crankshaft bearing diameter for recessed seal position. No. TAPER GAP GAUGE No. OIL SEAL PROTECTOR/INSTALLER Consult the specification chart or measure the shaft diamteter to determine the correct tool. 7/8" crankshaft bearing diameters assy.5" crankshaft bearing diameters. No. FLYWHEEL KNOCK-OFF TOOL Consult the specification chart or measure the shaft diamteter to determine the correct tool. No. 5/8" extended camshaft. Use with: No. 1" crankshaft bearing diameters assy.1-3/8" crankshaft bearing diameters. 670290. 670260. No. 670288. No. Use with: No. raised. 1-1/8" crankshaft bearing diameter recessed seal. No. 1-1/2" extended camshaft.Knock-off tool (right hand) (7/16"). No.1. or flush seal position. 670264.Knock-off tool (right hand) (1/2"). 1/2" extended camshaft. 670337. 670103 . 1-1/8" crankshaft bearing diameters. 1-3/8" crankshaft bearing diameters protector. 1" to be used with 670265 and 670266 recessed and raised. VIBRATION TACHOMETER No. No. No. 670195D Tool Kit.OIL SEAL DRIVER OIL SEAL REMOVER No. 670336.
Used on OVRM40-60 Exhaust valve guide. B. D.5 Intake and Exhaust. 1-3/8" main bearing. Oversize diameter .Bushing Driver/Installer. 670117 91 . 670284. OVM.3432/.079 .130 . None None No. No.7. 1/32" (.717 .5 SPEED ADJUSTMENT TOOL B. C.7. 670311 . 670298 Alignment Tool. A. No.104 mm).BUSHING TOOL KIT OVRM AND OHV11-16. 670328. 670326 Rebushing tool kit for use on OHM. No. Used on OHH on Intake and Exhaust.Bushing Driver/Installer.3442 (8. Oversize diameter . and OVRM40-60 Intake valve guide. TORX DRIVERS Torx 8 Torx 10 Torx 15 Torx 20 Torx 25 Torx 30 670334 670333 670323 670324 670319 670320 No. No.794 mm) OVERSIZE VALVE GUIDE REAMER RING EXPANDER No.155 mm) No. A. OHSK110.2807/. 670283.2787/.8. Used on OVXL/OVM/OHM120. OHV11-13 AND OVXL.743 mm). OVXL125 and OHV11-16. 670317 .2797 (7. C. 120.2817 (7. Oversize diameter .
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