Installation manual

COOLING SYSTEM
RAW WATER CODLING CIRCUIT
The raw water flow is created by a positive displacement
impeller pump. This pump draws water directly from the
ocean,
lake, or river from a thru-hull opening through a hose
to the
water strainer. The raw water passes from the strainer
through
the 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
exbaust
gasses. This mixture of exbaust gas and raw water is
driven through 'the stem tube and overboard.
HEAT EXCHANGER
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 dis-
charged, 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 approxiroately 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.)
TO TRANSMISSION COOLER
COOLANT DRAIN
HEAT ExC"HANGER
OUT BOTH ENDS
TO THERMOSTAT
HOUSING
RAW WATER PUMP
The raw water pump is a self-priming, rotary pump with a
non-ferrous housing and a Neoprene iropeller. The iropeller
has fle«ible blades which wipe against a curved earn plate
within the iropeller housing, producing the pumping action.
On no account should this pump be run dry. There should
always be a spare iropeller and impeller cover gasket aboard
(an iropeller kit), Raw water pump iropeller 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 iropeller blades. See
MAINTENANCE SCHEDULE,
NOTE: Should a failure occur with the pumps intern£ll parts
(seals and bearings), it may be more cost efficient to
purchase 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, using an iropeller puller, screw drivers, or pliers,
carefully pry the iropeller out of the pump. Install the new
iropeller and gasket. Move the blades to conform to the
curved earn plate and push the iropeller into the pumps hous-
ing. When assembling, apply a thin coating of lubricant to
the impeller and gasket. Qpen the raw water intake valve.
A CAUTION: If any of the vanes have broken off the
impeller, they must be found to prevent blockage in the
cooling circuit. They often can be found in the heat
exchanger.
IMPELLER SCREW
FITS INTO THE SLOT
IN THE SHAFT
TO IVlMI'VlrVlev
RAW WATER PUMP
EngInes' & Generators PART NO, 11361
18