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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
!he
heat
of
the internal engrne 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.
NOTE:
Operating in silty and/or.tropical waters
may
require
that a heat exchanger cleaning be peiformed 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
thermostat 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
.~d
bring to a boil. A working thermostat should open about 1/2
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).
·~
NEW
. ZINC ANODE
ZINC ANODES
a
THROWOUT
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.
~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
lwlWESTERBEKE
I
Engines
&
Generators
17
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