Westerbeke 4.5 BCG - Raw Water Intake Strainer; Raw Water Pump

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·.