Chevrolet Low Cab Forward 6.7L Diesel Engine 6500XD (GMNA-Localizing-
U.S.-15749874) - 2022 - CRC - 12/2/21
204
Vehicle Care
4. Remove the sub tank pressure cap by
turning the cap slowly and allowing any
pressure to be relieved before completely
lifting the cap.
5. Add coolant with the appropriate
concentration to the top of the sub tank
opening.
If the sub tank was empty when opened,
then after adding the coolant, squeeze
the upper radiator hose several time to
remove any trapped air.
6. Install and tighten the sub tank
pressure cap.
7. Run the engine until the engine coolant
temperature rises to normal level and
idle the engine for 10 minutes.
8. Turn off the engine. Allow the engine to
cool. Remove the sub tank pressure cap
and check the coolant level. Add coolant
again, if needed.
9. Install and tighten the sub tank
pressure cap.
10. Install the surge tank cover.
Check, replenish or change the engine
coolant only after the engine has sufficiently
cooled down.
When the engine is still hot, take care to
prevent engine coolant from contact with
the exhaust manifold. Any such contact
could result in exhaust manifold damage.
If you use the proper quality engine coolant,
there is no need to add extra inhibitors or
additives which claim to improve the
system. They may be harmful to the proper
operation of the system.
Do not overfill the engine coolant
reserve tank.
If the level of engine coolant changes
rapidly, have your vehicle inspected at your
dealer.
Thermostat
The engine coolant temperature is controlled
by thermostat(s). The thermostats stop
engine coolant flow through the radiator
until a preset temperature is reached. The
thermostats are installed in the engine
coolant outlet on the engine block. The
same thermostats are used in both winter
and summer. When a replacement is
needed, genuine GM parts are
recommended.
Sub Tank Pressure Cap
The sub tank pressure cap, a 108 kPa
(15.7 psi) pressure type, must be installed
tightly, otherwise engine coolant may be
lost and damage to the engine may result
from overheating. The sub tank pressure cap
should be checked periodically for proper
operation. If a replacement is required, a
genuine GM part is recommended.
Engine Overheating
When the Engine Overheats
The engine cooling system may overheat if
the engine coolant level is too low, if there
is a sudden loss of engine coolant (such as
radiator hose failure), or if other problems
occur. It may also temporarily overheat
during severe operating conditions such as:
.
Climbing a long hill on a hot day.
.
Stopping after high-speed driving.
.
Idling for long periods in traffic.
If engine power drops and the needle on the
engine coolant temperature gauge goes up
above the upper limit of the safety zone
and enters the "H" zone, the engine is
overheating. The engine overheat warning
light will come on and the warning buzzer
will sound. Either steam or boiling engine
