Cadillac Repair: Cadillac Overheating, degree thermostat, radiator cap

Question
hello___...  I have a '94 Cadillac that overheats everytime I drive it.  Also, the heater only blows cold air.  The car DOES overheat regardless of whether or not the heater is turned on.  I replaced the 180 degree thermostat with a 190 degree thermostat (i've heard that was a mistake.)  There is plently of coolant in the car...I've noticed that my radiator cap is stuck on the radiator, the lip has been bent.  My first plan of attack: re-replace thermostat back to 180 degrees and replace radiator cap.    What else can this poor novice check?   Thank you so much for your time!!!!

Answer
Hi Corey, Actually the Caddy should have a 195 degree stat. If it doesn't open then that would cause the engine to overheat. Make sure that the antifreeze is at the top of the radiator neck. When you are warming up the engine leave the radiator cap off. If within the first 2-3 minuits the antifreeze is being pushed out of the radiator then sounds like you may have a bad head gasket. The 4.9 liter has a tendancy to do this and may have a broken head bolt or stripped threads in the block. The northstar 4.6 liter usually doesn't have a history of gasket problems. Those are the quick checks. After that you need to find out if the cooling fans turn on and what the temps are. That will need to be done at a shop. Hope that helps. Bill