Cadillac Repair: STILL OVERHEATING!, head gasket failure, combustion chambers

Question
WE JUST REPLACED THE RADIATOR IN MY 1999 CADILLAC SLS. IT STILL IS OVERHEATING!! THE THERMOSTAT WAS ALREADY REPLACED BEFORE THIS WHAT THE HELL IS WRONG NOW??? PLEASE HELP!

Answer
Are you getting adequate coolant flow thru the radiator ?.

If so, your most likely suspect is the head gaskets which is very common whereas combustion pressure is entering into the coolant passages thus preventing the flow of coolant thru the cooling system.

Remove ALL the spark plugs and have ALL the combustion chambers (cylinders) put under constant air pressure one at a time and see if any coolant gets expelled from the radiator or bubbles appear in the radiator with the radiator cap OFF.

If you get bubbles or expulsion of coolant from the radiator this will confirm head gasket failure. chambers