DETROIT DIESEL 53
open when the temperature reaches 167-
174 - 176F. (V-engine). The opening
temperature is usually stamped on the thermostat. The
thermostat should be fully open at approximately 190-
Clean the thermostat seating surface in the thermostat
housing and base or the water outlet elbow
Refer to Figs. 2
-and install the thermostat(s) as
Fig. 2. - Thermostat Housing Details and
Relative Location of Parts (V-Type Engine)
2. Remove the hose connections between the
thermostat housing water outlet elbow and the radiator.
3. On the V-type engine, remove the cross-over by-
pass tube which is located between the thermostat
housings. Also, disconnect the by-pass tube between
the water pump and the thermostat housing (Fig. 2).
Remove the gaskets. Then loosen the bolts and
remove the thermostat housings from their bases.
Remove the thermostats and remove and discard the
If the action of the thermostat has become impaired due
to accumulated rust and corrosion from the engine
coolant so that it remains closed, or only partially open,
Fig 3. - Method of Checking Thermostat
thereby restricting the flow of water, overheating of the
engine will result. A thermostat which is stuck in a wide
open position may not permit the engine to reach its
normal operating temperature.
combustion of fuel due to cold operation will result in a
build-up of carbon deposits on the pistons, rings and
The operation of the thermostat may be checked by
immersing it in a container of hot water (Fig. 3). Place a
thermometer in the container. but do not allow It to
touch the bottom. Agitate the water to maintain an even
temperature throughout the container. As the water is
heated, the thermostat valve should begin to
1971 General Motors Corp.