Installation manual
COOLING
SYSTEM
RAW
WATER
COOLING
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
heat
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
dryas water acts
as
a
lubricant
for
the
impeller.
There should
always
be
a spare
impeller
and
impeller
cover
gasket
aboard
(an
impeller
kit).
Raw
water
pump
impeller
failures
occur
when
lubricani
(raw
water)
is
not
present
during
engine
operation.
Such
failures
are
not
warrantable,
and
operators
are
cautioned
to
make
sure
raw
water
flo~
is
present
at
st~-up.
NOTE:
Should
afailure 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
a
spare.
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
a pair
of
screwdrivers if
an
impeller puller
is
unavailable.
Take
care
not
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
~ngine
and
check
for
leaks
around
the
pump.
Also
check
for
water
discharge
at
the
stem
tube.
Absence
of
w.(lter
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
BENDING
VIGOROUSLY.
REPLACE
THE
IMPELLER
IF
THERE
ARE
ANY
CRACKS,
BAD
NEW:'
BA~
Heat
Exchanger
ZINC
ANODES
The
heat
exchanger
is
a
copper
tube
which
encloses a num-
ber of
small
copper
tubes.
Raw
water
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.
Zinc
Anode
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
circuit,
thereby
reducing
the
effects
of
electrolysis
on
other
components
of
ttie
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
each particular
install~tion
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),
a-ring,
cover,
and
install
a
new
zinc
pencil.
Heat,
Exchanger
Service
After
approximately
1000
hours
of
operation,
remove, clean
and
pressiIre
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.
~
WESTERBEKE
Englnes'& Generators
16