Installation manual
COOLING
SYSTEM
THERMOSTAT
A
thermostat
controls
the
coolant
temperature
as
the
coolant
continuously flows
through
the
closed cooling
circuit.
When
the
engine
is
first
started
the
closed
thermostat
prevents
coolant from flowing (some coolant is by-passed around the
thermostat
to
prevent
the
exhaust
manifold
from
over-heat-
ing).
As
the
engine wanns
up.
the
thermostat
gradually
opens.
The
thermostat
is
accessible
and
can
be
checked,
cleaned,
or
replaced easily. Carry a spare thermostat and gasket.
Replacing
the
Thermostat
Remove
the
cap
screws and disassemble the thermostat
housing
as
shown.
When
installing
the
new
thermostat
and
gasket, apply a thin
coat
of
sealant
on
both sides
of
the gas-
ket
before
pressing
it
into
place. Do
not
over-tighten
the
cap
screws.
Run
the
engine and
check
for normal temperatures and that
there
are
no
leaks
at
the
thermostat
housing.
If
the zinc anodes need replacement, hold the hex boss into
which
the
zinc
anode
is
threaded
with
a
wrench
while
loosening
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
a10t
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
damaged
when
removing
the
end
cover.
Replace
the
gasket
(refer
to
your
engine model's
heat
exchanger
end
gasket
part
number),
O-ring
and
cover,
and
install
a new
zinc
anode.
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.
TO
ENGINE
BLOCK
HEAT
EXCHANGER
FROM
RAW
WATER
PUMP
HEAT
EXCliAN(iER);>
COOLANT
RECIOVEllY
ZINC
ANODE
'~~?J~--
PRESSURE
"
CAP
THERMOSTAT
ASSEMBLY
{/---G.ASKET.
APPLY
SEALANT
TO
BOTH
SIDES
CLEAN
&
REUSE
NEW
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
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 onboard.
NOTE:
Electrolysis
is
the result
of
each particular installa-
tion
and
vessel location, not that
of
the engine.
-;
...
ZINC
{
ANIOE
::.
COOLANT
DRAIN
HEAT
EXCHANGER
WATER
DRAIN
Cool
raw
water
flows
through
the
inner
tubes
of
the
heat
exchanger.
As
the
engine coolant passes
around
these
tubes
the
heat
of
the
internal
engine
is
conducted
to
the
raw
water
which is then pumped into the exhaust system and discharged.
The
engine coolant (now cooled) flows back though the
engine
and
the
circuit
repeats
itself.
The
engine coolant
and
raw
water
are
independent
of
each
other;
this
keeps
the
engine's
water
passages
clean
from
the
harmful deposits found in raw water.
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 then
every
1000 hours.
Engines
&
Generators
16