FRESH
WATER
COOLING
CIRCUIT
DESCRIPTION
The fresh water cooling circuit consists
of
a circulatory belt-
driven water pump, a thermostat and thermostat housing,
. heat
exc~anger,
engine manifold, and
all
associated hoses.
.
IMPELLER
BRACKET
FRESH
WATER
PUMP
The
water
pump
is a centrifugal impeller type and is
mounted on the front upper part
of
the cylinder block. The
pump shaft is supported on maintenance-free (grease-filled)
double-row radial ball bearings.
COOLANT
TEMPERATURE
SE~
TYPICAL
THERMOSTAT
ASSEMBLY
Thermostat. A thermostat housing is located on the cylinder
head water outlet. Enclosed is a wax pellet-type thermostat.
The valve opening temperature is not affected by variations
_
of
pressure in the cooling water passages.
The water temperature switch
and
the water temperature
sender are both mounted
in
the thermostat housing. The
water temperature switch, normally open in a propUlsion
engine, when activated, will close and sound an alarm. The
water temperature switch, normally closed
in
a generator
drive engine, when activated, will open and interrupt
DC
Voltage to the fuel run solenoid and shut the drive engine
down. the water temperature sender is a variable resistor
affected by heat. Voltage from the water temperature gauge is
grounded through the sender to the block. Depending on the
resistance through the sender effected by coolant heat, the
gauge will indicate a temperature reading.
Change
of
Coolant. Over a long period
of
engine operation,
scale will be deposited and rust formation will occur in the
water jacket and heat exchanger, causing progressive deterio-
ration in cooling system efficiency. For this reason, flush the
cooling system every
500 hours
of
engine operation.
Antirust
and
Antifreeze.
To
protect the cooling system
against corrosion and freezing, always use a known brand
of
antifreeze compatible with aluminum cooling system compo-
nents. The use
of
an antifreeze mixture
of
50/50 is recom-
mended for year-round use. Use antifreeze that is compatible
with aluminum components, and never mix different brands
of
antifreeze.
Do
not
use plain water; this can be detrimental
to
the cooling system components.
NOTE:
Look for the new environmentally-friendly long lasting
antifreeze that
is
now available.
Antifreeze mixtures will protect against an unexpected freeze
and they are beneficial to the engine's cooling system. They
retard rust and add to the life
of
the circulating pump seal.
ANTIFREEZE
PROTECTION
Antifreeze
concentration
23%
35%
50%
60%
Freezing
temperature
14°F
-4°F
-40°F
(-10°C)
(-20°C) (-40°C)
COOLANT
RECOVERY
TANK
Engines & Generators
47
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