Thread: Normal Operating Temperature 97 Grand Prix GT or overheating?

I have a 97 Grand Prox GT with 167K on the Odometer. I had replaced the radiator about 2 years ago and a coolant elbow about 6 months ago. I have a 180 degree thermostat. I have this because I have used DHP Programmed ECM and it was programmed for that thermostat. I run premium gas because of the ECM. I believe the fans turn on at an earlier temp hence the need for the lower temp thermostat.

As of lately I have been seeing the temperature get pretty high. I would normally get to about 185 and it would stay there for the entire trip. Now a 15 minute trip to the fast food joint caused it to end up at about 195. It is about 85 degrees and really humid since it is start of summer.

My AC does not work as good as it should for some reason. I replaced the compressor with a used one so I think it just is going out too. It doesn't leak Freon because its always the same temp and it wont take anymore Freon but it wont get really cold.

The other day it got up near 200 so I turned of the AC and shortly it was down to 185 again. I am reading this with my Bluetooth OBD II And Torque Android App.

Before when I found this issue I would add some water to the overflow tank since I would see it was dry and some air got in or was low on coolant. I live in Texas so I run 30 percent coolant in my water mix. I use dexcool replacement and I just bought some water wetter type coolant and added 4 oz per gallon as per the directions.

The reason I went ahead and replaced the water in the radiator because I wanted to add that stuff to the mix to get a cooler temp. But that doesn't to seem to of helped and is about the same.

Now is this normal to get this high of a temp with a 180 thermostat? I check the coolant level and it is good and when it cools down the I take off the cap it is at the neck so its not going anywhere.

The car doesn't seem to run any different but I am really used to things being really within spec when cooling systems are working right. But I have to think if the ambient temp is high outside that it would make the car temp higher regardless of the cooling efficiently.

Let me know your thoughts

The fans are working as intended and flow is good. They came on with the engine start since the AC was on in the car when I turned it on. Flow was good too as when I placed a paper town in front it sucked it on there fine.

I am thinking it may be the AC system since it cooled down when turned off. I did not replace the dryer but did replace he orifice tube an ran a vaccum. I think I need to replace it with a working one with new dryer and orifice tube.

I also have a less efficient cat and every once in a while get a code for the efficiency. But is that normal for the car to get warmer when it is warmer outside? I didn't see any leaking at the elbows but I did replace them back with Delco plastic ones from the dealership.

I did bleed the thermostat cap and it ran never got over temp in the driveway of course with the AC running.

Ahh just saw the second post so may be normal since it is a lot hotter outside and days longer so just more heat everywhere. I may try with the AC off as long as I can stand tomorrow on the way to work to see if that makes any difference.

I was thinking of possibly going back to the OEM thermostat would that be OK with the tuned ECM? Or should go back to the stock ECM?

Alright it does sound like it is just doing what it should be and just is hotter outside. I keep reading people say it shouldn't matter, some say it does. Since it could be the AC like you said not turning freely or some worn out part making it warm up that definitely could cause the higher temps. Looks like I just need to break down and go ahead and replace those to get that working as it should and take any additional load off the system.

I do notice when I drive home from work which is around 12:00AM it stays about the same without getting higher than the 185 to maybe 190. Gonna do some logging this week so I can document this and be sure.

Thanks for all the input so far guys!

This isn't my first summer with this ECM and the lower thermostat. It has been about 2 years since those were put in. I do not remember the same thing happening last summer I believe it stayed within the temps or a little higher but I am not 100 percent.

I watched it today on the way to work around 3:30PM Daytime around 93 degrees outside. It stayed at 185 for about 15 miles then crept up to 195. I turned off the AC at that time and in about 5 min it was back down to 183. Turned it back on and in a few minutes was back up to 192. So I would say the AC has an effect on it. Though not sure why it would take some time before it starts to get hotter instead of waiting a while to do so.

The AC was putting out cool air so it appears to be functioning at least somewhat, but like before it never seemed to work as good as it should. Wonder if that alone would cause this issue?

Gonna check tonight as well when I get off work when it is cooler to see what the temps look like.

Well after work driving home it was pretty steady at 185 until about half a mile until home then it crept up to 192. Definitely more stable at night than at day.