When driving up the Canyon it overheats

Tiny
REDGAMER75
  • MEMBER
  • 2008 PONTIAC GRAND PRIX
  • 78,000 MILES
My 2008 pontiac grand prix is overheating when I drive up steep canyon roads & this is the only time it overheats. What may cause this.
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Saturday, August 25th, 2012 AT 5:40 PM

41 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
The radiator may be clogged, have it checked

Roy
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Saturday, August 25th, 2012 AT 5:42 PM
Tiny
REDGAMER75
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  • 2 POSTS
THanks I will def have it checked
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Saturday, August 25th, 2012 AT 5:58 PM
Tiny
BRANDONOHERN
  • MEMBER
  • 2 POSTS
  • 2005 PONTIAC GRAND PRIX
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 134,000 MILES
My 2005 3.8 v6 Grand prix overheats while idle. No problem when the care is in motion. Even if temp gets to red, I can start driving and it cools down instantly. I have not noticed any coolant leaks yet. I watched the fans and they are pulling air through the radiator, when I turn the AC on it does not seem to increase any airflow.

Does anyone have any thoughts on what it could be? Or any other troubleshooting I should do?
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
What about not moving, and just increasing the engine speed? The only thing motion is doing is intruducing ram air through the radiator. I have not seen one, but it could be a logical symptom of a water pump that is not flowing adequately. Is this happening after something else had been done to the car, or just come on all of a sudden? Is this overheat occurring with only the A/C on, or does it overheat at idle with A/C off? You say you have not noticed any coolant leaks, but make no mention of coolant level, I would have to assume it has been checked and is full, with adequate coolant concentration.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
BRANDONOHERN
  • MEMBER
  • 2 POSTS
Just idling is all I have tried. As soon as it started to heat up it, I took off down the road to cool it off. This came on all of a sudden no new work. It heats up even with AC off. The coolant level was a little low at my last oil change but nothing significant. That was before this occured.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
RLRIPPY1980
  • MEMBER
  • 3 POSTS
  • 2003 PONTIAC GRAND PRIX
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 1,250,000 MILES
I have a 2003 pontiac grand prix. It started overheating a few weeks ago. Replaced the head and intake gaskits. Ran fine for a day or two. Began running hot again. Replaced thermostat, No change. Replaced water pump. No change. Flushed radiator. No change. Will idle cool, but when you press gas or try to drive it instantly begins to heat up. Heater does not get hot even after new thermostat.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
Try raising the speed stationary, if it cools it down, it may be a water flow problem. The cooling fans should have at least two speeds, and should speed up when it starts getting hot, I am not sure of the temp breakpoint. With a temp gun, you might be able to spot cool areas of the radiator, perhaps there is restricted flow. How quickly does it overheat at an idle?
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Does the radiator fan work? What is the temp gage reading? Is there any coolant flow?
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
RLRIPPY1980
  • MEMBER
  • 3 POSTS
Yes the fan is working. The temp gauge reads cool until you rev engine or drive, then it jumps almost to red instantly. We kill it before it reaches red. Not sure of coolant flow. Motor seems to be hot while radiator and cap stay cool.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
What is engine litre size? Low speed fan comes on about 220F. Highspeed fan comes on about 230F. Hot coolant lite comes on about 260F.

Does your system use radiator cap? Can you see coolant with cap removed? Does the reservoir fill up in a hurry? Too hot is a boil over. Maybe your gage isn't reading correctly? Your radiator hoses don't get hot?

One way to check for coolant flow, is too remove the thermostat. Hook everything back up, just for testing, remove the cap, can you see or feel coolant flow?
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
MMGRANDPRIX
  • MEMBER
  • 3 POSTS
  • 2001 PONTIAC GRAND PRIX
Engine Cooling problem
2001 Pontiac Grand Prix 6 cyl Front Wheel Drive Automatic

in regards to last post about my over heating 3100 grand prix, I wanted to note that this is not a slow process. As soon as I start the car it begins to jump to overheating temps. I dont know if thats is too fast for a gasket issue or if I just missed a step in all the installs. Thank you
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Not sure what the full story is but if the gauge goes to HOT almost instantly than the engine is not actually overheating, it will take a few minutes for the engine to overheat, an inaccurate temp gauge is caused by a faulty engine coolant temp. (ECT) sensor most of the time.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
RLRIPPY1980
  • MEMBER
  • 3 POSTS
The engine is a 3100, 6 cylinder. The fans kick on but don't seem to help much. Once it starts getting hot all you can do is kill the engine. Have not tried to drive. It does have a radiator cap. I can see water in radiator. And no the hose on the radiator does not get hot. Niether does cap. Just the motor. LIke there is no coolant or water flow. Will try what you suggested, maybe we bought a bad thermostat. Could it be a sensor, aking it run hot.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
MMGRANDPRIX
  • MEMBER
  • 3 POSTS
You say it might be the temp sensor wiring or sensor its self. The inst. Cluster in the vehicle also shows a full tank of gas all the time. When I put the key on acc the tack of the fuel level will quickly show the amount of gas in the vehicle. When I start the car it will shoot to full. Could the temp gauge also be screwing with me and I did this for nothing. Not for nothing, I know, I feel safer with everything being replaced in this car. Could the instrument cluster be faulty. Its not mis reading my rps or mph. ? I took the cluster out of the car and some one removed the " check engine light" bulb from out of the back of it. SOB'z. If this helps, there is a good amount of dex cool on the pump side, but theres none on the thermo side.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
If you don't have any flow, check the water pump.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
BLUELIGHTNIN6
  • MECHANIC
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Did you install a new bulb while you had cluster out? If so, does the engine light come on and did you try to pull trouble codes? That could lead straight to the culprit.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
RLSPORTSTER
  • MEMBER
  • 1 POST
  • 2000 PONTIAC GRAND PRIX
  • 6 CYL
  • 2WD
  • AUTOMATIC
3.1 engine, replaced the water pump, thermostat, still over heats, the bottom hose is cold and the top hose is hot.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
MMGRANDPRIX
  • MEMBER
  • 3 POSTS
I did put a bulb in it, and yes the light was on. I have not ran a code to it. I have now replaced the temp sensor. It runs at lower temps but not where it should. I did notice that now my cooling fans were not turning on. I checked all the relays and they were good. I pulled the fans out of the engine bay and checked with a 12 v current. They both kicked on indivisdually. The fans work when they are out but not with the cooling system.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
In degrees F, what does the temp gage show? What makes you think it is overheating? Does the coolant reservoir fill up in a hurry? For testing, leave thermostat out, hook everything up, run the engine, does it help? Can you see coolant flow in the radiator? If you have a radiator cap you should be able to see or feel coolant flow.

Maybe you have air trapped in the system causing overheat.
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Pulling the stored code(s) should pinpoint the culprit, it could be blow fuse or even the PCM at fault that is not letting the fans run
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Tuesday, September 3rd, 2019 AT 2:30 PM (Merged)

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