Yanmar 1GM, Operation Manual

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3-a)
If air is being taken into the cooling water system.
3-b)
Damage of the cooling water pump.
3-c)
If dirt has plugged up the cooling water pipe or the kingston cock.
4) Charge
Make sure that the charge lamp is off. If the charge
lamp does not go off, even when the engine rpms
are raised to more than 850 charging is not taking
place because of some malfunction in the charge
system.
Consult a dealer.
5) Temperature of parts
Under full power, the surface temperature of each
engine part will be about 50-60°C, or slightly hot if
touched with the hand. If the temperature is too
high, there is some abnormality. These may include
a shortage of oil or improper alignment of the
propeller shaft. Consult your nearest dealer if the
temperature of the engine parts is too high.
6) Exhaust smoke
The emission of black exhaust smoke indicates that
the engine is being overworked. If so operated, the
life of the intake and exhaust valves, piston rings,
cylinder liners, and fuel injection valve will be
shortened.
1. C.W. Temp
2. Charge
3. L.O. Press
7) Water/oil leaks
Check for any water or oil leaks, gas leakage, loose bolts, abnormal sounds, excessive
generation of heat, and vibration. If there is anything wrong, consult your nearest Yanmar
dealer.
8) Engine resonance
A sudden, large vibration of the vessel may be caused when the vibrations (resonance) of the
engine and the vibrations of the hull occur at the same time.
When this happens you should either increase or decrease engine speed.
9) Clutch operation
Clutch operation must be performed at a low speed of less than 900 rpm.