Chevrolet Express 2007 Owner's Manual page 321

1. You can remove the radiator pressure cap
when the cooling system, including the radiator
pressure cap and upper radiator hose, is no
longer hot. Turn the pressure cap slowly
counterclockwise until it first stops. Do not
press down while turning the pressure cap.
If you hear a hiss, wait for that to stop.
A hiss means there is still some pressure left.
2. Then keep turning the pressure cap, but
now push down as you turn it. Remove
the pressure cap.
3. Fill the radiator with the proper DEX-COOL
coolant mixture, up to the base of the filler
neck. See Engine Coolant on page 312
for more information about the proper
coolant mixture.
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