Specifications
COOLING
SYSTEM
DESCRIPTION
Westerbeke
marine
engines
are
designed
and
equipped
for
fresh
water cooling. Heat produced
in
the engine
by
combus-
tion
and
friction
is
transferred
to
fresh
water coolant
which
circulates throughout
the
engine.
This
circulating
fresh
water
coolant
cools
the
engine
block,
its
internal
moving
parts
and
the
engine
oil.
The
heat
is
transferred externally
from
the
fresh
water coolant
to
raw
water
by
means
of a
heat
exchanger,
similar
in
function
to
an
automotive
radiator.
Raw
water
flows
through
the
tubes
of
the
heat exchanger
while
fresh water coolant
flows
around
the
tubes; engine heat
transferred
to
the
fresh
water coolant
is
conducted
through
the
tube
walls
to
the
raw
water
which
is
then
pumped
into
the
exhaust system
where
finally
it
is
discharged
overboard.
In other
words,
the
engine
is
cooled
by
fresh
water coolant,
this
coolant is cooled
by
raw
water,
and
the
raw
water
carries
the
transferred heat overboard
through
the
exhaust
system.
The
fresh
water coolant
and
raw
water circuits
are
independent of
each
other.
Using
only
fresh
water coolant
within
the
engine
allows
the
cooling water
passages
to
stay
clean
and
free
from
harmful
deposits.
FRESH
WATER
CIRCUIT
NOTE:
Refer
to
ENGINE
COOLANT
section for
the
recom-
mended antifreeze and water mixture
to
be used
as
the
fresh
water coolant.
Fresh water coolant
is
pumped
through
the
engine
by
a
circulating
pump,
absorbing heat
from
the
engine.
The
coolant
then
passes
through
the
thermostat into
the
manifold,
to
the
heat exchanger
where
it
is
cooled
and
returned
to
the
engine
block
via
the
suction side of the circulating
pump.
When
the
engine
is
started
cold,
external coolant
flow
is
prevented
by
the closed thermostat (although
some
coolant
flow
is
bypassed
around
the
thermostat
to
prevent
the
exhaust
manifold
from
overheating).
As
the
engine
warms
up,
the
thermostat
gradually
opens,
allowing
full
flow
of
the
engine's
coolant
to
flow
unrestricted
to
the
external
portion
of
the
cooling
system.
Coolant
Recovery
Tank
The coolant recovery tank allows
for
engine coolant
expansion
and
contraction
during
engine operation, without
the
introduction of
air
into
the
cooling
system.
This
tank
should
be
located at or
above
the
engine manifold
level
and
should
be easily accessible.
NOTE:
Periodically check
the
condition
of
the manifold
pressure
cap,
its
rubber seals and
the
vacuum retum
valve.
Ensure
the
passage from
the
filler neck
to
the
recovery tank
connection
is kept
clear.
CHANGING
COOLANT
The engine's coolant
must
be
changed
according
to
the
MAINTENANCE SCHEDULE.
If
the
coolant
is
allowed
to
become
contaminated, it
can
lead to overheating
problems.
A
CAUTION:
Proper
cooling
system
maintenance
is
critical;
a
substantial
number
of
engine
failures
can
be
traced
back
to
cooling
system
corrosion.
Drain
the
engine coolant
by
loosening
the
drain
plug
on
the
engine block
and
opening
the
manifold pressure
cap.
Flush
the
system
with
fresh
water,
then
start
the
refill
process.
NOTE:
The
drain plug on
the
heat exchanger
can
also
be
used
to drain engine coolant.
A
WARNING:
Beware
of
the
hot
engine
coo/ant.
Wear
protective
gloves.
Refilling
the
Coolant
After replacing
the
engine block drain
plug,
close
the
heat
exchanger's coolant petcock. Then
run
the
engine
at
idle
and
slowly
pour clean, premixed coolant into
the
manifold.
NOTE:
Open
the
air-bleed petcock on
the
heat
exchanger.
When
a steady flow
of
coolant appears at the petcock, close
the petcock and fill
the
SY$tem
until the manifold remains full.
Monitor
the
coolant
in
the
manifold
and
add
as
needed.
Fill
the
manifold
to
the filler neck and install
the
manifold pres-
sure cap.
Remove
the
cap
on
the
coolant recovery tank
and
fill
with
coolant
mix
to
halfway between
LOW
and
MAX
and
replace
the
cap.
Run
the
engine
and
observe
the
coolant expansion
flow
into
the
recovery
tank.
After checking for leaks, stop the engine
and
allow
it
to
cool.
Coolant should draw
back
into the cooling system
as
the
engine
cools
down.
Add
coolant
to
the
recovery tank if
needed.
Clean
up
any
spilled coolant.
TO
COOLANT
RECOVERY
COOLANT
EXPANSION
PRESSURE
CAP
;/
Engines & Generators
12