MOVED: Engine overheating, need help

[Terculees]

Hello all.
I drive a 2001 RD Tibby w/ 2.0l Beta 5-speed, naturally aspirated, no engine mods.
My car started suddenly overhearing yesterday, and I can't put my finger as to why. I checked the coolant, it's full, checked the oil, it's dirty and needs to be changed, but the level is fine. My temp needle is usually centered between the 2 tiny dots on the gauge, but now when I don't run AC, in 80 degree weather it goes up to 3/4 way up, then if I turn on the AC it goes even higher. Funny thing is, if I run AC from the start, the car will turn off the AC and not turn it back on until I "reset" it (turn engine off then on). After that it will run the AC but the motor will run hot.
If this is related, problems started right after I changed the air filter in the car. I used STP filter from Autozone, $10.95. Somehow I don't think that a change in an intake filter to a cleaner one should warrant overheating in motor. It should be noted that with the new filter the car breathes easier and accelerates better.

Any ideas? Anyone? Beuler? Beuler?

[MechaniX_034]

Chck your reserve coolant reservior. If this is empty, wait until the car is in the cold condition and inspect the radiator cap. The seals should be pliable, not rock solid. If this is so, replace the cap with a new one and refill the reservior. If the seal is fine, run the car at idle and feel both top and bottom radiator hoses; if the result is one hot and one cold, you have a dead thermostat. Replace it along with the gasket, refill the coolant. Monitor for any more temperature increases.

Good luck!

[i8acobra]

Topic moved to Maintenance and Help.

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