Ok so the other day my car overheats, no hot air from heater, bottom radiator hose cool, top hot and hard. Thermostat right? Well I changed it with a failsafe one that locks open if it goes bad. Put it in started car, topped everything off. was still blowing cool for a few. turned it off, let it cool, topped it off again. next day I was driving around all day with heat at normal temp. Then all of a sudden the temp goes way up, not to the red but pretty damn high(fan is on). Heat is still working so I know its not the Tstat. after a few it drops to normal. runs normal for a few then jumps back up till I got home. what could be wrong? please help me out.....


now today its overheating still, hoses are hard, and I get no heat. Well I had heat for a few minutes then nothing.

 

Might still be air in the cooling system,but sounds more like head gasket.Most repair shops can do a quick test for hydrocarbons in the coolant.
Glenn

 

Oil in water?
Water in oil?
Have you flushed your cooling system lately? How old is your water pump?

 

no oil in water. I'll check for water in the oil. its not burning coolant. the engine is out of a 94. I'm guessing the waterpump is the same. engine has roughly 90,000. head gasket wouldn't explain the fluctuations in heater temp.......