Cooling System

TM 9-2320-312-24-2

Testing and Adjusting Section

7. Look for air or combustion gas in the cooling

system.

Personal injury can result from hot coolant, steam

8. Inspect the filler cap, and check the surface that

and alkali.

seals the filler cap. This surface must be clean.

At operating temperature, engine coolant is hot

and under pressure. The radiator and all lines

i01849241

to heaters or the engine contain hot coolant or

Cooling System - Test

steam. Any contact can cause severe burns.

SMCS Code: 1350-040; 1350-081

Remove filler cap slowly to relieve pressure only

when engine is stopped and radiator cap is cool

This engine has a pressure type cooling system. A

enough to touch with your bare hand.

pressure type cooling system has two advantages.

The cooling system can be operated in a safe

Cooling System Conditioner contains alkali. Avoid

manner at a temperature higher than the normal

contact with skin and eyes.

boiling point (steam) of water.

The coolant level must be to the correct level in

This type of system prevents cavitation in the water

order to check the coolant system. The engine must

pump. Cavitation is the forming of low pressure

be cold and the engine must not be running.

bubbles in liquids that are caused by mechanical

forces. The formation of an air pocket or a steam

After the engine is cool, loosen the pressure cap

pocket in this type of cooling system is difficult.

in order to relieve the pressure out of the cooling

system. Then remove the pressure cap.

The level 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 coolant should be to the proper level in the

sight glass.

Test Tools For Cooling System

Table 18

Tools Needed

Part

Part Name

Quantity

g00921815

Number

Illustration 68

Boiling point of water

4C-6500

Digital Thermometer

8T-2700

Blowby/Air Flow Indicator

Remember that temperature and pressure work

together. When a diagnosis is made of a cooling

9S-8140

Pressurizing Pump

system problem, temperature and pressure must

9U-7400

Multitach Tool Group

be checked. Cooling system pressure will have an

effect on the cooling system temperature. For an

1U-6602

Photo-Tachometer

example, refer to Illustration 68. This will show the

effect of pressure on the boiling point (steam) of

1U-7297

Coolant/Battery Tester

water. This will also show the effect of height above

1U-7298

Coolant/Battery Tester

sea level.

Making contact with a running engine can cause

burns from hot parts and can cause injury from

rotating parts.

When working on an engine that is running, avoid

contact with hot parts and rotating parts.