How a diesel engine works (Opel Vectra A)

In a diesel engine, clean air is sucked into the cylinders and compressed to high pressure, reaching the ignition temperature of diesel fuel. As the piston approaches TDC, diesel fuel is injected into the cylinders under high pressure, which spontaneously ignites.

When the engine is cold, the temperature of the compressed air does not reach the ignition point of the fuel. In this case, the cylinders must be preheated. For this purpose, glow plugs are located in the swirl chambers of the cylinders. In addition, the diesel engine has a starting device that sets the injection advance regulator in the high-pressure fuel pump (HPFP) to an earlier injection. As a result, the fuel is injected into the hot air earlier, and the cold engine starts better. As soon as the temperature in the cylinders reaches the value required for fuel ignition, the starting device automatically switches off.

Fuel is sucked by the injection pump directly from the fuel tank and supplied under pressure of about 135 bar. It is distributed to the cylinders in the order of their operation.

The amount of fuel injected is controlled by the accelerator pedal. The fuel is supplied at the right time to the swirl chamber of the corresponding cylinder and sprayed by the nozzle. The swirl chamber has a shape that optimally mixes the air with the injected fuel.

Before fuel enters the injection pump, it passes through a fuel filter, being cleaned of impurities and water. The filter must be replaced in a timely manner.

Text was copied from the portal [opelbook.ru]

The high-pressure fuel pump does not require maintenance. All moving parts of the pump are lubricated with diesel fuel. The pump is driven by a toothed belt, which also drives the camshaft. Since the diesel engine does not have an ignition system, it cannot be shut down by disconnecting the high voltage from the spark plugs (as in a gasoline engine). To stop the engine, a special electromagnetic valve is provided, which closes the fuel supply channel when the ignition is turned off.