Cooling Water - Yanmar 2 QM 20 Operation Manual

Handling Precautions
Handling the fresh water cooling system of the above engines will be described here.
1) Fresh water tank capacity
Model
2 QM 20 F
2 QM 20 Y
3 QM 30 F
3 QM 30 Y
Remove the cap from the fresh water cooler, and check the water level.
If the water level is below the top of the cooling pipe, add clean soft water up
to the iron plate at the bottom of the filter.
If water is added up to the mouth of the fresh water tank, about 50 cc of water
will overflow from the filter immediately after the engine is started.
This is normal, and is caused by the increase in the volume of the water as its
temperature rises.
If the water filter cap is removed after the engine has been stopped and allowed
to cool, the water level will be 2 - 3 cm from the top of the filter.
This is also normal, and is caused by the overflow of the unnecessary water as the
temperature of the water rises.
2) Cooling water (fresh water)
Use clean soft water as the cooling water. Hard water will cause calcium build up,
poor heat transmission and a drop in the cooling affect; resulting in overheating.
3) Rust inhibitor
When the fresh water is changed, a rust inhibitor must be added to the new
water to prevent rusting.
4) Antifreeze
Use permanent type antifreeze in the winter. Freezing of fresh water will
damage the heat exchanger, cylinder head and water jacket.
Capacity
6.0 liters
6.9 liters
21.