Diesel fuel is ignited by heat caused by compression. The fuel is injected into the combustion chamber when the temperature of the compressed air charge is hot enough to ignite it. Glow plugs and various types of intake air heaters are used to assist starting a cold engine by pre-heating the air in the combustion chamber. You should NEVER use ether to start a diesel engine equipped with such devices as fire, engine damage or personal injury may result.
