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
otean,
lake,
or river
from
a thru-hull
opening
through a hose
td
the
water
strainer.
The
raw
water passes
from
the
strainer
tltrough
the pump
to
the
heat exchanger (through
the
heat
exchanger tubes) where
it
cools
the
engine's circulating
fresh
water coolant. The
raw
water
is
then
discharged
into
the
water-injected exhaust
elbow,
mixing
with,
and
cooling
the
exhaust gasses. This mixture of exhaust
gas
and
raw
water
is
ctHven
through
the
stem
tube
and
overboard.
HEAT
EXCHANGER
0001
raw
water
flows
through
the
inner
tubes
of
the
heat
exchanger.
As
the
engine coolant passes around these
tubes,
Ute
heat of
the
internal engine
is
conducted
to
the
raw
water
which
is
then
pumped
into
the
exhaust system
and
dis-
charged.
The engine coolant
(now
cooled)
flows
back
through the engine and
the
circuit
repeats
itself.
\\rOTE:
Operating
in
silty and/or tropical waters may
require
that a heat exchanger cleaning
be
peiformed
more
often
then
every 1000
hours.
~(,
•..
::JI!lllE£!:;/",,'l:ii.~=----RAW
WATER
DRAIN
HEAT
EXCHANGER
CLEAN
OUT
BOTH
ENDS
ZINC
ANODE
CLEAN
OUT
DEBRIS
NEW
REPLACE
GLEAN
AND
REUSE
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
the
system.
The
condition 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 is
the
result
of
each particular installation
and vessel location; not that
of
the
engine.
NOTE:
The
threads
of
the
Zinc
anodes
are
pipe
threads
and
do
not
require
sealant. Sealant should not
be
used as
it
may
insulate
the
zinc from
the
metal
of
the
heat exchanger
housing preventing electrolysis action
on
the
zinc.
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
fle:(cible
blades 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).
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.
The
raw
water
pump
should
be inspected
periodically for broken
or
tom impeller blades. See
MAINTENANCE
SCHEDULE.
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
a
spare.
Changing
the
Raw
Water
Pump
Impeller
Close
the
raw
water intake
valve.
Remove the
pump
cover
and,
using
an
impeller
puller,
screw drivers, or pliers,
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
pumps
hous-
ing.
When
assembling, apply a thin coating of lubricant
to
the
impeller
and
gasket.
Qpen
the
raw water intake
valve.
A
CAUTION:
If
any
of
the
vanes
have
broken
off
the
impeller,
they
must
be
found
to
prevent
blockage
in
the
cooling
circuit.
They
often
can
be
found
in
the
heat
exchanger.
INSPECTION:
CHECK
THE
BASE
OF
EACH
BLADE
BY
BENDING
VIGOROUSLY.
REPLACE
THE
IMPELLER
IF
THERE
ARE
ANY
CRACKS.
LIGHTLY
GREASE
THE
PUMP
CHAMBER,
O-RING,
AND
IMPELLER
WitH
GLYCERIN.
INSPECT
THE
O-RING
AND
IMPELLER.
REPLACE
IF
THEY
SHOW
SIGNS
OF
WEAR.
RAW
WATER
PUMP
Engines & Generators
17