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Posted: 6/29/2015 7:36:24 PM EDT
Link Posted: 6/29/2015 7:39:00 PM EDT
[Last Edit: 6/29/2015 7:41:45 PM EDT by splunkinoob]
Bleed the cooling system, on those cars there is one on the front valve cover near the passenger side and one on the thermostate housing near the drivers side.

Edit - if you change the thermostat, one side of the housing is slotted to work around the exhaust cross over.
Link Posted: 6/29/2015 7:40:24 PM EDT
Link Posted: 6/29/2015 7:42:34 PM EDT
What year is it? I had this issue in a 2007 Grand Prix which was just after Pontiac acknowledged an issue with the plenum gaskets in the years preceding it. On mine, however, it turned out the water pump needed to be replaced.
Link Posted: 6/29/2015 7:42:38 PM EDT
[Last Edit: 6/29/2015 7:43:48 PM EDT by KwaiChangCaine]
I'd replace the thermostat. I had one go bad and act a little like that in a 1995 Grand Prix.
Link Posted: 6/29/2015 7:43:10 PM EDT
Does the fan work? Does it have a leak?
If coolant if full and fan works replace thermostat.
If it has leak fix leak and refill/remove air.
If fan doesnt work fix fan.
Link Posted: 6/29/2015 7:43:25 PM EDT
You should have put in a new thermostat when you flushed the system.
Link Posted: 6/29/2015 7:43:48 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Db8sGr8:
What year is it? I had this issue in a 2007 Grand Prix which was just after Pontiac acknowledged an issue with the plenum gaskets in the years preceding it. On mine, however, it turned out the water pump needed to be replaced.
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EVERY 3100 and 3400 leaks from the lower intake manifolds, who knows what design revision they're on for the gaskets.
Link Posted: 6/29/2015 7:49:01 PM EDT
[Last Edit: 6/29/2015 7:50:46 PM EDT by Silver_Surfer]
Running a higher ratio of coolant to water will reduce boil-over and might help with overheatting.

I flush mine every 30-40k
Link Posted: 6/29/2015 7:50:04 PM EDT
Link Posted: 6/29/2015 7:51:25 PM EDT
Originally Posted By medicmandan:
I've had this posted on the Grand Prix forum but they don't get the traffic we do.

2001 Pontiac Grand Prix 3.1

Noticed two weeks ago the car was inching up in temp during stop and go traffic (A good distance at 40+mph brings the temp back down.). Time for a coolant flush anyway. Give it a good hose out, don't get any gunk out of the radiator. Temps have since shot up here and now if I get in prolonged stop and go traffic the temp is pushing the red line. Last couple of days when I turn it off it is boiling into the overflow tank. Water pump was replaced three years ago, everything else is original.

Another heating/cooling issue that I had forgotten about was during the winter I was not getting hot air when on the interstate, only during stop and go driving. I had planned to swap out the thermostat but then the temp warmed up and I forgot about it.

Both fans are running when the AC is on. I'm thinking a corroded radiator that is not moving enough coolant or a thermostat that is not opening all the way. Maybe some junk built up between the radiator and condenser? Any thoughts from the pros? I am good at replacing parts but terrible at diagnosing the issues.
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It's a GM car. You're thinking too much
Link Posted: 6/29/2015 7:51:45 PM EDT
[Last Edit: 6/29/2015 7:56:37 PM EDT by Furyataurus]
8 years ago???

I'd say they are leaking again as it was a poor design.
Link Posted: 6/29/2015 7:52:01 PM EDT
Recore or new radiator.
Link Posted: 6/29/2015 7:53:20 PM EDT
Link Posted: 6/29/2015 7:55:00 PM EDT
If the heat wasn't working and now its overheating I'd lean towards the thermostat. It's a $10 part and should take less than a half hour to change. I'd start there.
Link Posted: 6/29/2015 7:57:20 PM EDT
If you have not done these yet, do them.
http://amzn.com/B000CSC5MG

The supercharged version radiator fits the 3.1 cars and has 2 rows vs 1. Put one in my 2000 GP 3.1 car, fit no problem. No more overheat problems.
http://www.ebay.com/itm/1997-99-BUICK-REGAL-97-2003-GRAND-PRIX-3-8-V6-RADIATOR-W-SUPERCHARGE-AUTO-AT-NEW-/360666986720?fits=Year%3A2001|Model%3AGrand+Prix&hash=item53f96d78e0&vxp=mtr
Link Posted: 6/29/2015 7:58:59 PM EDT
Link Posted: 6/29/2015 7:59:13 PM EDT
[Last Edit: 6/29/2015 8:04:32 PM EDT by Oakenheart]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By medicmandan:



That does not look like an exciting swap.
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By medicmandan:
Originally Posted By JohnSmith6073:
Recore or new radiator.



That does not look like an exciting swap.

It's actually not too bad, took about 2hr with my very non mechanically inclined son doing the work while I supervised from a comfy chair

The trans cooler lines are snap-in, remove the clip and they pull right out, no need to unscrew fitting. Bolt on either side of radiator, it just tilts twoard engine and lifts out of the rubber grommets on bottom.

Check the trans cooler fittings on the new rad, mine were loose, and since the lines snap in I didn't catch it before install, had to fight with a wrench to tighten them up in the car. Would have saved a mess if I'd checked them.
Link Posted: 6/29/2015 7:59:51 PM EDT
Link Posted: 6/29/2015 7:59:54 PM EDT
In the mean time dont use your AC











Link Posted: 6/29/2015 8:00:41 PM EDT
Link Posted: 6/29/2015 8:07:45 PM EDT
Your plugged heater core is telling you you're radiators plugged also
That red coolant is notorious for it .... you can blow it out of the heater core but you probably need a new radiator unless a shop will clean it for cheap.
They don't cost much if you know someone that can get the shop price at NAPA .... probably under 100.00 bucks.
Don't scrimp on this shit ... the bill for blow head gasket - cracked head - or new motor will have you wishing you didn't cheap out.
Link Posted: 6/29/2015 8:08:48 PM EDT
[Last Edit: 6/29/2015 8:33:47 PM EDT by Silver_Surfer]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By medicmandan:


It stays a little cooler with the AC on. Fans don't seem to come on unless the AC is running. I'm afraid this car is about to start nickel and diming me.
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By medicmandan:
Originally Posted By Silver_Surfer:
In the mean time dont use your AC




It stays a little cooler with the AC on. Fans don't seem to come on unless the AC is running. I'm afraid this car is about to start nickel and diming me.


Normally the opisite happens.

When was the last time the thermostat was replaced?
Link Posted: 6/29/2015 8:11:37 PM EDT
Link Posted: 6/29/2015 8:12:23 PM EDT
My son bought a 95 Grand Am 3.1 for collage back in 2005.
Bought very cheap with known Overheating issues.
Head gasket is what we figured and were right.
They were know for this in addition to the Lower Plenum on the Intake Manifolds.
However if it cools down after being driven then Radiator and Cooling fans are the most logical places to start.

One thing on the 95 I remember reading is that unlike a lot of cars a plugged heater core can cause overheating issues as well, the engine uses the heater core as a bypass as part of the cooling system.
Its kind of an unusual set up as I recall.
Simple way to check since it is summer and you don't need heat, disconnect the heater hoses and run a hose between the connections on the engine, this takes the core out of the loop.
Also if I remember correctly that engine is very sensitive to proper bleeding of the cooling system or you can have a pocket of trapped air in the core and cooling system which can also cause overheating.
There are bleeder screws 3 total if I remember on that engine.
You will want them open when adding coolant, keep adding until no more air bubbles out.

Good luck and let us know.
Link Posted: 6/29/2015 8:12:44 PM EDT
Link Posted: 6/29/2015 8:13:46 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By KwaiChangCaine:
I'd replace the thermostat. I had one go bad and act a little like that in a 1995 Grand Prix.
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Yes, start with the cheapest things first.
Link Posted: 6/29/2015 8:14:03 PM EDT
Simple and likely fixes first........replace that thermostat.
Link Posted: 6/29/2015 8:16:13 PM EDT
[Last Edit: 6/29/2015 8:16:23 PM EDT by turbosc20]
Could it be the infamous GM Dex Cool coolant sludge syndrome? I think that was during the late 90s early 2000s.
Link Posted: 6/29/2015 8:22:58 PM EDT
Link Posted: 6/29/2015 8:23:42 PM EDT
[Last Edit: 6/29/2015 8:26:02 PM EDT by moprint]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By medicmandan:


I only ran the red stuff in there for the first 75K miles. First coolant change went to the green.
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Originally Posted By medicmandan:
Originally Posted By HatinHillbilly:
Your plugged heater core is telling you you're radiators plugged also
That red coolant is notorious for it .... you can blow it out of the heater core but you probably need a new radiator unless a shop will clean it for cheap.
They don't cost much if you know someone that can get the shop price at NAPA .... probably under 100.00 bucks.
Don't scrimp on this shit ... the bill for blow head gasket - cracked head - or new motor will have you wishing you didn't cheap out.


I only ran the red stuff in there for the first 75K miles. First coolant change went to the green.


Did you get all the Dex-Cool out of the system? If not when you add green to Dex-Cool it will turn into sludge and clog the radiator and heater core. GM was fuking retarded going to Dex-Cool. Also if you replace the thermastat drill 2 3/16" holes in the sides that way if it ever gets stuck shut you will still be moving coolant.
Link Posted: 6/29/2015 8:24:36 PM EDT
Id start with the Thermostat.

Have you checked your fan clutch?
Link Posted: 6/29/2015 8:26:12 PM EDT
I'd be leaning towards an air pocket on the thermostat from leaky intake manifold gaskets.

Yes, they will continue to blow out every 4 years or so, as long as the car lives.
Link Posted: 6/29/2015 8:26:24 PM EDT
Link Posted: 6/29/2015 8:26:51 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By HatinHillbilly:
Your plugged heater core is telling you you're radiators plugged also
That red coolant is notorious for it .
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Toyota Red OTOH is awesome. I was shocked when I saw the inside of my thermostat housing when I replaced the thermostat over a month ago on my 2003 Tacoma. I do a coolant flush every 4 years



Link Posted: 6/29/2015 8:27:05 PM EDT
Link Posted: 6/29/2015 8:27:59 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By medicmandan:


Both fans are electric.
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Originally Posted By medicmandan:
Originally Posted By smithc6:
Id start with the Thermostat.

Have you checked your fan clutch?


Both fans are electric.


So its voltage that tells the fans to spin faster to pull more air through the radiator? Has that been checked?
Link Posted: 6/29/2015 8:29:41 PM EDT
Link Posted: 6/29/2015 8:31:15 PM EDT
[Last Edit: 6/29/2015 8:32:47 PM EDT by moprint]
OP have you pressure tested the cooling system? You can rent the tools from your local parts store to do this and find a video on youtube on how to do it. That and the thermastat would be the first things I would do. It runs cooler with the AC on because the fans run all the time when it is on. They are not variable speed either on or off.
Link Posted: 6/29/2015 8:35:45 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By medicmandan:


Nope. Both fans run with the AC on. It didn't cross my mind that they would be variable speed.
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Originally Posted By medicmandan:
Originally Posted By smithc6:
Originally Posted By medicmandan:
Originally Posted By smithc6:
Id start with the Thermostat.

Have you checked your fan clutch?


Both fans are electric.


So its voltage that tells the fans to spin faster to pull more air through the radiator? Has that been checked?


Nope. Both fans run with the AC on. It didn't cross my mind that they would be variable speed.


There are 3 fan relays IIRC. They are set up to allow the fans to run in series on 6V each for a low speed and in parallel on 12v for high speed. The only electric fan problems I have seem on GM cars is cop cars that idle all day with the A/C on tend to overheat the relays and fan motors tend to crap out every 200,000 miles or so on all of them.
Link Posted: 6/29/2015 8:37:12 PM EDT
Yes thermostat first .... but if no and its holding pressure a rad shop will check the flow of you're radiator.
Link Posted: 6/29/2015 8:40:22 PM EDT
Link Posted: 6/29/2015 8:43:43 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By medicmandan:


Nope. Both fans run with the AC on. It didn't cross my mind that they would be variable speed.
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Originally Posted By medicmandan:
Originally Posted By smithc6:
Originally Posted By medicmandan:
Originally Posted By smithc6:
Id start with the Thermostat.

Have you checked your fan clutch?


Both fans are electric.


So its voltage that tells the fans to spin faster to pull more air through the radiator? Has that been checked?


Nope. Both fans run with the AC on. It didn't cross my mind that they would be variable speed.


When the car heats up, what tells those fans to pull more air through the radiator? If youve just replaced water pump, and dont suspect the radiator or the thermostat, thats what Id look at, especially the way you describe it heating up.
Link Posted: 6/29/2015 8:44:03 PM EDT
on rock auto a thermostat is $4 and a radiator is $80. i would try the thermostat first and them try a radiator.
Link Posted: 6/29/2015 8:44:18 PM EDT
If its boiling when you stop you need to change the radiator cap. Had the same issue on a Camaro a few years ago. Figured it out after changing hoses, thermostat and water pump.
Link Posted: 6/29/2015 8:45:38 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By medicmandan:



They only seem to run with the AC on, regardless of engine temp. I can think of one relay in the main box for the fans, I'll have to look closer.
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Originally Posted By medicmandan:
Originally Posted By Mossberg:

There are 3 fan relays IIRC. They are set up to allow the fans to run in series on 6V each for a low speed and in parallel on 12v for high speed. The only electric fan problems I have seem on GM cars is cop cars that idle all day with the A/C on tend to overheat the relays and fan motors tend to crap out every 200,000 miles or so on all of them.



They only seem to run with the AC on, regardless of engine temp. I can think of one relay in the main box for the fans, I'll have to look closer.


I have a rusty recollection of low coming on at 214 and high at 231 without the A/C on. I don't remember if your car has a separate fan switch in the head or it is ECM controlled off of the fuel injection coolant temp sensor. You may have to monitor with a scan tool to check proper function. A/C will override and turn the fans on to cool the condenser.
Link Posted: 6/29/2015 9:23:56 PM EDT
My has a 07 Pontiac that would burp out the coolant after you shut it off. It was a bad radiator cap it would not hold any pressure.
Link Posted: 6/29/2015 9:27:17 PM EDT
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