Cooling System; Changing Coolant - Westerbeke 20.0KW SBEG Operator's Manual

COOLING SYSTEM
DESCRIPTION
Westerbeke marine engines are designed and equipped for
fresh water cooling. Heat produced in the engine by combus-
tion and friction is transferred to fresh water coolant which
circulates throughout the engine. This circulating fresh water
coolant cools the engine block, its internal moving parts and
the engine oil. The heat is transferred externally from the
fresh water coolant to raw water by means of a heat
exchanger, similar in function to an automotive radiator. Raw
water flows through the tubes of the heat exchanger while
fresh water coolant flows around the tubes; engine heat
transferred to the fresh water coolant is conducted through
the tube walls to the raw water which is then pumped into
the exhaust system where finally it is discharged overboard.
In other words, the engine is cooled by fresh water coolant,
this coolant is cooled by raw water, and the raw water carries
the transferred heat overboard through the exhaust system.
The fresh water coolant and raw water circuits are
independent of each other. Using only fresh water coolant
within the engine allows the cooling water passages to stay
clean and free from harmful deposits.
FRESH WATER CIRCUIT
NOTE:
Refer to ENGINE COOLANT section for the recom-
mended antifreeze and water mixture to be used as the fresh
water coolant.
Fresh water coolant is pumped through the engine by a
circulating pump, absorbing heat from the engine. The
coolant then passes through the thermostat into the manifold,
to
the heat exchanger where it is cooled and returned to the
engine block via the suction side of the circulating pump.
When the engine is started cold, external coolant flow is
prevented by the closed thermostat (although some coolant
flow is bypassed around the thermostat to prevent the exhaust
manifold from overheating). As the engine warms up, the
thermostat gradually opens, allowing full flow of the engine's
coolant to flow unrestricted to the external portion of the
cooling system.
Coolant Recovery Tank
The coolant recovery tank allows for engine coolant
expansion and contraction during engine operation, without
the introduction of air into the cooling system. This
tank
should be located at or above the engine manifold level and
should be easily accessible.
NOTE:
Periodically check the condition of the manifold
pressure cap, its rubber seals and the vacuum retum valve.
Ensure the passage from the filler neck to the recovery tank
connection is kept clear.
CHANGING COOLANT
The engine's coolant must be changed according to the
MAINTENANCE SCHEDULE. If the coolant is allowed to
become contaminated, it can lead to overheating problems.
A
CAUTION:
Proper cooling system maintenance is
critical;
a
substantial number of engine failures can be
traced back to cooling system corrosion.
Drain the engine coolant by loosening the drain plug on the
engine block and opening the manifold pressure cap. Flush
the system with fresh water, then start the refill process.
NOTE:
The drain plug on the heat exchanger can also be used
to drain engine coolant.
A
WARNING:
Beware of the hot engine coo/ant.
Wear protective gloves.
Refilling the Coolant
After replacing the engine block drain plug, close the heat
exchanger's coolant petcock. Then run the engine at idle and
slowly pour clean, premixed coolant into the manifold.
NOTE:
Open the air-bleed petcock on the heat exchanger.
When a steady flow of coolant appears at the petcock, close
the petcock and fill the SY$tem until the manifold remains full.
Monitor the coolant in the manifold and add as needed. Fill
the manifold to the filler neck and install the manifold pres-
sure cap.
Remove the cap on the coolant recovery tank and fill with
coolant mix to halfway between LOW and MAX and replace
the cap. Run the engine and observe the coolant expansion
flow into the recovery tank.
After checking for leaks, stop the engine and allow it to cool.
Coolant should draw back into the cooling system as the
engine cools down. Add coolant to the recovery tank if
needed. Clean up any spilled coolant.
TO COOLANT
RECOVERY
COOLANT EXPANSION
PRESSURE CAP
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Engines & Generators
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