Cooling System - Westerbeke 80N4 Operator's Manual

COOLING SYSTEM
DESCRIPTION
Westerbeke marine diesel engines are designed and equipped
for fresh water cooling. Heat produced in the engine by
combustion 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 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.
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
A coolant recovery tank allows for engine coolant expansion
and contraction during engine operation, without any
significant loss of coolant and without introducing air into
the cooling system. This tank should be located at or above
the engine manifold level and should be easily accessible.
~
TO COOLANT RECOVERY
TANK
)I-
COOLANT EXPANSION
COOLANT RETRACTION
NOTE:
Periodically check the condition of the manifold pres-
sure cap. Ensure that the upper and lower rubber seals are ill
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 fai/ures 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.
A
WARNING:
Beware of the hot engine coolant.
Wear protective gloves.
DRAIN PLUG
DRAIN PETCOCK
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I
Engines & Generators
SOME ENGINE MODELS ARE EQUIPPED
WITH A PETCOCK THAT ALLOWS FOR
A HOSE TO BE ATTACHED
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