Raw Water Intake Strainer; Raw Water Pump - Westerbeke BTG 8.5 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.
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 sealing 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 gapge ever shows a highe~ than
normal reading, the cause may be
that
silt, leaves or grass
may have been caught up in the strainer, slowing the flo~ of
raw water through the cooling system
RAW WATER INTAKE STRAINER
TYPICAL [OWNER INSTALLED)
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
JlUr!JP_
be run
d:rJ.
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
:SO
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 raw water intake valve.
Run the engine and check for leaks around the pump. Also
check for water discharge at the stem tube. Absence of water
flow indicates the pump has not primed itself properly.
15·
A
CAUTION:
It any of the vanes have broken off the
impellei; they
must
be located to prevent blockage in
the cooling circuit. They often can be found in the heat
exchanger