Water Pump, Cooling Fan, and Fan Belt

b. Cleaning and Inspection.

(b) Heat the water slowly while watching the

thermometer and thermostat. The thermostat must start

WARNING

to open before the thermometer indicates 180 F.

Replace the thermostat if it fails to open at 180F or if

starts to open before 160 F.

Clean all parts in a well-ventilated area. Avoid

(4) Inspect the water outlet elbow for cracks,

inhalation of solvent fumes and prolonged

damaged threads, and distortion; replace a damaged

exposure of skin to cleaning solvent. Wash

elbow.

exposed skin thoroughly. Dry cleaning solvent

(5)

Inspect the hoses for cracks, cuts,

(fed. Spec. P-D-680) used to clean parts is

deterioration, brittleness, and other damage; replace

potentially dangerous to personnel and property.

damaged hoses.

Do not use near open flame or excessive heat.

c. Installation. Installation of the thermostat, outlet

Flash point of solvent is 100 to 138F (38 to

elbow, hoses, and fittings is the reverse of removal.

59C.

Refer to figure 4-15. Service the coolant and engine

lubrication systems. After installation, run the engine

(1) Clean all parts by washing in warm, soapy

until it reaches operating temperature, and check for

water. Remove any greasy or gummy deposits with a

leaks. Correct any leaks noted.

cloth dampened with dry cleaning solvent (fed. Spec. P-

D-680); dry thoroughly.

4-31. Water Pump, Cooling Fan, and Fan Belt

(2) Inspect the thermostat for obvious defects,

a. Fan Belt Adjustment. The fan belt should be

including ruptured bellows and distortion. If the valve,

tensioned so that it can be deflected approximately 3/4

when cold, can be pushed off its seat with only slight

inch with thumb pressure at a point midway between

effort, the thermostat is defective and must be replaced.

pulleys at the longest belt span. Adjust belt tension as

(3) Check the thermostat operation as follows:

follows:

(a) Hang the thermostat by its frame in a

(1) Loosen the alternator strap mounting screw (5,

container of water so that it does not touch the

fig. 4-16).

container. Hang a thermometer in the container to

maintain a check of water temperature.

4-29