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
HEAT
EXCHANGER
BAD
The
raw
water
pump
is a self-priming, rotary
pump
with a
CLEAN
non-ferrous housing
and
a neoprene impeller.
The
impeller
DEBRIS.
BOTH
ENDS
has
flexible
vanes
which wipe against a curved
cam
plate
CLEAN
AND
REUSE
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 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
J?resent
at
s~-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.
InspictlnglChanging
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 confOnD 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-ilter
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
PN
52650
INSPECTION:
CHECK
THE
BASE
OF
EACH
BLADE
BY
BENDING
VIGOROUSLY.
REPLACE
THE
IMPELLER
IF
THERE
ARE
ANY
CRACKS.
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
apode 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
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
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 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
exchanger.)
.
NOTE:
Operating in silty and/or tropical waters
may
require
RAI""VAT.ii'<
that a
heat
exchanger cleaning
be
performed more often than
every
1000
hours.
Engines·& Generators
16