Thermostat Housing and Thermostat

TM10-3930-242-12

organizational maintenance of the cooling system

components.

4-24. Thermostat Housing and Thermostat

a. Removal.

(1) Drain the cooling system to a level below the

thermostat housing by opening the drain valve at

the bottom of the radiator.

(2) Refer to figure 4-11 and remove the ther-

mostat housing and thermostat.

b. Cleaning and Inspection

(1) Clean the thermostat housing seat and

gasket surface.

(2) Inspect the thermostat for accumulation of

rust and corrosion.

c. Testing. Check operation of thermostat. If the

thermostat remains closed, overheating of the

engine will result. If the thermostat remains open,

the engine may not reach normal operating tem-

perature, resulting in incomplete fuel combustion

and carbon buildup. To check the operation of the

thermostat, suspend it and a thermometer in a

container of water. Do not let the thermometer of

thermostat touch the bottom or sides of the con-

tainer. Heat and agitate the water to maintain an

even temperature. As the water is heated, the

thermostat should begin to open at 160 to 170 F.

and be fully open at approximately 190 F.

d. Installation

(1) Affix a new gasket to the thermostat

Figure 4-11. Thermostat housing and thermostat, removal

housing and seat the thermostat in its housing so

and installation.

that the spring (or bellows) is down or toward the

hot water side when the unit is bolted to the cylinder

4-25. Water Pump and Pulley

head.

a. Inspection.

(2) Refer to figure 4-11 and install thermostat

(1) Check water pump for leaks, excessive end

housing and thermostat.

play, and noise. Check drive belt tension.