1997 Chevrolet Lumina • 111,000 miles

About 5 days ago I noticed my temperature gage almost reach the red zone and it was only blowing cold air. It continued to do this every time I drove. We replaced the thermostat, but nothing has changed. We were told it was probably just an air bubble. So for the past 3 days we have been unscrewing the screw by the thermostat to let the air out, because only antifreeze should be coming out. Today when we went to let some air out there was ALOT of air and smoke. We realized that the antifreeze was WELL above normal levels. Now what?
December 7, 2012.

When the engine is cold, remove the radiator cap and start the engine. If coolant shoots out, you may have a bad head gasket allowing air to enter the system.