b. Cleaning and Inspection.
(b) Heat the water slowly while watching the
thermometer and thermostat. The thermostat must start
to open before the thermometer indicates 180° F.
Replace the thermostat if it fails to open at 180°F 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
exposed skin thoroughly. Dry cleaning solvent
Inspect the hoses for cracks, cuts,
(fed. Spec. P-D-680) used to clean parts is
potentially dangerous to personnel and property.
Do not use near open flame or excessive heat.
c. Installation. Installation of the thermostat, outlet
Flash point of solvent is 100° to 138°F (38° to
elbow, hoses, and fittings is the reverse of removal.
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:
(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
container. Hang a thermometer in the container to
maintain a check of water temperature.