eroded water pump, air pocket.

just to be sure its not the head gasket, get a combustion gas test kit. you add a chemical to a sample of your coolant and if it turns blue or something then you have CO2 in your coolant which means a combustion leak into the cooling system.

I still think it's your thermostat.

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Well I'm going to try to take it to the mechanic tomorrow, should be the end of this probem. I really dont have too much time during the week to do this stuff. Although I learned a hell of alot with compression testing, changing the thermostat, and I actually want to do it myself so I can learn more. If I feel adventurous enough tomorrow I will give this combustion gas test thing a try. If not mechanic.

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Really? Why do you say so? I just replaced it...Maybe I screwed it up somewhere?

If you didn't change the cap you'll be kicking yourself in the end [that's if the mechanic is honest enough to tell you it was that simple].
I still agree with Batman tho - It still sounds like your T-stat. But just change the $5 cap just in case.

recently i had the same problem. it seems that there is so much pressure in the radiator that all my coolant goes into the over flow tank which leads to loss and overheating. does this really happen when your thermostat is stuck close?

im planning to change it with failsafe thermostat. is this a good brand and 192 degrees is ok?

This post has been edited by nics: Aug 18, 2008 - 1:58 PM

did you pull out the radiator and clean it? clogged radiators are a very common cause of overheating in traffic, but ok on the highway, assuming the fans operate ok. gets especially worse when the a/c is on.

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O.k just got the celica back and the culprit was the thermostat!!! What the hell I changed it for a brand new one! I didn't find out why though because my mechanic had to leave early, i'm gonna call him tommorrow so i can get all the details. I still cant believe that it was the thermostat, Batman you nailed it right on the head.

Thanks to everyone who helped, i learned alot.

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did you CEL went on? mine did yesterday.