98 sunfire 2.2 SE

Most likely you have a bad water pump or clog somewhere else in the cooling system. Other possibilities are an air bubble introduced when changing the Tstat and radiator or a Tstat that was put in backwards.

Tstat only goes in one way! I bled the system of all air and believe the waterpump to be in good shape. Im thinking the new tstat I bought (heavy duty stainless steel) is to much or is faulty. So I returned it and replaced it with the old tstat and so far it's working. When I drive on the freway or at speeds over 40 it actually goes down but when I get stuck in stop and go or at an idle it goes up but so far not reaching the yellow. Thanks for your reply.

Maybe your car has a different configuration thermostat than most but many can easily be put in backwards (upside down). The flow indicator on them should point from engine block to radiator. The temp range for your Tstat should be about 195 degrees (but ask your parts guy) and it does not matter what material it is made of as long as it functions at the desired temp. If it is in backwards, the sensor will face the wrong way and hold the unit closed, not letting coolant to flow to the radiator. The fact that your temp responds to high velocity air flow across the engine tells me the radiator is not getting a chance to cool the system as it should (Low or no flow through it). That is why I suspect the Tstat. Hope you find the problem because something is restricting the flow. Good luck.

The tstat in this car has two thin bars running across the inner housing making impossible to put it in but one way only. I test drove the car today. Went out on the freeway and reached speeds of 80, 90, and cruised around 65-70 for about 25 miles with the gauge staying relatively low. As a matter of I thought it was too low so I headed closer to home and did some stop and go driving. It wasnt til I got home and let it idle that it began to climb. After approx 3 minutes it went into the red and there was water coming from I believe the expansion tank. The lower rad hose at least was warm this time around. Not sure what to try next other than running it without the tstat and see how it performs.

Ran the car at an idle for at least 15 minutes without a tstat, with the temp gauge only rising to a normal level, about half way to yellow. Im thinking the first tstat was faulty and the original is worn. Im going to buy another tstat and try it before wasting anymore $ on antifreeze.