Pontiac 1994 Firebird Owner's Manual page 166

How to Add Coolant to the Radiator
:3.4L L32 (Code S) Engine)
I. 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 to
the left until it first stops. (Don't pres:
down while turning the pressure cap.)
If you hear a hiss, wait for that to stor
A hiss means there is still some
pressure left.
2. Then keep turning the pressure cap,
but now push down as you tum it.
Remove the pressure cap.
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