Changing The Raw Water Pump Impeller; Heat Exchanger; Zinc Anode; Heat Exchanger Service - Westerbeke 20.0 BEDA Operator's Manual

ENGINE COOLING CIRCUIT
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.
. RAW WATER PuMP.
A
CAUTION:
H any of the vanes
h~ve
broken off the
impeller, they must
be
found to prevent blockage in the
cooling circuit. They can often
be
found In the heat
exchanger.
HEAT EXCHANGER
The heat exchanger is a copper cylinder which encloses a
number of small copper tubes. Raw \Vater is pumped through
the small copper tubes and the freshwater coolant from the
engine is circulated around the copper tubes. The raw water
removes heat from the freshwater coolant.
HEAT EXCHANGER
[32 KW SHOWN]
NEW
Zinc Anode
CLEAN AND
REUSE
REPLACE REPLACE
' A zinc anode, or pencil, is located in the raw water cooling
circuit within the heat exchanger. The purpose of the zinc
anode is to sacrifice itself to electrolysis action taking place
in the· raw water cooling dreuit, thereby reducing the effects
of elec::trolysis on other components of the system. The con-
dition of the 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 eaciJ 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. After
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), o-ring, cover, and install a new zinc anode.
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
exchanger.)
NOTE:
Operating in silty and/or tropical waters may require
that a heat exchanger cleaning be performed more often than
every 1000 hours.
Engi(Jes & Generators
15