Cooling System; Changing Coolant - Westerbeke 3.5 SBCG Operator's Manual

COOLING SYSTEM
FRESH WATER COOLING CIRCUIT
Fresh water (antifreeze) is moved through the engine by a
belt driven circulating pump, absorbing heat from the engine.
Some of the coolant by-passes the thermostat to maintain
circulation in the engine and is drawn through the heat
exchanger. The engine operating temperature rises and the
thermostat reacts to this and starts to open allowing more
coolant to flow through the heat exchanger. The thermostat
opening will change as it gains control of the engine
operating temperature by allowing more or less coolant
flow through it.
ENGINE COOLANT
WESTERBEKE recommends a mixture of 50% antifreeze
and 50% distilled water. Distilled water is free from the
chemicals that can corrode internal engine surfaces.
The antifreeze performs a double duty. It allows the engine to
run at proper temperatures by transferring heat away from
the engine to the coolant and lubricates and protects the cook
ing circuit from rust and corrosion,. Look for a good quality
antifreeze that contains Supplemental Cooling Additives
(SCAs) that keep the antifreeze chemically balanced, crucial
to long term protection.
NOTE:
Look for the new environmentally friendly long lasting
antifreeze that is now available.
The recommended 50/50 mixture will protect the engine
against the most extreme temperature. The antifreeze miX:ture
will also retard rust within the engine and add to the life of
the circulating pump impeller and seals.
A proper 50/50 mixture as recommended will protect the
engine coolant to temperatures of- 40"F.
The coolant recovery
tank
allows for the expansion and con-
traction of the engines coolant during engine operation with-
out introducing
air
into the system. This recovery tank is
provided and must be installed oefore operating the engine.
NOTE:
This tank, with its sltort run oJ plastcc hose, is best
located at or above the level of the engine's manifold.
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.
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
heat exchanger and opehing pressure cap. Also loosen the air
bleed petcock on the top of the heat exchanger
A
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 be at 190° F.
Refilling the Coolant
After closing the engine block drain, pour clean, premixed
coolant into the manifold and when the coolant is visible in
the manifold, start the engine and nm it at slow idle. Open
the air bleed petcocks on the manifold and the thermostat
housing.
Monitor the coolant in the manifold and add as needed. Fill
the manifold to the filler neck and when the coolant flowing
from the petcock is free of air bubbles,
clo~e
the petcock and
install the pressure cap.
Remove the cap on
th~
coolant recovery tank and fill with
coolannnix to halfway between LOW and MAX and replace
the cap. Run the engine and observe the coolant expansion
flow into the recovery tank. When the petcock on the thermo-
stat housing is free of
air
bubbles, close that petcock.
After checking for leaks, stop the' generator and allow it to
cool. Coolant should draw back into the cooling system as
the engine cools down. Add coolimt to the recovery tank if
needed. Clean up any spilled coolant.
Engines & Generators
16