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Raw Water Pump
The raw water pump is a self-bleeding, gear-driven, rotary pump with a non-ferrous housing and a
neoprene impeller. The impeller has flexible vanes which wipe against a curved cam plate within the
impeller housing, producing the pumping action. On no account should this pump be run dry. There
should always be a spare impeller and impeller cover gasket aboard (an impeller kit). Impeller failures
occur when lubricant (raw water) is not present. Such failures are not warrantable and the operator's are
cautioned to make sure raw water flow is present at start-up. Know your pump, know its location on the
engine and know how to change the impeller in it.
SCREWDRIVER
NEOPRENE IMPELLER
CURVED CAM
SCREWORIVER
Remove the impeller with the aid of two small screwdrivers, as illustrated, and carefully pry the impeller
out of the pump. Install the impeller by positioning the hub pin to align with the slot in the drive shaft.
Move the blades to conform to the curved cam plate and push the impeller into the pump's housing.
Water Pump Drive Belt Tension
Generator models COme equipped with belt guards that cover over the belt(s) on the front of the engine.
("OUt of sight -out of mind." The belt guard is not installed for that purpose.) Operators are advised that
the inspection, service, and maintenance spoken of below should be followed.
II
WARNING
II
Never attempt to adjust the drive belt's tension while the engine is in operation.
II
CAUTION
II
Excessive water pump drive belt tension can cause rapid wear of the belt and reduce the service
life of the fresh water pump's bearings. Excessive slack or the presence of oil on the belt can
cause belt slipping, resulting in high operating temperatures.
The water pump drive belt is properly adjusted if the belt can be deflected no less than 3/8 inch and no
more
than
112 inch (I0mm, 12mm) as the belt is depressed with the thumb at the midpoint between the
two pulleys on the longest span of the belt. A spare drive belt should be carried on board.
47
WESTERBEKE GENERATORS
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