2000 Cavalier overheating constantly after motor rebuild

GS550DUDE

MEMBER
2000 CHEVROLET CAVALIER

I have a 2000 cavalier that had the top end of the motor rebuilt with all new gaskets. We had hit a deer and bent up the front end. Then rebuilt the whole car. Including the motor. But now it overheats constantly and the fan is working. It seems to suck radiator fluid down and bubbles out the radiator resivor. I have purged the system several times to eliminate air bubbles and changed the thermosat twice. It still overheats. Has a new head and gaskets so its not a gasket problem. But the funny thing is when the thermosat is out of the car it does not overheat. What could be the problem? Anyone know?

5 Replies

CHEVY22

MECHANIC
1,375 POSTS

Bubbles in the overflow indicate exhaust gas in the cooling system, as far as the thermostat, check it, boil some water, throw in a thermometer check temp and then throw in thermostat, watch it and see if it opens or not, if not replace it, and you still may have a warped head or a head gasket failure depending on what happens with the thermostat, especially since it was run hot
thanks
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Saturday, March 3rd, 2007 AT 12:54 PM

GS550DUDE

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3 POSTS

The head and gaskets are new and the top end was rebuild by a garage. They said it was a radiator circulation problem. But I perged the system. So everything has been done. What else could it be. The bubbles in the resivor are from the overheating. Any suggestions?

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Saturday, March 3rd, 2007 AT 5:52 PM

CHEVY22

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1,375 POSTS

Did you do the test on the thermostat yet?

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Saturday, March 3rd, 2007 AT 6:14 PM

GS550DUDE

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Yes I did. On 2 new thermosats and both worked at 200 degrees. But the car is still overheating. Did a compression test on all cylinders also. All test good. Also did a radiator compression test. And it doesn't loose pressure. The whole motor is new accept block and cylinders. I am a mechanic at a garage and this problem has stumped everyone I know and 4 different garages. That is why I am asking around for help.

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Saturday, March 3rd, 2007 AT 9:38 PM

CHEVY22

MECHANIC
1,375 POSTS

Cooling fans coming on, ohm ect for proper resistance and anyone ever wonder if the head gasket was placed on the wrong side blocking some of the coolant ports?It is possible to do on that eng