Cadillac Repair: ENGINE KEEPS OVERHEATING, blown head gasket, radiator coolant

Question
I'VE HAD A COMPRESSION TEST FOR A BLOWN HEAD GASKET(NEGATIVE). WHY DOES IT KEEP OVERHEATING?

Answer
A compression test will NOT reveal a faulty head gasket.

Did you try replacing the thermostat ?.

remove all the spark plugs and maintain about 100 lbs of compressed air into each spark plug hole for a minute and see if the radiator coolant bubbles out air with the radiator cap off. If it does on any cylinder than you have a blown head gasket.