Raw Water Pump; Raw Water Intake Strainer - Westerbeke 7.0 BCG Operator's Manual

COOLING SYSTEM
RAW WATER INTAKE STRAINER
NOTE:
Always install the strainer at or below the waterUne so
the strainer will always be self-priming.
A clean raw water int.alee 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.
Perfonn 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.
If 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 tQ.e cooling system
~
SEAUllG
WASH~
RAW WATER INTAKE STRAINER
OWNER INSTALLED (TYPICAL)
RAW WATER COOLING CIRCUIT
The raw water fiow 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 circulat-
ing fresh water coolant.
~.raw
water
is
then discharged
into the water-injected eifiaust elbow, mixing with and cool-
ing the exhaust gasses. 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,housjng and a Neoprene impeller. The impeller
has flexible pladeS which wipe against a curved
cam
plate
wiililii ihe @peller housing, producing the pumping action.
On no account should this
pump fJ' e
run dry.
There should
always
be
a spare impeller and impeµer cover gasket aboard
(an impeller kit}. Raw water pump impeller failures occur
when lubricant (mw 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 mw water pump should be
inspected
periodically for
broken or
tom
impeller blades. See MAINI'ENANCE
SCHEDULE.
NOTE:
Should a failure occur with the
pump~
internal parts
(seals and bearings), it
may
be more cost efficient to
pur-
chase a new pump and ntbuild
the
original pump as a spare.
Changing the Raw
Water Pump 1...,eller
Close the raw water int.alee valve. Remove the
pump
cover
and, with the aid oftwo·small screwdrivers, carefully
pry
the
impeller out of the pump. Install the new impeller and gasket.
Move the blades to confonn to the c:urved cam
plate
and
push the impeller into the pump's housing. When assem-
bling, apply a thin coating of lubricant to the impeller and
gasket. Open the ~w water int.alee valve.
IMPELLER
RAW WATER
PUMP
APPLY LUBRICANT
OR LIQUID SOAP
·AT ASSEMBLY
A
CAUTION:
If any of lhe vanes have btalceo off lhe
impeller, they
must
be located
to
prewmt
blOckage
in
the
cooling circuit. They often can
be
found
in
the
heat
exchanger.
lwlWEBTERBEKE
l
Engines & Generators
15