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COOLING SYSTEM
THERMOSTAT
A thermostat controls the coolant temperature as the coolant
conQ.nuously flows through the closed cooling circuit. When
the engine is first started the closed thermostat prevents
coolant from flowing (some coolant is by-passed around the
thetmostat
to
prevent the exhaust manifold from over-
heating). As the engine warms up, the thermostat gradually
opens. The thermostat is accessible and can be checked,
cleaned, or replaced easily. Carry a spare thermostat and
gll$ket.
If you suspect a faulty thermostat, place it in a pari. of water and
bring to a boil. A working thermostat should open about 1/2"
MANIFOLD
PRESSURE CAP
HEAT EXCHANGER
TO COOLANT
RfCOVERY TANK
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 though 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 automo-
tive radiator shop should be able to clean and test the heat
exchanger).
WARNING: DO NOT
ALLOW WATER TO SPILL
INTO THE GENERATOR
HOUSING ... COVER
'fH£
AIR FAN INLET
WITH FOIL WHEN
REMOVING THE END
CAP.
END GASKET
CLEAN OUT DEBRIS
ZINC ANODE
DO NOT USE SEALANT
NOTE:
Operating in silty antJ/or tropical waters
may
require
that a heat exchanger cleaning be performed TfK!re often then
every 1000 hours.
ZINC ANODE
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 con-
dition of the zinc anode should be checked monthly and the
anode cleaned or replaced, as required. Spare anodes should
be carried onboard.
NOTE:
Electrolysis is the result of each particular installation
and
vessel location, not that of the engine.
If the zinc anodes need replacement, hold the hex boss into
which the zinc anode 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 alot of 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
en~e
model's heat exchanger end gasket part
number), 0-ring and cover, and install a new zinc
~ode.
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.
ZINC ANODES
NEW
THROW OUT
THROW OUT
CLEAN AND
REUSE
Engines
&
(lenerators
13
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