2001 Grand Prix GTP Chronic Overheating Problem

[zepol]

I have had an overheating problem for about 4 years. This happens only when its hot outside and when the AC is running. It doesnt overheat when the AC is not on. I first replaced the radiator cap....then I had the dealership flush the radiator...then I replaced the thermostat....then I replaced the water pump.....yesterday I replaced the hoses that were extremely soft and when I replaced the hoses I noticed some really slimy black stuff that was in the hoses. My thought was that the hoses might be collapsing while im driving because they were so soft. The car is still overheating after replacing the hoses. I started thinking maybe that "melted rubber slime" from the hoses might be inside the radiator causing it to overheat. HELP

[tblake]

Interesting. Are you losing any coolant at all? Take a peek by your injectors and valve covers on both banks. Do you see and leeks? Could be a LIM gasket. Sooner or later all 3100's and 3800's need them rempalced due to bad oem gasket design. (dont even get me started).

[BNaylor]

Do both cooling fans turn on with the A/C on? What does the temp gauge read? Is the overheating only at idle or very low speeds or higher speeds too. The radiator is a good suspect.

[zepol]

Originally Posted by tblake

Interesting. Are you losing any coolant at all? Take a peek by your injectors and valve covers on both banks. Do you see and leeks? Could be a LIM gasket. Sooner or later all 3100's and 3800's need them rempalced due to bad oem gasket design. (dont even get me started).

Not losing coolant.....I have been getting a faulty low coolant light as I have checked the coolant level and it seems to be fine. I don't see any leaks but am not familiar with a LIM gasket. The last shop that had my car in suggested I change some gasket that the supercharger is in the way and would have to be removed. Would this be the LIM gasket?

For the record I do about 80% of my own work on my cars and have done some pretty difficult jobs. However I do not consider myself a mechanic and do not fully understand troubleshooting or things like that. I am only someone that can read instructions very well. HA HA HA. I also have a brother that helps me that isn't a mechanic either but he is the kind of person that has a nack for this kind of stuff. I guess you can say that I do what I gotta do because of resources.

[zepol]

Originally Posted by BNaylor

Do both cooling fans turn on with the A/C on? What does the temp gauge read? Is the overheating only at idle or very low speeds or higher speeds too. The radiator is a good suspect.

Both of the cooling fans work just had them tested at the last shop that I took my car too. He had my car there for about 3 hours hooked it up to his diagnostic machine and said he couldn't figure out why the car was overheating. He told me that I should replace those soft hoses (Did that yesterday) and that there could be some debris between the radiator and condensor coil restricting the radiator. The overheating doesn't happen on the freeway. It seems to happen while driving during stop and go traffic especially when I zip in and out of traffic When I changed the hoses yesterday there was a black slime inside the hoses and on the radiator cap as well as the t-stat. It almost seemed to be like the inside of the hoses had gotten so soft that they sort of melted rubber juice or something.

[tblake]

I forget now, did you have the system flushed?

[zepol]

Originally Posted by tblake

I forget now, did you have the system flushed?

I had the system flushed last year by the dealership. I did this while my car was still under warranty so that they could run a diagnostic on it to see if they could figure it out this year. I had been taking my car to the dealer each summer for them to find out what was wrong and they never could. I eventually got tired of taking it there over and over so each winter I stopped bugging them until the next summer.

I did not have the system flushed recently. Unless you guys have other things I should check, I have pretty much decided to just spend the money and buy a new radiator for 190 bucks and drop it in with my brother instead of dropping any more money on diagnostic fees or any other professional opinions. I think I may save money of the long run by doing this. Should I flush the system before I install the new radiator cleaning out as much of the gunk as possible or should I just remove that radiator and hose out the engine where the hoses go and then instal the new radiator?

Also...I have a bra on the vehicle that I bought from the dealer when I bought the car. Could the bra be causing any blockage making the car over heat? I don't see anything that would cause this but just asking.

[tblake]

Only way to find out is to remove the bra. By over heating, how hot does the temp guage get?

I guess about the only other thing I would do is to get a coolant pressure tester, pump the system up to 16psi and check for leaks.

[zepol]

Originally Posted by tblake

Only way to find out is to remove the bra. By over heating, how hot does the temp guage get?

I guess about the only other thing I would do is to get a coolant pressure tester, pump the system up to 16psi and check for leaks.

I was told by the manager that the shop I had it in this week pressure tested something...is this the same thing or could that have been a different. This is the place that said he had no clue why my car would be overheating.

[SsHaDyGt]

Are you using Dexcool? It should look orange. Also, I would say flush the system replace the thermostat and any hoses that need to be. What were the results of the pressure test?

A waterpump overdrive pulley may be an option.

[BNaylor]

Another option if the OP atill has the stock PCM is to look into getting a re-programmed PCM module where the cooling fan turn on point is set for around 180 degrees. Either a DHP, ZZP, Intense, etc. Also run a 180 degree thermostat.

Otherwise with the A//C off the fans will not turn on until 220 degrees F in low speed and 230 degrees F in high speed. Since this is acting up with A/C on it sounds like the crud blocked some of the radiator cooling lines. Normally the engine should run cooler with the A/C on.

[GTP Version 2.0]

Hey guys. Is it ever possible for the coolant elbows to become blocked? Also what color is the oil? "Chocolate milk" oil usually means a coolant leak, and checking the front O2 sensor will help verify a leak by a black chalky coating and a funny exhaust smell, usually sweet in odor. Besides that, what coolant is being used? Dexcool can't be mixed with the green antifreeze as it causes a precipitate to form and clog the system. I would flush the system with water for awhile and then use the yellow prestone antifreeze which is compatible with both dexcool and green antifreeze.

[zepol]

Originally Posted by SsHaDyGt

Are you using Dexcool? It should look orange. Also, I would say flush the system replace the thermostat and any hoses that need to be. What were the results of the pressure test?

A waterpump overdrive pulley may be an option.

Yup using Dexcool. I didnt flush the system but when I replaced the hoses two days ago I did blast clean water throughout the radiator through the fill up neck and top hose connecter area with a garden hose with a spraty handle thingy. I didn't get any results per say from the pressure test other than the mechanic telling me that wasn't the issue. Also I refilled the system with new premixed 50/50 dexcool.

[zepol]

Originally Posted by BNaylor

Another option if the OP atill has the stock PCM is to look into getting a re-programmed PCM module where the cooling fan turn on point is set for around 180 degrees. Either a DHP, ZZP, Intense, etc. Also run a 180 degree thermostat.

Otherwise with the A//C off the fans will not turn on until 220 degrees F in low speed and 230 degrees F in high speed. Since this is acting up with A/C on it sounds like the crud blocked some of the radiator cooling lines. Normally the engine should run cooler with the A/C on.

I apologize but I'm not familiar with the term OP. I know that I have the stock PCM becuase the car is fully stock with the exception of the 180 t-stat I just threw in there while changing the hoses on Wed. I will look into the re-programmed PCM module. Is it difficult to install? I will be putting a new radiator in the car today....I figure other than sensors I have pretty much replaced the whole system within the past year and nothing has seemed to work. I bet if I would have just done the radiator all my troubles would seem so far away. LOL

[zepol]

Originally Posted by GTP Version 2.0

Hey guys. Is it ever possible for the coolant elbows to become blocked? Also what color is the oil? "Chocolate milk" oil usually means a coolant leak, and checking the front O2 sensor will help verify a leak by a black chalky coating and a funny exhaust smell, usually sweet in odor. Besides that, what coolant is being used? Dexcool can't be mixed with the green antifreeze as it causes a precipitate to form and clog the system. I would flush the system with water for awhile and then use the yellow prestone antifreeze which is compatible with both dexcool and green antifreeze.

Oil seems to be normal in color. I usually do a good job of changing it often and primarily use fully synthetic however last week the shop that I had change the oil thought I said synthetic blend so thats what in there now. I have noticed an sweet smell when my car gets hot in the past but don't remember smelling it recently. I also a while back did top off my freaking coolant with the green crap before knowing what Dexcool was. I was scolded by the GM mechanic at the dealership and vowed never to do it again. Could this have started my problems?