COOLING
SYSTEM
HEAT
EXCHANGER
Cool
raw
water
flows
through
the
inner tubes of
the
heat
exchanger.
As
the
en~e.
coolant passes around these
tubes
!11e
heat
of the internal
engme
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
hmnful deposits
found
in
raw
water.
NOTE:
Operating in silty arul/or.tropical waters
may
require
that a heat exchanger cleaning be peeformed
more
often then
every
1000
hours.
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
thennostat to
prevent
the
.exhaust
manifold
from
over-
heating).
As
the
engine
warms
up,
the
thennostat
gradually
opens.
The
thermostat
is
accessible
and
can
be
checked,
cleaned,
or
replaced
easily.
Carry a spare thennostat
and
gasket.
If
you
suspect a
faulty
thermostat,
place it
in
a
pan
of
water
and
bring
to
a
bOil.
A
working
thermostat should
open
about
112"
Heat
Exchanger
Service
After
approximately
1000
hours
of
operation,
remove,
clean
and
pressure test
the
engine's
heat
exchanger.
(A
local
automo-
tive
radiator
shop
should
be
able to
clean
and
test
the
heat
exchanger).
ZINC
ANODES
..
NEW
THROWOUT
ZINC
ANODE
THROWOUT
CLEAN
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
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
r.esult
of
each particular installation
and vessel location, not that
of
the
engine.
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
alot
of
zinc
flakes
within
the
exchanger.
Remove
the end of the heat
exchanger
and
clean
the
inside
of
all
zinc
debris.
Al.ways
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),
0-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.
THERMOSTAT
ASSEMBLY
IW'IWESTERBEKE
.f Engines & Generators
.
-17
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