Cooling System; Changing Coolant - Westerbeke 8.0KW - 60Hz Operator's Manual

COOLING SYSTEM
DESCRIPTION
Westerbeke marine diesel engines are designed and equipped
for fresh water cooling. Heat produced in the engine by com-
bustion 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 trans-
ferred 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 w~rds, 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 systetp.. The
fresh
water
co?lant and
raw water
circuits
are
independent of
each other. Usmg only fresh water coolant within the engine
allows the cooling water passages to stay clean and free from
harmful deposits.
FRESH WATER COOLING CIRCUIT
NOTE: Refer to
the
ENGINE COOLANT section for the rec-
ommended antifreeze and water mixture to be used as the
fresh water coolant.
F~h
water coolant .is pumped through the engine by a circu-
latmg pump, absorbmg heat from the engine. The coolant
then passes through the thermostat into the manifold, to the
heat ex:hanger
w~ere ~t
is cooled,. and returned to the engine
block Vla the suctIon SIde of the CIrculating pump.
ENGINE BLOCK COOLANT DRAIN
When the engine is started cold, external coolant flow is pre-
vented 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
A coolant recovery tank allows for engine coolant expansion
and contraction during engine operation, without any signifi-
cant loss of coolant and without introducing air into the cool-
ing system. This
tank
should be located at or above the
engine manifold level and should be easily accessible.
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 systllllJ maintenance is
critical;
a
substantial number
of
engine failures can be
traced back to cooling system Co"os/on.
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 petcock on the heat exchanger should also
be used to help drain engine coolant.
A
WARNING:
Beware of the hot engine coolant.
Wear protective gloves.
Engines & Generators
14