Ive got a 2001 monte. A few months back it started running hotter than usual. It doesnt overheat but my temp guage will go up between 1/2 and 3/4, it used to stay be8tween 1/4 and 3/4. As soon the temp goes past 1/2 the transmission begins shifting rough and i can smell coolant. But its not leaking.
It does this more when im at a red light or sitting with the car idling. This made me think my fans werent working. But they work fine.
Thermostat and temperature sensor were changed less than a year ago. Just did coolant flush last week.
Im stumped

 

What engine is in your car? Have you opened the radiator to ensure the radiator is full of coolant? When is the last time the cooling system has been flushed?

 

Its the 3.4L i just flushed the coolant system about a week and a half ago. And bled the system. Radiator is full.

 

A full radiator is a good sign, coolant is not leaving the system.

Did this condition start before you flushed the system? If it started after, was it right after or a few days?
I know sometimes despite the best efforts in bleeding the air, there could still be some in the system and that can account for odd behavior.

 

I agree with The Maniac. I had an Impala with that motor one time and it did the same thing. It only needed a burp Try to make sure there is no air in the system. Good luck.

 

Ya. It started doing this before I flushed the radiator. I did try to burp it a few times again and theres no air. There does seem to be too much pressure though. Almost like the thermostat is bad already.