User Manual

SENR9977 47
TestingandAdjustingSection
i01889427
Cooling System - Inspect
This engine has a pressure type cooling system. A
pressure type c
ooling system gives two advantages:
•
The pressure type cooling system can operate
safely at a hig
her temperature than the boiling
point of water at a range of atmospheric pressures.
•
Thepressuret
ype cooling system prevents
cavitation in the water pump.
Cavitation is
the sudden generation of low pressure
bubbles in liquids by mechanical forces. The
generation of an air or steam pocket is much more
difficult in
a pressure type cooling system.
Regular inspections of the cooling system should be
made in order
to identify problems before damage
can occur. Visually inspect the cooling system before
tests are made with the test equipment.
Visual Inspection Of The Coo ling
System
1. Check the co
olant level in the cooling system.
2. Look for leaks in the system.
3. Inspect the radiator for bent fins and other
restriction to the flow of air through the radiator.
4. Inspect the drive belt for the fan.
5. Inspect the
blades of the fan for damage.
6. Look for air or combustion gas in the cooling
system.
7. Inspect the radiator cap for damage. The sealing
surface m u
st be clean.
8. Look for large amounts of dirt in the radiator core.
Look for la
rge amounts of dirt on the engine.
9. Shrouds that are loose or missing cause poor air
flow for co
oling.
i01964006
Cooling System - Test
Remember that temperature and pressure work
together. When
a diagnosis is made of a cooling
system problem, temperature and pressure must
be checked. The cooling system pressure will have
an effect on th
e cooling system temperature. For
an example, refer to Illustration 53. This will show
the effect of pressure on the boiling point (steam) of
water. This w
ill also show the effect of height above
sea level.
g00286266
Illustration 53
Cooling system pressu re at spec ific altitudes and boiling points
of water
Personal injury can result from hot coolant, s team
and alkali.
At operating temperature, engine coolant is hot
and under pressure. The radiator and all lines
to heaters
or the engine contain hot coolant or
steam. Any contact can cause severe burns.
Remove fi
ller cap slowly to relieve pressure only
when engine is stopped and radiator cap is cool
enough to touch with your bare hand.
The coolant level must be to the correct level in order
to check the coolant system. The engine must be
cold and t
he engine must not be running.
After the engine is cool, loosen the pressure cap
in order t
o relieve the pressure out of the cooling
system. Then remove the pressure cap.
The leve
l of the coolant should not be more than
13 mm (0.5 inch) from the bottom of the filler pipe. If
the cooling system is equipped with a sight glass,
the cool
ant should be to the correct level in the sight
glass.