Installation 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
...........
'\-
...
,
I
Engines & Generators
SOME
ENGINE
MODELS
ARE
EQUIPPED
WITH
A
PETCOCK
THAT
ALLOWS
FOR
A
HOSE
TO
BE
ATTACHED
14