Raw .Water Intake; Raw Water Pump - Westerbeke 4.5 BCG Operator's Manual

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.
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 nm hard
aground.
If the engine temperature gauge ever shows a higher than
normal reading, 1he cause may
be that
silt, leaves or grass
may have been caught up in the strainer, slowing the flow of
raw water through tl;te cooling system
~
SEAUllGWAS~
STRAINER
RAW WATER INTAKE STRAINER
OWNER INSTALLED (TYPICAL)
RAW WATER COOLING 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 circulat-
ing fresh water coolant.
Th~.
raw
water is then discharged
into the water-injected e:itfumst 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,~9usjng
and a
Neoprene
impeller. The impeller
has_ flexible b,lade8 which wipe against a curved
cam
plate
wiililit
ihe@peller housing, producing the pumping
action.
On no a.ccount should this pump ITe run
dry. There should
always
be
a spare impeller and impeµer cover gasket aboard
(an impeller
kit).
Raw water p\Jmp 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 purnP, ~
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 gasket.
Move the blades
to
conform to the curved 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
nt,W
water intake valve.
IMPELLER
RAW WATER
PUMP
APPLY LUBRICANT
OR LIQUID SOAP
AT ASSEMBLY
A
CAUTION:
ff any of the vanes have
broken
off the
impeller, they
must
be
located
to prevent
biacicage
in
the cooling circuit. They often can be found in the heat
exchanger.
lwlWESTERBEKS
) Engines & Generators
15·.