In a diesel engine, how is the fuel ignited?

In a diesel engine, fuel combustion is achieved through the heat of compression. This process occurs during the engine's compression stroke, where air is compressed to a high pressure and temperature inside the combustion chamber. The temperature can exceed 500 degrees Fahrenheit due to this compression. When fuel is injected into the highly compressed and heated air, it spontaneously ignites due to the heat rather than relying on a spark like in gasoline engines.

This method of ignition plays a crucial role in the operation of diesel engines, as it contributes to their efficiency and power output. Diesel engines are known for their robust performance and fuel efficiency, largely due to this self-ignition process that doesn't rely on an external spark source. Understanding this ignition method is fundamental for diagnosing issues in diesel engine mechanics and for performing maintenance effectively.