while engine is shut off, which causes the cylinder to hydro-lock and possibly bend the piston connecting rod as well as other damage to engine when it is subsequently started. Cylinder head valve-guides do not have bronze sleeves, which allows for excessive wear and oil leakage around the valves. Connecting rods do not have bronze bushings where the piston wrist pin goes thru the connecting rod. This also allows for excessive wear and noise on higher mileage vehicles. If aftermarket tuning is installed that introduces too much advanced fuel injection timing, cracking of the cylinder heads can result due to excessive combustion temperatures. Very high cost of service and repair parts compared to other versions of the Power Stroke. Siemens K16 High Pressure Fuel Pump had a problem of self destruction in the 6.4L Powerstroke. When the pump destroyed itself, shrapnel would almost always be sent to all eight injectors, basically rendering them just as useless as the destoyed pump. On occasion, an injector may become stuck open and burn a piston crown, resulting in more repair work. Cracking pistons was a problem and usually started on the thin edge of the fuel bowl on the pistons. It occurred more frequently in high-mileage engines, and if left untreated for too long, more engine damage could occur. 6.7 Power Stroke The 6.7 L Power Stroke debuted in the 2011 Ford Super Duty (F-250 through F-550) trucks, replacing the 6.4 L Power Stroke. The first Power Stroke engine to be developed and manufactured by Ford, it was designed in conjunction with AVL of Austria. During its development, Ford engineers codenamed this engine "Scorpion" because of the exhaust manifold and turbocharger being mounted in the engine's "valley." It features a compacted graphite iron (CGI) block for greater strength and reduced weight, reverse flow aluminum cylinder heads (the exhaust ports are located in the lifter valley) with dual water jackets, six head bolts per cylinder, and high-pressure common rail Bosch fuel system. The system delivers up to five injection events per cylinder per cycle using eight-hole piezo injectors spraying fuel into the piston bowl. This engine also supports B20 biodiesel, allowing fueling options of up to 20 percent biodiesel and 80 percent petroleum diesel. Garrett's single-sequential turbocharger features an industry-first double-sided compressor wheel mounted on a single shaft. The engine block is cast by Tupy, which also does the initial machining. The connecting rods