Diesel Engine Maintenance

In a conventional marine diesel engine power is produced by hot compressed air igniting fuel sprayed under very high pressure in the cylinder head. A marine diesel engine does not use a carburetor to mix fuel and air or spark plugs to ignite the mixture. Instead, it employs the pistons to compress air to 3000 kPa, which forced him to become very hot and the fuel ignited when it is injected into the cylinder.

Some marine diesel engines are equipped with a heater plug in the intake manifold or a candle in the pre-combustion chamber of each cylinder to provide additional heat to the combustion air during starting.

Diesel engines are heavier and slower than gasoline engines races but they are also more reliable because they do not rely on external carburetion or an electrical spark for ignition.

newer engines use a system of electronic fuel injection allowing fuel and air are mixed more thoroughly in the pre-combustion chamber before entering the cylinder. This system maximizes power and fuel economy and is also less polluting.

All boaters must have an understanding of how their engine works so start by explaining the mechanical cycles.

Most engines reciprocating internal combustion piston working on one of the two mechanical cycles-or four-stroke cycle or two-stroke cycle. These cycles mean in the right order, the mechanical actions by which the fuel and access of air into the engine cylinder, the gas pressure - due to combustion - is converted into power and, finally the burnt gases are expelled from the engine cylinder.

The basic diesel four-stroke

From its name, it is clear that there are four rounds in a complete cycle of the engine. A stroke is the piston motion throughout the length of the cylinder and - since one such movement causes the crankshaft to rotate half a turn - it follows that there are two crankshaft revolutions in one complete cycle engine.

The four strokes in the order in which they occur are:

1. time of admission. With the intake valve open and the exhaust valve closed, the piston moves from top dead center (TDC) to bottom dead center (BDC), creating a zone of low pressure in the cylinder. Clean, filtered air rushes through the intake valve open to relieve the area of low pressure, and the cylinder fills with air.

2. compression stroke. With both valves closed, the piston moves from BDC to TDC, compressing the air. Meanwhile, the air is heated to a temperature high enough to ignite the fuel.

3. stroke. About TDC, fuel is injected, or sprayed in the hot, compressed air, where it ignites, burns and expands. Both valves remain closed, and the pressure acting on the piston head, forcing it to the cylinder from TDC to BDC.

4. exhaust stroke. To BDC the exhaust valve opens and the piston begins to move from BDC to TDC, driving the burnt gas from the cylinder through the exhaust valve open.

The two-stroke diesel engine

The two-stroke engine uses two piston strokes to complete one power stroke and, therefore, fire twice as often as a four-stroke engine. A two-stroke engine is smaller and simpler with fewer moving parts. A two-stroke engine has the potential to produce twice as much power as a four-stroke engine of the same size, however, because of the additional facilities required in a two-stroke diesel engine, for example blowers and governors, they become more expensive to produce. There was a shift to four stroke diesel engines have become more efficient and smaller.

Protect your marine diesel engine

Protect your engine by avoiding long periods (more than 10 minutes) of idling in a "vacuum" situation. This is often done to charge batteries or cool refrigerants.