This page has been translated with google translate, there may be errors in the stories.

The diesel engine consists of various parts that you cannot see from the outside, including crankshaft, pistons, connecting rod, valve mechanism. On the outside, these include alternator impeller pump, fuel pump, cylinder head. The cylinder head closes the cylinders at the top and there is a so-called head gasket between the block and the head.
The pistons move up and down and to convert this to a rotating movement, there is a crankshaft in the engine which in turn is coupled to the clutch and makes the propeller of the boat rotate.
A diesel is a 4-stroke engine, this means that a cylinder makes 4 layers of which 1 is the work stroke and actually provides propulsion, the other strokes are to let air into the cylinder, to push away combustion gases and the compression stroke. .
Because a diesel engine is a 4-stroke engine and therefore only after 4 strokes actual work is actually done, it is important that the diesel has a heavy flywheel, this ensures a more even running of the engine. As a rule, marine engines always have a heavier flywheel than car engines to make the engine run more smoothly.

The four strokes:

Intake stroke
During the intake stroke, the piston descends and the intake valve opens. Fresh air flows into the cylinder. The outlet valve is closed. During this stroke, the crankshaft turns half a turn.

Compression stroke
During the compression stroke, both valves are closed and the piston rises. This compresses the air in the cylinder. This creates a very high pressure and temperature above the piston. At the end of this stroke, the diesel is injected under very high pressure. The high temperature causes the mixture to self-ignite.

Labor stroke
After the compression stroke, the power stroke follows. During this stroke both valves are still closed. The piston is pushed down with great force. In this way the piston provides force (work).

Exhaust stroke
The last blow in the exhaust stroke. The inlet valve remains closed and the outlet valve is open. The piston rises and the spent gases can leave the cylinder.

Animation of a 4 stroke diesel engine.

The 4 strokes of a diesel engine.