glow plugs start the engine in a diesel engine.
what do glow plugs do in a diesel engine?
start the engine
unlike gasoline and liquefied petroleum gas engines, diesel engines do not use high-voltage spark ignition (spark plugs). an engine running on diesel compresses the air inside the cylinder to high pressures and temperatures (compression ratios from 14:1 to 18:1 are common in current diesel engines); the engine generally injects the diesel fuel directly into the cylinder, starting a few degrees before top dead center (tdc) and continuing during the combustion event. the high temperatures inside the cylinder cause the diesel fuel to react with the oxygen in the mix (burn or oxidize), heating and expanding the burning mixture to convert the thermal/pressure difference into mechanical work, i.e., to move the piston. engines have glow plugs and grid heaters to help start the engine by preheating the cylinders to a minimum operating temperature. diesel engines are lean burn engines, burning the fuel in more air than is needed for the chemical reaction. they thus use less fuel than rich burn spark ignition engines which use a stoichiometric air-fuel ratio (just enough air to react with the fuel). as professor harvey of the university of toronto notes, "due to the absence of throttling [constant amount of air admitted, per unit fuel, with no user-determined variation], and the high compression ratio and lean fuel mixture, diesel engines are substantially more efficient than spark-ignited engines", generally; harvey cites the side-by-side comparisons of schipper et al. and the estimates of 20% lower fuel use and (given differences in energy content between fuel types) 15% lower energy use. gas turbine and some other types of internal combustion engines, and external combustion engine, both can also be designed to take diesel fuel.
diesel fuel
glow plugs have a limited lifetime and users are advised to have several replacement plugs on hand. replacement plugs must be the correct type; plugs for turbo engines are not compatible with plugs for standard engines. the plugs should be tightened a quarter-turn past a snug fit to avoid over-tightening. glow plugs, like all incandescent objects, are extremely hot, and glow plugs should never be removed when hot. likewise, care must be taken when fueling because a hot glow plug can ignite fuel. overheating of the battery can also be dangerous and only well-made connectors should be used.









































section::::technical specifications.
glow plug (model engine)