Yanmar GM Diesel Inboard Repair Manual One, Two & Three Cylinder Engines, 1980-2009

• 1GM Single-Cylinder Diesel Engine
• 1GM10 Single-Cylinder Diesel Engine



• 2GM Two-Cylinder Diesel Engine
• 2GMF Two-Cylinder Diesel Engine
• 2GM20 Two-Cylinder Diesel Engine
• 2GM20F Two-Cylinder Diesel Engine



• 3GM Three-Cylinder Diesel Engine
• 3GMF Three-Cylinder Diesel Engine
• 3GMD Three-Cylinder Diesel Engine
• 3GM30 Three-Cylinder Diesel Engine
• 3GM30F Three-Cylinder Diesel Engine
• 3HM Three-Cylinder Diesel Engine
• 3HMF Three-Cylinder Diesel Engine
• 3HM35 Three-Cylinder Diesel Engine
• 3HM35F Three-Cylinder Diesel Engine

ENGINE NOISES

Often the first evidence of an internal engine problem is a strange noise. That knocking, clicking or tapping sound never heard before may be warning of impending trouble.

While engine noises can indicate problems, they are difficult to interpret correctly; inexperienced mechanics can be seriously misled by them.

Remember that diesels are much noisier than gasoline engines and have a normal clatter at idle, especially when cold. It is necessary to become accustomed to these normal noises in order to detect possible problem-associated noises.

Professional mechanics often use a special stethoscope for isolating engine noises. The home mechanic can do nearly as well with sounding stick, which can be an ordinary piece of dowel, a length of broom handle or a section of small hose.

Place one end in contact with the area in question and the other end near the ear to hear sounds emanating from the area. There are many strange sounds coming from a normal engine. If possible, have an experienced mechanic help sort out the noises.


CLICKING OR TAPPING NOISES

Clicking or tapping noises usually come from the valve train and indicate excessive valve clearance. A sticking valve may also sound like a valve with excessive clearance. In addition, excessive wear in valve train components can cause engine noises.

FUEL TRANSFER PUMP

The engine is equipped with a fuel transfer pump (A, Figure 36) to move fuel from the fuel tank to the fuel filter and fuel injection pump. A cam lobe on the engine camshaft operates the pump diaphragm to pump the fuel. Fuel pump pressure is approximately 9.7 kPa (1.4psi).

The transfer pump output port on 1GM and 1GM10 engines is on the left side with the pump mounted on the engine. On all other engines, the output port is on the right side.

FUEL PUMP TESTING

1. Loosen the air bleed screw (Figure 38) on the fuel filter.



2. Operate the engine starter. If the fuel transfer pump is operating properly, fuel will flow from the air bleed screw hole.



3. If fuel does not flow from the air bleed screw hole, disconnect the output fuel line (B, Figure 36) from the fuel pump.



4. Operate the engine starter. If fuel does not flow from the fuel pump, replace the pump.

REMOVAL AND INSTALLATION

1. Close the fuel tank valve.



2. Disconnect the fuel lines (A, Figure 39) from the fuel transfer pump.



3. Remove the fuel pump retaining bolts (B, Figure 39), and then remove the pump.

• General information
• Troubleshooting
• Operation, lubrication, maintenance and tune-up
• Lay-up and fitting out
• Single-cylinder engines
• Multicylinder engines
• Fuel injection and governor systems
• Cooling system
• Electrical system
• Transmission - KM series
• Transmission - KBW series
• Wiring diagrams