TESTING AND ADJUSTING
This engine has a pressure type cooling system.
system problem, temperature and pressure must both be
A pressure type cooling system gives two advantages.
checked. Cooling system pressure will have an effect on
The first advantage is that the cooling system can have
cooling system temperatures. For an example, look at
safe operation at a temperature that is higher than the
the chart to see the effect of pressure and height above
normal boiling (steam) point of water. The second
sea level on the boiling (steam) point of water.
advantage is that this type system prevents cavitation
(low pressure bubbles suddenly made in liquids by
mechanical forces) in the water pump. With this type
system, it is more difficult for an air or steam pocket to
be made in the cooling system.
VISUAL INSPECTION OF THE COOLING SYSTEM
The cause for increased engine temperature is
generally because regular inspections of the cooling
system were not made. Make a visual inspection of the
cooling system before a test is made with test
Tests Tools for Cooling System
DO NOT loosen the filler cap or pressure cap on a
hot engine. Steam or hot coolant can cause severe
8T470 Thermistor Thermometer Group.
9S7373 Air Meter Group.
6V3121 Multitach Group.
9S8140 Cooling System Pressurizing Pump
After the engine is cool, loosen the pressure cap
and turn it to the first stop to let pressure out of
the cooling system. Then remove the pressure
Check coolant level in the cooling system.
Work carefully around an engine that is running.
Engine parts that are hot, or parts that are moving,
Look for leaks in the system.
can cause personal injury.
Look for bent radiator fins. Be sure that air flow
through the radiator does not have a restriction.
Inspect the drive belts for the fan.
Check for damage to the fan blades.
Look for air or combustion gas in the cooling
Inspect the filler cap and the surface that seals
the cap. This surface must be clean and the
seal must not be damaged.
TESTING THE COOLING SYSTEM
8T470 THERMISTOR THERMOMETER GROUP
Remember that temperature and pressure work
together. When a diagnosis is made of a cooling