DETROIT DIESEL 53
Two by-pass type thermostats are used in the V-type
engine. one at each cylinder head.
The by-pass system on the V-type engine consists of a
cross-over tube connecting the two thermostat housings
and an outlet tube attached between one thermostat
housing and the water pump (Fig. 1).
At coolant temperatures below approximately 170 F.
the thermostat valve remains closed and blocks the flow
of coolant through the radiators.
During this period, the coolant circulates through the
cylinder block and head and then back to the suction
side of the pump via the by-pass tube. As the coolant
temperature rises. the thermostat valve begins to open,
restricting the by-pass system and permits the coolant to
Fig. 1. -Thermostat Housings Mounted on a 6V
circulate through the radiator, When the valve is fully
open. the by-pass system of the V-type engine is
completely blocked off and all of the coolant circulates
A properly operating thermostat is essential for efficient
through the radiator.
operation of the engine.
If the engine operating
temperature deviates from the normal range of 160F -
185F., remove and check the thermostat(s).
1. Drain the cooling system to the necessary level by
opening the drain valves.
1971 General Motors Corp
SEC. 5.2.1 Page 1