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