Cold start (automotive)

Diesel engines do not use spark plugs to ignite the air fuel mixture and rely only on the heat generated by compression alone to ignite the fuel.

More effort is needed to turn over a cold engine for multiple reasons: The problem of cold starting has been greatly reduced since the introduction of engine starters, which are now commonplace on all modern vehicles.

The higher rpm that can be achieved using electric starter motors improves the chance of successful ignition.

Diesel engines make use of glow plugs to heat the combustion chamber prior to ignition, improving the conditions inside the engine, while certain manufacturers have incorporated a block heater, which heats the engine block prior to ignition to reduce the problem of cold starting.

In the early 1940s diesel engines fitted in tractors were started by use of a flamethrower to heat up the air that goes into the cylinder.