Ok so I have searched and havent really found the exact situation I'm having here... but if someone finds it feel free to post the link, that would be greatly appreciated.

First of all its an 01 Cav 2.2L...

Now here is the problem, overheats on the highway in stop and go... but I cant get it to overheat any other time...

I replaced the thermostat because all signs lead to that and I figured it was due anyways... AC Delco of coarse, but its still doing it... pressure tested with no leaks and coolant is not that old....fans come on no problem and both upper and lower rad hoses get nice and hot... plenty of heat in the car...

I'm at a loss here guys, if someone has a suggestion for me that would be great, I'm not looking to throw parts at it without trying to properly diagnose it...

Thanks a lot for the help.... its greatly appreciated!

There arent that many components to the coolant system. Other than trying a temp sensor because they are cheap, you are probably looking at replacing the water pump. If its original, the pump can have rusted away blades inside and still be pumping water but just not the volume the car needs.

Good luck

Could simply be that there is an incorrect mix of water and coolant.



My wife's 2003 Ecotec 2.2 liter Sunfire:
* 2 1/4 inch in and dual 2 inch out muffler Trans Am muffler
* 2 1/4 piping to a very long 2 1/4 inch resonator
* 2 1/4 inch catalytic converter
* an AEM true cold air intake NOPI edition
* 8 gauge ground wire kit
* Toyz front strut brace
* Russell stainless steel brake lines all around.