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COOLING SYSTEM
~
RAW WATER INTAKE STRAINER
NOTE:
Always install the strainer at or below the waterline so
the strainer will always be self-priming.
A clean raw water intake strainer is a vital component of the
engine's cooling system. Include a visual inspection of this
strainer when making your periodic engine check. The water
in the glass should
be
clear.
Perform the following maintenance after every
100
hours of
operation:
1. Close the raw water seacock.
2. Remove and clean the strainer filter.
3. Clean the glass.
4. Replace the washer if necessary.
5. Reassemble and install the strainer.
6. Open the seacock.
7. Run the engine and check for leaks.
NOTE:
Also follow the above procedure after having run
hard
aground.
H the engine temperature gauge ever shows a higher than
normal reading, the cause may be that silt, leaves or grass
may have been caught up in the strainer, slowing the flow of
raw water through ti:te cooling system
9:tn .
SEAI.IIIG
WASH~
STRAINER
RAW WATER INTAKE STRAINER
OWNER INSTALLED (TYPICAL)
RAW WATER COOUNG CIRCUIT
The raw water flow is created by a positive displacement
impeller pump.
This
pump draws water directly from the raw
water source (ocean, lake, or river) through a hose to the
water strainer. The raw water passes from the strainer
through the raw water pump to the heat exchanger (through
the heat exchanger
tubes)
where it cools the engine's
circulating fresh water coolant. The raw water is then
discharged into the water-injected exhaust elbow, mixing
with and cooling the exhaust gases. This
mixture
of exhaust
gas and raw water is discharged overboard by the engine's
exhaust gas discharge pressure.
RAW WATER PUMP
The raw water pump is a self-priming, rotary pump with a
non-ferrous housing and a Neoprene impeller. The impeller
has flexible blades which wipe against a curved cam plate
within the impeller housing, producing the pumping action.
On no account should this pump be run
dry.
There should
always be a spare impeller and impeller cover gasket aboard
(an impeller kit). Raw water pump impeller failures occur
when lubricant (raw water) is not present during engine
operation. Such failures are not warrantable, and operators
are cautioned to make sure raw water flow is present at start-
up. The raw water pump should
be
inspected periodically for
broken or tom impeller blades. See MAINTENANCE
SCHEDULE.
NOTE: Should a failure occur with the pump :S internal parts
(seals
and
bearings), it
may
be more cost efficient to pur-
chase a new pump
and
rebuild the original pump as a spare.
Changing the
Raw
Water Pump Impeller
Close the raw water intake valve. Remove the pump cover
and, with the aid of two small screwdrivers, carefully
pry
the
impeller out of the pump. Install the new impeller and
0-ring. Move the blades to conform to the curved cam plate
and pusb the impeller into the pumps housing. When
assembling, apply a thin coating of glycerine to the impeller
and 0-ring. Open the raw water intake valve.
RAW WATER PUMP .
. PN55624
···
-CAM PLATE
A
CAUTION:
If any of the vanes have broken off the
impeller,
they
must
be
located
to
prevent biDCkage
in .
the
cooling circuit. They often can be
found
in the heat
exchanger.
1...-IWESIERBEKE
l
Engines & Generators
14
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