Maintenance: Cooling System; Figure 20: Coolant System - Westerbeke 15.0 MEG-60Hz Operator's Manual

Operator Manual for Gasoline Generators
5.3

Maintenance: Cooling System

5.3.1 Fresh Water-Cooling Circuit
CAUTION: Proper cooling system maintenance is critical. Many premature engine failures can be traced back to cooling
system corrosion.
Westerbeke marine engines are designed and equipped for fresh water (50% anti-freeze/50% distilled water)
cooling. Heat produced in the engine by combustion and friction is transferred to fresh water, which circulates
throughout the engine. This circulating fresh water cools the engine block and its internal moving parts. The
heat is transferred externally from the fresh water to sea water by means of a heat exchanger, similar in
function to an automotive radiator. Sea water flows through the tubes of the heat exchanger while freshwater
flows around the tubes, engine heat transferred to the fresh water is conducted through the tube walls to the
sea water which is then pumped into the exhaust system where it is finally discharged overboard. In other
words, the engine is cooled by fresh water, the fresh water is cooled by sea water, and the sea water carries the
transferred heat over the side through the exhaust system. The fresh water and sea water circuits are
independent of each other. Using freshwater coolant within the engine allows the cooling water passages to
stay clean and free from harmful deposits.
5.3.2 How to Drain and Refill the Coolant
CAUTION:
The engine must be allowed to cool down before attempting these procedures. Not only is the surface of
the engine hot, but coolant temperatures can exceed 190° F (87° C).
1. The engine coolant must be changed as directed in the maintenance schedule (Section 5.1)
2. Allow the engine to cool before continuing. For initial fill, skip to step 5.
3. Put a drain pan in place to capture coolant. It is recommended to use absorbent mats and cloths to capture
spillage.
4. Remove the drain plug on the heat exchanger.
5. Remove the pressure cap from the water jacketed exhaust manifold.
6. Allow coolant to drain.
7. Reinstall coolant drain plugs.
8. Premix fresh coolant and distilled water or use premixed 50/50 coolant.
9. Remove pressure cap.
10. Slowly add coolant into the pressure cap opening until coolant reaches the bottom of the pressure cap
opening.

Figure 20: Coolant System

5 Maintenance
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