Push start

Push starting, also known as bump starting, clutch starting, popping the clutch or crash starting is a method of starting a motor vehicle with an internal combustion engine by engaging the manual transmission whilst the vehicle is in motion. The technique is most commonly employed when other starting methods (automobile self starter, kick start, jump start etc.) are unavailable.

The most common way to push start a vehicle is to put the manual transmission in second gear typically, switching the ignition to on/run, depressing the clutch, and pushing the vehicle until it is at a speed of 5 to 10 mph (8 to 16 km/h) or more, then quickly releasing the clutch to make the engine rotate and fire, then quickly depressing the clutch so it does not stall. This is done by one person pushing a lightweight automobile, pulling or being pushed by another vehicle or even rolling down a hill.

Push starting is most successful when the automobile is using a gasoline engine, uses a carburetor, and uses a capacitor discharge ignition (CDI) or an inductive discharge ignition system. Automobiles with other types of engine, ignition, and fuel delivery configurations may work, but may be more difficult to start. Some engines must have a battery providing some electricity since fuel injection systems must have power to operate.

A vehicle equipped with an automatic transmission (including semi automatic) is difficult to push start since selection of transmission gears is possible only when the internals of such a gearbox are rotating.

A diesel engine uses heat and high compression (compression ratios commonly 22:1 versus 9:1 for gasoline) to ignite the fuel. When normally starting a modern diesel engine, it typically uses glowplugs to preheat the cylinder(s). If a battery is completely discharged then it may not provide the necessary electrical power to 'glow' the glowplugs, making the push starting of a diesel vehicle with a dead battery almost impossible.

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