So I just had the heater core replaced yesterday as well as all the coolant replaced. AS soon as I drove away from the shop I noticed that it is running about 15° warmer than usual. It usually runs at about 185° getting a little warmer but coming back down (as it should). Now I notice that it's hovering around 200° and just on either side of that mark. Granted it was 90° here yesterday, but even in that heat it's been pretty good about holding around 185°. Even on my commute this morning by the time I'd ben driving for about 35 min. and the outside temp reached 79° the coolant got up to 200°. I checked this morning before I left and the radiator and overflow tank were both full.

Has anyone seen a similar trend after doing cooling system work/replacing the original coolant?

Is this something I should worry about (consistently running at 200°)?

What are the odds that the thermostat is jacked up right after doing this other work?

Thanks again!

 

Hey there-
You might have some air in the system still- also what year Monte is it? Because if it's one of the more recent ones, 185 degrees seems a little cold.. Mine for example always hovers around 195 degrees or so, and it has the stock thermostat. The engine fans don't usually kick on until the temp. reaches 210 degrees or so (A/C off). With the A/C on, the fans come on sooner.

 

The air makes sense. They did warn me about that, so I thought it's be a little low this morning. Mine is an '05. It is always right on the second line before straight up and down, which I think is 185, but now is hovering straight up an down.

 

Quick question- do you have a dash like this-


LS Version aka my dash


Or one like this-



The second one is used in the LT and SS models..

With the first one, 200-204 degrees is in the dead center. My engine was hot, and it sat for a few minutes before I restarted it and snapped the picture. I have a digital readout (aka the ScanGauge) and it said 204 degrees F. In the second one, I'm not sure where 200 degrees is, but it probably is in the center just like mine is. If that's the case, then this particular Monte is running at about 190-195 degrees.

From your description it sounds like you have the second one.

Hopefully this helps and best of luck hunting down the problem.