COOLING
SYSTEM
THERMOSTAT
A thermostat, located
in
the
coolant
filler
cap
housing ·
(illustrated below), controls
the
coolant's
temperature
by
allowing
more
or
less
coolant
through
it
to
the
engine's heat
exchanger.
When
the
engine
is
first
started,
the
closed
thermostat prevents coolant from
flowing
through
it
to the
heat
exchanger.
Some coolant
is
by-passed
via
a
by-pass
hose
on
the
sump plate
to
the
exchanger.
This
provides
for
coolant circulation in
the
engine
and
for coolant
temperature
rise.
As
the
coolant
warms
up,
the
thermostat
gains
control
of the engine operating temperature
by
allowing
more
or
less
coolant
flow
to
the
exchanger.
The thermostat
is
accessible
and
can
be
replaced
easily.
Carry
a spare thermostat
and
housing 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·
gasket before pressing it
into
place.
Run
the
engine
and
check
for
normal
temperatures
and
that
~
oround
!he thennostat
housing/gosket.
~y~
THERMOSTAT
#048157
.
GASKET
ADD
SEALANT
AT
ASSEMBLY
#048150
THERMOSTAT
ASSEMBLY
HEAT
EXCHANGER
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
through
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
automotive 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
ZINC
ANODE
TO
WATER
COOLED
EXHAUST
~A.~---____,
COOLANT
DRAIN
b~::J.1'-'E:-----RAW
WATER
DRAIN
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
check!!d
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.
ZINC
ANODES
PN
011885
I
l
I
.
'
.
.
NEW
REPLACE
CLEAN
&
REUSE
If
the
zinc
pencil needs replacement,
hold
the
hex
boss
into
which
the
zinc pencil 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
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, 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.
every 1000
hours.
-.yo
WESTERBEKE
Engines & Generators
17
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