Slight over heating while idling?? Do I have a problem?

Asked by Mar 23, 2015 at 08:11 AM about the 2005 Pontiac Grand Prix

Question type: Maintenance & Repair

I JUST bought a used 05 pontiac grand prix,
140k miles, 3.8 engine.  was driving it
around last night for only the second day,
and left it idling in a parking lot for about 30
minutes while the person I was with ran
into the store. I noticed that the
temperature gauge, instead of resting at its
normal operating temp which is a little
below half way, was starting to rise to be a
little tiny bit above halfway. It was not
moving fast, and was not OVER heating in
the warning area of the guage, and I did not
smell burning.   My question is,  is that
normal for the temp to fluctuate like that
when idling?  Temp went back down to
norm when I started driving.. Coolant and
oil levels are good.   Just worried because I
just bought it,  and I don't remember my
other cars doing that.

43 Answers

110,725

I would change the Anti-Freeze, flush the system with water and install a new thermostat.

3 of 3 people found this helpful.
257,485

Plus idling for 30mins isn't a good for the car or the atmosphere.

2 of 2 people found this helpful.
3,335

My 2006 Grand Prix would do that too. The fans won't automatically come on and cool the radiator when idling until the coolant gets really hot or the A/C is on. When you're driving, enough wind blows through the radiator to keep it cool and at normal operating temperature.

6 of 6 people found this helpful.
Best Answer Mark helpful
645

I think Dorian nailed it. But I would check to make certain that the fan does come on.

1 of 1 people found this helpful.

Thank you. Yes I will check to see if the fan is coming on. Dorian thanks, because that is EXACTLY what it does. I noticed for the first time Monday that it does not do it when the AC is running. And it doesn't get HOT, just warmer than I expected, when idling with no AC. So Dorian, it's not a problem, right? It's just normal for this model?

3,335

Yeah, it's normal for this model.

4,325

It is totally normal. If the fluids are at the right level I wouldn't touch a thing. Drive it and enjoy it.

135

Mine runs a little over the 1/2 mark as well when idling now. It was going almost to the red when I would idle and only when I'd idle and drop down very quickly the minute I moved the car. I changed my thermostat and that fixed everything! Thank goodness!

1 of 1 people found this helpful.

I just aquired an 02 GT. It does the exact same thing.

My 2006 was doing this too. Replaced the water pump and the radiator cap. Which looked horrible. And that fixed the problem. Plenty of videos on line. $30 and not worth spending too much time thinking about it. Just do it.

4,325

I'm guessing you mean thermostat and water pump, right? Not that anyone's watching a year old thread.

3,335

Thermostats usually fail open and cause the engine to take longer to warm up. On mine, I replaced the thermos

3,335

On mine, I replaced the thermostat and coolant temperature sensor and that didn't make any difference. I found that turning on the A/C while idling forced the radiator fan to turn on and would cool the engine back down.

1 of 1 people found this helpful.

I have a 2007 Pontiac Grand prix which starting rising to dangerous level and computer told me to turn AC off to protect engine....funny thing is I didn't have AC on and was only idling 10 min I left drive thru and temperature dropped immediately any ideas as to why????

4,325

Possibly a sensor malfunctioning or perhaps a thermostat that was stuck and them came unstuck. Check your coolant level and top it up if you haven't already. Have it scanned for trouble codes too, that will likely yield some clues. In the mean time keep an eye on the temp and see what happens. Might be a freak one time thing.

20

I just bought a 1998 Pontiac Grand Prix supercharged but the car keeps running hot I change the thermostat and water pump any ideas on why the car keeps running hot?

4,325

There is most likely air trapped in the cooling system. Use the bleeder by the thermostat to bleed it out. These systems are difficult to fill without trapping air inside. If you can't get it out have a shop do it for you. They have special equipment which they use to draw the air out as they fill it. While they're at it have them flush the system and put in new coolant.

20

I have the guy that sold me the car do it for me because his the one the rebuild the car even the engine. He did all that but my car still gets hot , at first when I started driving the car I checked the oil and it looked milky I change the oil it's been a now and the oil is good now but it still gets hot. I change the oil, water pump and the thermostat

1 of 1 people found this helpful.
20

Week

4,325

Scan it for trouble codes. If its a rebuild there may be issues with that and if everything's been apart there could be issues with a sensor or something. Are the cooling fans coming on? If nothing shows up there, and the fans are coming on when it heats up I would have the cooling system drained and refilled by a qualified shop because this still sounds like air trapped in the system. It can be really tough to get out, but you need to resolve it before you wreck your new engine.

20

I got it done the thing was that the guy that sold me the car cut the down pipe of the tip of the engine.

20

How you doing I have a question? I am having trouble with my Grand Prix it's going but at the same time it doesn't shift this morning it didn't have transmission fluid when I got off of work I put some in it but it's still giving me problems like it's not shifting right?

4,325

Have a look underneath to make sure you don't have a significant leak. Did you fill it up to the full mark on the dipstick, or just put in enough to get it moving? It's important that it be full. Sounds like you could have some transmission problems brewing. I would get it checked out by a shop and have the fluid and filter changed while you're there.

20

I had brought to autozone and they had told me the ignition coil went out. But the transmission fluid going out fast.

4,325

Well its an old car so it could easily have multiple problems. I"d try to identify the transmission problem first because if the transmission is gone it may not be worth spending money on. Even a used transmission and the labor to put it in could easily exceed the value of the car. Hopefully not, but there's no point in throwing good money after bad.

20

Thanks sorry for asking to many questions but I had my brother in law change the spark plugs but I had one broke and the only thing stuck in there is the metal one that you put first but I really don't know how to it out the easy way.

4,325

No problem. Ask as many questions as you want to. That's what we're here for. You might want to start a new thread with each one though since only those who checked out your original post will be seeing your subsequent questions. Can you not get a socket onto the remaining part of the spark plug? A few drops of penetrating oil might help. Let it sit overnight and then try again with the correct socket properly seated over the spark plug base and a good ratchet with an extension on the handle should do the job.

20

Oh ok thank you so much I bought the car the guy told me yeah the car won't have any problems 2 days later water pump went out than this problem again you know I just wanna fixed it up so later on I can sell it for more. The thing is we gonna try to take it without breaking it you know but thank you a lot

20

But the thing is we can't a socket on there because that piece of metal where you put the socket broke too that's why we tried to take it out but we just gonna let sit there for tonight and see what we can do but if you can give me any idea that would be wonderful

1 of 1 people found this helpful.
20

But the thing is we can't a socket on there because that piece of metal where you put the socket broke too that's why we tried to take it out but we just gonna let sit there for tonight and see what we can do but if you can give me any idea that would be wonderful

20

Another question whenever I turn my car on the first time it doesn't start until the third time but my car keeps idling high and it does it a lot of times.

If my 2006ponatic blow cool AC but at a high level my temp..go up what's wrong.

4,325

The air conditioner AC and the engine cooling system are two totally separate and unrelated parts of your car. You have a cooling system problem you need to address. Most likely your coolant level is low. Start by filling it up and see what happens.

Question I just got a 99 Pontiac grand am couple days ago. My fan belt went, changes the thermometer, and I was told my o2 senors needed to be changed. Any who my car was slightly going above midpoint like 2 lines, my mechanic changed it and it's still sitting one or two lines above midpoint is that normal? I'm just worried it may cause bigger problems and I just got it

4,325

I'm not sure what midpoint is, but there's probably a part of the gauge that's marked in red. As long as the temp stays fairly steady and isn't going into the red zone you're fine. If it is going up into the red zone, you likely have air trapped in the system. That needs to be bled out and the system properly filled with coolant or you will do damage to your engine.

1 of 1 people found this helpful.

The middle says 90 on temp gauge and it goes over on 3 of the tinier lines. I have always got lemons so I'm just worried I was told the o2 senors need to be changed but that was it. And okay I'll try not to worry so much about it

4,325

The computer stores information about the car and what's working and what's not working. The trouble codes can tell you a lot about what the car may or may not need to keep it running properly, If the trouble codes told your mechanic it needs an O2 sensor then have it changed and enjoy your car. Grand Ams are good cars and as long as it doesn't already have a trillion miles on it you should be able to drive it for a long time.

I have a pontiac 2004 gtp supercharged and overheating . I blown my headgaskets. but i fixed it changed my radiator and water pumped but i didnt changed my thermostat. I was driving it good but now its over heating. My radiator isnt leaking any coolant . What u think it is can anyone help

4,325

First check your coolant level to make sure its actually full. If it is there's likely air trapped in the cooling system. Use the bleeder valve near the thermostat to release it. Or have it drained and refilled by a shop. They usually have the proper vacuum tools required to draw the air out of the system as it fills.

I have a colder t-stat, cooler spark plugs, trans cooler and a computer tune and my car wont run over 160° and thats on a long trip up and down hills....my trans cooler didnt even cost very much off ebay

4,325

Why did you put in a colder thermostat? Did the computer tune call for a lower operating temperature? If not you're running your engine way too cold. Put the original thermostat back in.

I have a 04 grandprix I've changed my overflow tank which had a hole in it and its getting hot still after 2 mins of driving it could it be the thermo because my heat blows cold as well

4,325

Sounds more like not enough coolant in the system or air trapped in the system. Use the bleeder by the thermostat to release air and make sure there's enough coolant in the car. Filling it with the vehicle facing uphill sometimes helps. Getting all the air out of the system can be tricky.

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