Cadillac 1994 DeVille Owners Literature page 245

You can be burned if you spill coolant on hot engine parts,
Coolant contains ethylene glycol and it will burn if the engine
parts are hot enough. Don't spill coolant on a hot engine,
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I
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1. You can remove the radiator pressure cap when the cap and upper
radiator hose are no longer hot.
0
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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