TRUCK SERVICE MANUAL
Fig. 2 Coolant System Reservoir Installation
Fig. 3 System Warming Up
Fig. 4: As the cooling system approaches normal
operating temperature, the vacuum valve in the radiator cap
closes, the cooling system pressure rises to pressure controlled
by the cap pressure valve setting and no further air or coolant'
escapes the cooling system.
Fig. 5: In the event the cooling system becomes
overheated to the extent that pressure rises above the
established setting (controlled by the pressure valve in the
radiator cap), excess coolant will be expelled through the
radiator overflow into the reservoir. Coolant discharged from
the radiator in excess of the reservoir capacity would overflow
from the reservoir. Under this circumstance the engine should
be shut down, allowed to cool and the cause of the overheating
Fig. 6: After the initial cooling system fill
Fig. 4 Normal Operating Condition
Fig. 5 Overheated System
and the engine and cooling system have been operated to
normal temperature and the engine is then shut off, the system
in cooling down will draw coolant from the reservoir to replace
air expelled from the system during the warm-up period. As the
warm-up and cool-down cycle is repeated during operation of
the vehicle, air accumulated in the system will gradually be
expelled until a maximum fill condition is reached in the cooling
system. The coolant level in the reservoir will rise and fall
between the "ADD" and "FULL" lines.
NOTE: Any make-up coolant is to be added to the reservoir,
since the radiator cap should not normally be removed.
CTS-2019P Page 6
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