COOLING SYSTEM
TESTING AND ADJUSTING
COOLING SYSTEM
system problem, temperature and pressure must both be
The cooling system is a pressure type with regulators
checked. Cooling system pressure will have an effect on
at the outlet, the cooling system is equipped with a shunt
cooling system temperatures. For an example, look at the
line.
chart to see the effect of pressure and height above sea
level on the boiling (steam) point of water.
A pressure type cooling system gives two
advantages. The first advantage is that the cooling
system can have safe operation at a temperature that is
Test Tools for Cooling System
higher than the normal boiling (steam) point of water. The
second advantage is that this type system prevents
Tools Needed: 9S9102 Thermistor Thermometer
cavitation (the sudden making of low pressure bubbles in
Group.
liquids by mechanical forces) in the water pump. With this
9S7373 Air Meter Group.
type system, it is more difficult for an air or steam pocket
1P5500 Portable Phototach Group.
to be made in the cooling system.
9S8140 Cooling System Pressurizing
Pump Group.
The cause for an engine getting too hot is generally
because regular inspections of the cooling system were
The 9S9102 Thermistor Thermometer Group is used
not made. Make a visual inspection of the cooling system
in the diagnosis of overheating (engine running too hot) or
before testing with testing equipment.
overcooling (engine runs too cool) problems. This group
can be used to check temperatures in several different
VISUAL INSPECTION OF THE COOLING SYSTEM
parts of the cooling system. The testing procedure is in
Special Instruction (GMG00450).
1. Check coolant level in the cooling system.
2. Look for leaks in the system.
3. Look for bent radiator fins. Be sure that air flow
through the radiator does not have a restriction.
4. Inspect the drive belt for the fan.
5. Check for damage to the fan blades.
6. Look for air or combustion gas in the cooling
system.
7. Inspect the pressure cap and the sealing surface
for the cap. The sealing surface must be clean.
9S9102 THERMISTOR THERMOMETER GROUP
TESTING THE COOLING SYSTEM
The 9S7373 Air Meter Group is used to check the air
flow through the radiator core. The testing procedure is in
Remember that temperature and pressure work
Special Instruction (GMG00203).
together. When making a diagnosis of a cooling
9S7373 AIR METER GROUP
74
