Chevrolet 1995 Tahoe Owner's Manual page 254

NOTICE:
In cold weather, water can freeze and crack the engine, radiator,
heater core and other parts. So use the recommended coolant.
1. You can 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 to the left
until it first stops. (Don't 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.
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