1993 Cadillac Eldorado Owner's Manual - Page 251

R - How to Add Coolant to the Radiator 1. You can remove the radiator pressure capwhen the cooling system, including the radiator pressure cap and upper radiator hose, is no longer hot. Turn the pressure cap slowly to theleft until it first stops. (Don'tt pressdown whileturning the pressure cap.) If you hear a hiss, wait for that to stop. hiss means thereis still some A pressure left. 2. Then keep turning the pressure cap, but now push down as youturn it. Remove the pressure cap. I 1 237