DETROIT DIESEL 53
open when the temperature reaches 167 - 172-F. (In-
line engine) or 174 - 176 F. (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.
Check the bleed hole in the thermostat housing to be
sure it is open (Fig. 5).
Drill a 3/32" diameter hole in the thermostat housing
used on in-line industrial engines built prior to serial
(refer to Fig. 6).
This will provide a coolant drain hole for the by-pass
cavity in the housing.
2. Remove the hose connections between the
thermostat housing water outlet elbow and the radiator
or heat exchanger.
3. Loosen the bolts and remove the water outlet elbow
Refer to Fig 2
and install the thermostat(s) as
from the thermostat housing on the in-line engine
(Fig. 2). Take out the thermostat.
1. Place a new gasket on the thermostat housing
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, 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. The incom-
plete combustion of fuel due to cold operation will
result in a build-up of carbon deposits on the pistons.
rings and valves.
The operation of the therm&tat may be checked by
immersing it in a container of hot water (Fig. 4).
Place a thermometer in the container, but do not allow
it to touch the bottom. Agitate the water IO maintain
an even temperature throughout the container. As the
Method of Checking Thermostat
water is heated. the thermostat valve should begin to