After driving @ 40 miles today...My 1993 Mercury Cougar began to Over-Heat very Rapidly. Fluids were present in all reseviors. However, I did add some Engine Coolant to it. After allowing it to cool off in Temperature, I attempted to drive it a short distance. There wasn't any evidence of any fluids leaking underneath. However, there was a very dense, white smoke that was being released from the exhaust. I am extremely puzzled on what this could be. *One other thing that I would like to mention is that the Heater also stopped functioning when the over-heating problem took place

 

hey i had the same problem and i replaced the thermostat then a little while later it happened agian so i got a thermostaat with a bypass valve so that when the car gets to hot it will pop and let the heat out of the engine and that has basically solved the problem in the winter it takes a little longer to warm up but it dosent overheat now

 

it sounds similiar to a problem i had with my 99 cougar. b/c my temperature gauge just shot up to hot all of a sudden even if you didn''t drive it too much when it happened. the guy at the shop then told me to take out the thermostat and drive it like that. if it overheats then it''s somethin else. if it doesn''t overheat then you need a thermostat with a lower degree. b/c my stock size is 92degrees but they had got me an 80degree thermostat and they had to drill a little hole on the side of it to allow more engine coolant to dflow through. so that might be your problem is that your engine coolant cant flow through the thermostat too well.