Chevrolet/GMC 3.0L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-13336148) - 2020 - CRC - 9/5/19
Vehicle Care
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Warning
Steam and scalding liquids from a
hot cooling system are under
pressure. Turning the pressure
cap, even a little, can cause them
to come out at high speed and
you could be burned. Never turn
the cap when the cooling system,
including the pressure cap, is hot.
Wait for the cooling system and
pressure cap to cool.
If no coolant is visible in the surge
tank, add coolant as follows:
1. Remove the coolant surge tank
pressure cap when the cooling
system, including the coolant
surge tank pressure cap and
upper radiator hose, is no
longer hot.
Turn the pressure cap slowly
clockwise about one-half turn.
If a hiss is heard, wait for that
to stop. A hiss means there is
still some pressure left.
2. Keep turning the pressure cap
slowly, and remove it.
3. Slowly fill the coolant surge
tank. Do not let the coolant
level go above the indicated
mark in the tank until after the
engine comes to the operating
temperature in Step 4.
4. With the coolant surge tank
pressure cap off, start the
engine and let it run until the
engine coolant temperature
gauge indicates approximately
90 °C (195 °F).
By this time, the coolant level
inside the coolant surge tank
may be lower. If the level is
lower, slowly add more of the
proper mixture to the coolant
surge tank until it reaches the
indicated mark.
5. Replace the pressure cap and
be sure it is locked.
6. Verify coolant level after the
engine is shut off and the
coolant is cold. If necessary,
repeat Steps 1
–
6.
If the coolant level is still low after
having followed these steps twice,
have the coolant system checked by
a certified technician at the dealer
for a possible leak.
Caution
If the pressure cap is not tightly
installed, coolant loss and engine
damage may occur. Be sure the
cap is properly and tightly
secured.
Automatic Coolant Fill and Air
Removal
If equipped, this feature assists in
filling and removing air from the
cooling system after service of
components or when coolant is
added after being too low.