/""
. \
SERVICE BULLETIN
V.21
DATE:
May
5,
1980
W58
BULLETIN NUMBER:
109
MODEL:
SUBJECT:
Two
Pass
Manifold
The
W58
employs
a
two
pass manifold,
It
is
a
key
feature of a
new
cooling
system
first
appearing
on
the
W58.
The
system
is
vented
by
the pressure
cap
at
the return side of the fresh water circulating
pump,
the point of the
lowest pressure within the system.
This
has
the advantage of increasing
cooling capacity
by
preventing cavitation
at
the fresh water
pump
under
higher
temperature conditions.
This
system will ultimately
be
incorporated
on
most
models.
The
schematic
on
the overleaf
shows
the water flow. Operation of the
circuit
is
as
follows:
1.
The
thermostat
has
a
permanent
by-pass port of .06 square inches
to assure water
flow
through the manifold while the engine
is
warming
up.
Replacement
thermostats
must
have
this
permanent
by-pass port.
2.
Hot
water leaving the engine thermostat housing passes through
the inside half of the water jacketed exhaust manifold to the
heat exchanger
inlet.
3.
Water
lea~ing
the heat exchanger enters a fresh water cooled
oil
cooler,
if
used.
4.
Water
leaving the oil cooler or heat exchanger enters the outside
half
of the water jacketed manifold.
5.
The
outside half of the manifold
is
comprised
of
two
sections:
a cooling path adjacent to the exhaust passage
and
an
air
removal
path
which
allows entrained
air
to
rise
to the top of the manifold.
6.
The
pressure
cap
is
located
at
the top of the
air
removal
path.
7.
From
the manifold, coolant returns to the suction side of the
fresh water
pump.
The
system
is
designed to accept
an
optional coolant recovery tank. This
useful accessory offers several advantages, including:
PIN:
1. A
remote
fill
point for the
circuit,
in
which
case
it
should
be
located
slightly
higher than the engine's pressure cap.
24721
Continued
•••.•.
J. H. WESTERBEKE CORP.
AVON
INDUSTRIAl.
"ARIC.
AVON.
MASS.
02322·
(fl17}
588-7700
CABI.E:
WESTCOR".
AVON·TEI.EX:
82-4444
To Next Page
Loading...
