Raw Water Cooling Circuit; Heat Exchanger; Raw Water Pump - Westerbeke 29.0 EGED 60Hz Operator's Manual

COOLING SYSTEM.
RAW WATER COOUNG CIRCUIT·
The raw water flow is created by a positive displacement
impeller pump. This pump draws water directly from the
ocean, lake, or river through a hose to the water strainer. The .
raw water passes from the strainer through the heat
exchanger (through the beat exchanger tubes) where it cools
the engine ·circulating fresh water coolant. The raw water is
then discharged into the water injected exhaust elbow, mix-
ing with and cooling the exhaust gasses. This mixture of
exhaust gas and raw water is pushed overboard.
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 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 as water acts as a
lubricant for the impe1ler. 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.
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NOTE:
Should a failure occur with
the
pumps internal parts
(seals and bearings), it may be more cost efficient to
purchase a new pump and rebuild the original pump as
aspare. ·
·Inspecting/Changing the Raw Water Pump Impeller
Close the raw water intake valve. Remove the pump cover
and, with the proper size impeller tool, carefully pry the
impeller out of the pump (the impeller can be pried out using
1\
pair of screwdrivers if an impeller puller is unavailable. Take
care riot to tear the impeller). Install the new. impeller and
. gasket. ·Move the blades to conform to
the
curved cam plate
and'
push the impeller into the pumps housing. When
assembling, 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 w.ater
flow indicates the pump has not primed itself properly.
NOTE:
Never allow the pump to run dry.
Even
a short period
of dry running may destroy the impeller.
RAW WATER PUMP
PN52650
INSPECTION: CHECK THE BASE OF
EACH BLADE BY BENOING VIGOROUSLY.
REPLACE THE IMPELLER IF THERE ARE
·ANY CRACKS.
. NEW .BAD
Heat Exchanger
PN. 052493
v.~RAW
WATER DRAIN
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. .
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CLEAN'
AND '
REUSE
ZINC ANODES
The heat exchanger is made up of a copper tube which
encloses a number of small cupro-ilickel tubes. Raw water is
pumped through these small tubes and antifreeze coolant
from the engine is circulated around the tubes. The raw water
removes heat from the antifreeze coolant.
Zinc Anode
A zinc anode, or pencil, is located in the raw water cooling
circuit within the heat exchanger. The putpose of the zinc
anode is to sacrifice itself to electrolysis action taking place
in the raw water cooling circuit, thereby reducing the effects
of electrolysis on other components of the system. The con-
dition ofthe zinc anode should be checked monthly and the
anode cleaned or replaced as required. Spare anodes should
be carried on board.
NOTE:
Electrolysis action is the result of each particular
installation and vessel location; not that of the generator.
If the zinc pencil needs replacement, hold the hex boss into
which the zinc pencil is threaded with a wrench while loos-
ening the anode with another wrench. This prevents the hex
boss from possibly tearing off the exchanger shell. Mter
removing the zinc, note the condition of it.
If the zinc is in
poor condition, there are probably a lot of zinc flakes within
. the exchanger. Remove the end of the heat exchanger and
clean the inside of all zinc debris. Always have a spare heat
exchanger end gasket in case the present one becomes dam-
aged when removing the end cover. Replace the gasket (refer
to your engine model's heat exchanger end gasket part num-
ber); a-ring, cover, and install a new zinc pencil.
Heat Exchanger Service
After approximately 1000 hours of operation, remove, clean
and presSure test the engine's heat exchanger. (A local auto-
motive radiator shop should be able to clean and test the heat
i
exchanger.)
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· . · NOTE:
Operating in sz'lty and/or tropical waters may require
,.,A,rrt:J'...;'
that a heat exchanger cleaning
be
performed more often than
every 1000 hours.
Enf1ines & Generators
16