Справочник Пользователя для Cadillac deville 2000

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
counterclockwise (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.

2. Then keep turning the cap, but now push down as

you turn it. Remove the pressure cap.