Engine Coolant; Changing The Coolant; Thermostat - Westerbeke 55A FOUR Operator's Manual

ENGINE COOLANT
CHANGING THE COOLANT
The engine's coolant must be changed every eight to
twelve months depending on the engine's use. If the
coolant is allowed to become contaminated, it can lead
to overheating problems.
A coolant recovery tank allows for engine coolant expan-
sion and contraction during engine operation, without any sig-
nificant loss of coolant and without introducing air into the
cooling system. This tank should be located at or above the
engine manifold level, and be easily accessible.
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COOLANT
RECOVERY
TANK CAP
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COOLANT
RECOVERY
TANK
COOLANT EXPANSION
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. See the Parts Identification photos in this man-
ual for locations.
NOTE:
The petcock on the heat exchanger can also be
used to drain engine coolant.
A
WARNING: Beware of the hot engine coolant.
Wear protective gloves.
TO REFILL WITH COOLANT
With the enginge running in idle, slowly pour clean
premixed coolant into the manifold.
NOTE:
Open the air bleed petcock on the heat exchanger
to help remove air from the system. When a steady flow
of coolant appears at the drain plug opening, close the
water drain plug and continue to fill the system until the
manifold remains full. Close the petcock on the heat
exchanger when antifreeze flows from it.
Start the engine and bring it to operating temperature.
Monitor the coolant in the manifold and add as needed.
Fill the manifold to the filler neck and install the pressure
cap.
Remove the cap on the coolant recovery tank, fill with
coolant 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.
NOTE:
Periodically check the condition of the pressure cap.
Ensure that the upper and lower rubber seals are in good
condition and check that the vacuum valve opens and
closes tightly. Carry a spare cap.
THERMOSTAT
A thermostat, located near the manifold at the front of the
engine, controls the coolant temperature as it contin-
uously flows through the closed cooling circuit. When
the engine is first started the closed thermostat prevents
coolant from flowing (some coolant is by-passed through
a hole in the thermostat to prevent the exhaust manifold
from overheating). As the engine warms up the thermo-
stat gradually opens. The thermostat is accessible and can
be checked, cleaned, or replaced easily. Carry a spare
thermostat and gasket.
THERMOSTAT
WATER
TEMPERATURE
ALARM
WATER
TEMPERATURE
SENDER
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Engines & GeneratDrs
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