Cooling System; Changing Coolant - Westerbeke W35B Operator's Manual

CODLING 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 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
cool~nt
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 COOLING CIRGUIT
NOTE: Refer to the ENGINE COOLANT section for the rec-
ommended antifreeze and water mixture to be used as the
fresh water coolant.
Fresh water coolant is pumped through the engine by a circu-
lating pump, absorbing heat from the engine. The coolant
then passes through the thermostat into the manifold, to the
heat exchahger 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 pre-
vented by the closed thermostat (although some coolant flow
is bypassed around the thermostat to prevent tl:ie 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~
coolant is allowed
to
become contaminated,
it
can lead to overheating problems.
.A
GAUlflON:
Proper cooling system maintenance is
critical; a substantial number of engine failures can be
traced back
to cooling
system
corrosion.
To drain the engine coolant, Loosen the manifold pressure cap,
and remove the coolant drain located on the engine block.
Releasing the coolant drain on the heat exchanger will also
help the coolant flow.
A
WARNING:
Beware of the hot engine coolant.
Wear protective gloves.
~
.EllGINE COOIART DRA!it
~
.
,./'~~
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ENGINE BLOCK
Engines & Generators
16