organizational maintenance of the cooling system
4-24. Thermostat Housing and Thermostat
(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
(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.
(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
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
(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.