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COOLING SYSTEM
THERMOSTAT
A thennostat, located in the coolant filler cap housing -
(illustrated below), controls the coolant's temperature by
allowing more or less coolant through it to the engine's heat
exchanger. When the engine is first started, the closed
thennostat prevents coolant from flowing through it to the
heat exchanger. Some coolant is by-passed via a by-pass
hose on the sump plate to the exchanger. This provides for
coolant circulation in the engine and for coolant temperature
rise. As the coolant wanns up, the thennostat gains control
of the engine operating temperature by allowing more or less
coolant flow to the exchanger. The thennostat is accessible
and can be replaced easily. Carry a spare thennostat and
housing gasket.
Replacing the Thermostat
Remove the cap screws and disasseinble the thennostat
housing as shown. When installing the new thennostat and
gasket, apply a thin coat of sealant on both sides of the -
gasket before pressing it into place.
Run the engine and check for nonnal temperatures and that
there are no leaks around the thennostat housing/gasket.
~
~~".v. '~
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THERMOSTAT
#048157
,GASKET
ADD SEALANT . -
AT ASSEMBLY
#048150
THERMOSTAT
ASSEMBLY
HEAT EXCHANGER
/TOCOOLANT
l'RECOVER
::.JANK
...
(":
Cool raw water flows through the inner tubes of the heat
exchanger. As the engine coolant passes around these tubes,
the heat of the internal engine is conducted to the raw water
which is then pumped into the exhaust system and
discharged. The engine coolant (now cooled) flows back
through the engine and the circuit repeats itself.
The engine coolant and raw water are independent of each
other; this keeps the engine's water passages clean from the
harmful deposits found in raw water.
Heat Exchanger Service
After approximately 1000 hours of operation, remove, clean
and pressure test the engine's heat exchanger. (A local
automotive radiator shop should be able to clean and test the
heat exchanger.)
NOTE:
Operating in silty and/or tropical waters may require
that a heat exchanger cleaning be performedmore often than
ZINC ANO'DE
TO WATER COOLED
EXHAUST
~::k-----'-
COOLANT DRAIN
~t::J1'(------RAW
WATER DRAIN
A zinc anode, or pencil, is located in the raw water cooling
circuit within the heat exchanger. The purpose of the zinc
anode is to sacrifice itself to electrolysis action taking place
in the raw water cooling circuit, thereby reducing the effects
of electrolysis on other components of the system. The
condition of the zinc anode should be checlq!d monthly and
the anode cleaned or replaced as required. Spare anodes
should be carried on board.
NOTE:
Electrolysis is the result of each particular installation
and vessel location; not that of the engine.
NEW
REPLACE
CLEAN & REUSE
If the zinc pencil needs replacement, hold the hex boss into
which the zinc pencil is threaded with a wrench while
loosening the anode with another wrench. This prevents the
hex boss from possibly tearing off the exchanger shell. After
removing the zinc, note the condition of it. If the zinc is in
poor condition, there are probably zinc flakes within the
exchanger. Remove the end of the heat exchanger and clean
the inside of all zinc debris. Always have a spare heat
exchanger end gasket in case the present one becomes
damaged when removing the end cover. Replace the gasket
(refer to your engine model's heat exchanger end gasket part
number), o-ring, cover, and install a new zinc anode.
NOTE:
The threads of the zinc anodes are pipe threads and do
not require sealant. Sealant should not be used as it may
insulate the zinc from the metal of the heat exchanger
housing preventing electrolysis action on the zinc.
every 1000 hours.
~
WESTERBEKE
Engines & Generators
17
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