Key components of a diesel engine include the fuel injectors, glow plugs and solenoids, the air intake system, the crankshaft, and pistons and cylinders. A diesel engine is similar in many respects to a traditional gasoline engine, especially concerning components such as engine oil and coolant systems.
In a diesel engine fuel is injected to already-compressed air, increasing the ratio at which the fuel burns. This process means the fuel injectors are a critical part of a diesel engine, as is the timing of the pistons. To limit fuel injection, diesel engines typically have a governor on the fuel injection system.