then
fill
the
system with fresh water and run the engine again for flushing.
Before and after the use of an antifreeze,
be
sure
to
flush radiator.
3)
For engine that has rather intricate water piping for
the
equipment with
oil
cooler or for other reason, open bleeding cocks
on
cooling system, each time
cooling water
changed,
to
make sure that
the
piping
is
full
in
every part.
If
an
overheat noticed even when thermostat
is
functioning well, bleed
(~r
eliminate
air
out
of)
the
system.
4)
If
dust collected on fins, clean them by blowing compressed air or water
on
them from fan
to
recover cooling efficiency. Don't try
to
remove foreign
matters with a wire
or
the like. Such a way of cleaning often makes scratches
or
cuts
in
water pipes, hence leading
to
leakage.
5-2 Thermostat
Poor operation
of
thermostat
will
much affect the service life of
the
engine
in
the
long run.
In
case
the
engine overheats even when cooling system
is
full and fan working
well
the
probable cause
is
that
thermostat has got stuck up and remains close. If, on the
contrary, long oreration should not raise water temperature up
to
the optimum
level
(75°-85°Cl.
thermostat
is
suspected
to
remain open from puncture.
In
either case,
check it and take necessary measures.
Thermostat
is
designed
to
start
opening
at
76°C and fully open at 90°C under
atmospheric pressure. Continuous operation on cold water
will
quicken wear of
cylinder liners and rings.
5-3 Tension
of
fan belt
1)
Every 60H r of run, check
the
tension of fan belt, Optimum tension
is
such
that
a press with a thumb
at
mid-point between genera-
tor
pulley and water .pump
pulley makes it slack
about
12mm. Execessive tension
quickens wear of belt itself
and
of
water pump and
generator bearings, while
lack of tension makes it slip
and a consequential drop of
cooling efficiency
will
cause
1.
Fan
belt
2.
Generator
pulley
3.
Water
pump
4.
Adjusting
plate
5.
Lock
bolt
Fig.3-36 Checking
the
tension
of
fan belt
an overheat. Continuous slipping does it
damage, too.
2)
Inspect fan belt at times
to
see
it
is
not damaged. Keep it always free from oil,
-
49-
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