R.2
with the
shaft.
Take
care
that
all
the impeller blades
bend
in
the
same
direction
and
trailing.
e. Inspect the front cover for wear.
A
worn
front cover should
ulti-
mately
be
replaced.
Sometimes
it
can
be
reversed
as
an
emer-
gency
measure, but not
when
stamped
markings
would
break the
seal
between
the cover
and
the
impeller
bl
ades.
f.
Reinstall the
end
cover with a
new
gasket.
g.
Be
doubly sure to
check
quickly
for
sea water
flow
when
starting
the engine.
The
absence of
flow
indicates
that
the
pump
may
not
be
priming
itself
properly.
This
situation
must
be
investi-
gated immediately or
damage
to
the
new
impeller will
result
from
overheating.
6.
ENGINE
FRESH
WATER:
It
is
preferable to
fill
your engine
with a
50%
antifreeze-water mixture.
This precludes the necessity of drain-
ing coolant
in
the winter. Since
most
antifreezes contain preservative agents
of
one
kind
or another, rusting within
the engine
is
minimized.
Also
the
anti-
freeze mixture boils
at
a higher
tem-
perature than water, giving cooling
system
"head
room.
II
When
draining the engine,
open
the
pressure
cap
first
to
relieve the
vacuum
created
by
draining.
7.
FILLING
THE
FRESH
WATER
SYSTEM:
It
is
very important to completely
fill
the fresh water system before
starting
the engine.
It
is
normal
for
air
to
become
trapped in various passages
so
all
high points
must
be
opened
to atmos-
phere to bleed entrapped
air.
When
an
engine
is
started
after
filling
with
coolant, the system
may
look
deceptively
full
until
the thermostat opens.
At
this
time
when
water
flows
through the
exter-
al cooling
circuit
for the
first
time,
pockets of
air
can
be
exposed
and
rise
to the
fill
point.
Be
sure to
add
cool-
ant
at
this
time.
8.
THERMOSTAT:
Generally thermostats are of
two
types.
One
is
simply a
choking
device
which
opens
and
closes
as
the engine tempera-
ture
rises
and
falls.
The
second
type
has
a by-pass
mechanism.
Usually
this
is
a disc
on
the
bottom
of the thermo-
stat
which
moves
downward
to close
off
an
internal by-pass passage within the
head.
Both
types of thermostats,
from
1980
onwards,
have
two
3/16" diameter
holes
punched
through
them
to serve
as
a by-pass while the engine
is
warming
up.
This
prevents overheating in the
exhaust manifold during engine
warm-up.
These
two
holes
total
approximately
0.06 square inches of area
and
replace-
ment
thermostats
must
be
equal
in
this
design
characteristic.
When
replacing a thermostat,
be
sure
that
it
is
rotated
so
as
to not
strike
the thermostat housing, pro-
jections inside the head, temperature
senders or temperature switches
which
may
be
installed
close to the
thermostat.
A thermostat
can
be
checked
for prop-
er
operation
by
placing
it
in a
pan
of cold water
and
then raising the
temperature of the water to a
boil.
The
thermostat should
open
notice-
ably (with travel
on
the order of
1/4" - 1/2")
and
be
fully
opened
when
the water
is
boiling.
9.
ENGINE
LUBE
OIL
COOLER:
Lubricating
oil
carries
heat
away
from
the engine bearings
and
other
friction
surfaces.
The
oil
circulates
from
the
lube
oil
pump,
through the engine,
through the engine
oil
cooler,
and
back
to the
oil
pump.
The
oil
cooler
may
be
cooled
either
by
engine fresh water or
by
sea water.
10.
T~~NSMISSION
OIL
COOLER:
Certain transmissions require
oil
cool-
ing.
In
these cases, the transmission
oil
cooler
is
usually cooled
by
sea
water.
Normally
sea water enters
this
cooler
after
exiting the heat exchanger, but
not always.
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