Overheating Issue

[Big Poppa Pump]

2005 Grand Prix
244,000 Miles

Routine maintenance done periodically over the years. Had overheating issues in the past. Nothing more than thermostat, flushes and refills. Well, things have changed a little bit around 243,000 miles. Overheated, dipped a little bit into the red, external leak. It looked like the leak occurred near water pump. Replaced water pump and thermostat and it was still leaking/overheating. Pressure tested and found leak at tension assembly. Replaced tension assembly, pressure tested again, no leaks, but still running hot. So, after replacing water pump, thermostat and tension assembly, the picture shows current temp. Nothing else has been replaced. Cooling fans run. No radiator/hose leaks. Factory radiator, hoses, coolant sensor, etc... Where do I go from here?

Also, on my temp gauge, what are the temp markings, since it doesn't show any numbers? What do you consider "normal" running temp? Maybe the needle pointing towards the top of coolant icon? Maybe 4-5 markings lower?

Thanks in advance.

[02NavyBlue]

From bottom to top I believe the large lines indicate: 160, 200, 210, 240, 260

That's not too bad of a reading for warmer weather. I'd make sure the system is full and completely bled of air. Also make sure there are no plastic bags or other debris in front of the radiator/condenser. That often causes overheating when everything else in the system is fine.

[Fivefingerdeathpunch]

Honestly if it was my car, I would try re-bleeding the cooling system and see what happens. If the temp gauge seems to stay in the same area then I would end up replacing the radiator as the last piece to the puzzle.

Most cars will run exactly in the middle on a stock temp thermostat which is a 195*.

[nik12937]

Your temp sensor could just be reading innacurately, mine never went above the second big line until I replaced mine, it was giving a false reading. No clue as to why.

[Chadgervais]

On the 04+ The bottom line is 140, next big line is 175ish, middle is 210. I cant say for certain what the highest lines are. Your pics indicate the highest my car has been run under my ownership, that line is 230.

230 is not crazy stupid hot, but if mine were running there, i would definitely looking for answers. One line below that is 220. That is the highest "ideal" temp, and should only be seen if you have been idling for a few minutes. You want to see 195-210, thats perfect. Halfway between the quarter mark and the half is 195-197.

[02NavyBlue]

On the 04+ The bottom line is 140, next big line is 175ish, middle is 210. I cant say for certain what the highest lines are. Your pics indicate the highest my car has been run under my ownership, that line is 230.

230 is not crazy stupid hot, but if mine were running there, i would definitely looking for answers. One line below that is 220. That is the highest "ideal" temp, and should only be seen if you have been idling for a few minutes. You want to see 195-210, thats perfect. Halfway between the quarter mark and the half is 195-197.

Thanks for clearing that up. Do you remember a post on these forums where someone posted a picture of the 04+ gauge and edited the numbers in the pic? I was trying to find that for this post but couldn't.

[Big Poppa Pump]

Thanks for all the help.

I did a re-bleed and changed out the temp sensor. So far, this is where it stands now



So it looks like I am sitting around 195-200? If so, this is where I believe it always used to run prior to any issues. I used to live in Pittsburgh, PA and just relocated to Dallas, TX 3 months ago. Looks like my car has to adjust to the temp change around here. Maybe it will run a little warmer than before. We'll see how it goes during my daily driving around Dallas on Monday. Thanks again for all the help.

[nik12937]

Thanks for clearing that up. Do you remember a post on these forums where someone posted a picture of the 04+ gauge and edited the numbers in the pic? I was trying to find that for this post but couldn't.

I legitimately looked for almost an hour for that picture about two months back, it was very helpful. But since you mentioned it, I got too curious, and after using a crazy combinations of quotes and other special handles, I just found it using Google. Here's the link to the thread it was posted in (credits to Chadgervais), but I'll copy the image URL here too so it's easier to find.

http://www.grandprixforums.net/temp-gauge-75307.html



I wish more people used tags in their threads, it makes finding stuff with the forum's search engine much easier.

[tms8582]

You look to be good now but if you want to run a little cooler you can buy a 185 t stat

[Big Poppa Pump]

Well, here I am tonight, after about 1 hour of straight driving





And I'm pretty sure it'll go higher in Dallas heat & traffic.

185 t-stat you say? I'll try that too.

I may end up flushing radiator or just getting a new one.

Cool find on the gauge numbers pic nik.

[02NavyBlue]

Well in your situation I don't think a lower t-stat will help much. As of now, a correctly operating 195° t-stat at 212° engine temp, would be just as wide open as a lower temp t-stat. Going lower is for when you want your car to run at lower than 200°. What coolant is in the car as of now? I'd flush the system and replace the t-stat with a 195°(stock temp) And did you make sure nothing was blocking the front of the radiator/condenser? It seems to be running right at the temperature that the cooling fans come on, meaning more air flow is what's keeping it cool.

[Big Poppa Pump]

Well in your situation I don't think a lower t-stat will help much. As of now, a correctly operating 195° t-stat at 212° engine temp, would be just as wide open as a lower temp t-stat. Going lower is for when you want your car to run at lower than 200°. What coolant is in the car as of now? I'd flush the system and replace the t-stat with a 195°(stock temp) And did you make sure nothing was blocking the front of the radiator/condenser? It seems to be running right at the temperature that the cooling fans come on, meaning more air flow is what's keeping it cool.

I figured running lower than 200° in Dallas heat is what I should be shooting for. As for what coolant is in right now is, last flush and refill was about 60,000 miles ago and is the orange dex-cool. But recently, with the leaks, t-stat, water pump and tension assembly replacement, it's been topped off with the prestone 50/50 and water. Nothing is blocking the radiator/condenser.

[tms8582]

You dont want to mix dexcool and the green stuff. Most on here will tell you to flush it out. I use universal coolant but others use the green. Its pretty much agreed upon to stay away from dexcool. looks like your at 210 now which is where the fans come on. Im guessing you were sitting still when you took the last pic correct? does it cool down a bit once you start rolling? If so everything looks to be at factory specs. If you want to run cooler the pcm will have to be reprogrammed.

[Dagriffi]

Have you done your LIM gasket yet? I pulled all sorts of sludge out of my head doing that. It also fixed my overheating problem.

[The Guz]

You dont want to mix dexcool and the green stuff. Most on here will tell you to flush it out. I use universal coolant but others use the green. Its pretty much agreed upon to stay away from dexcool. looks like your at 210 now which is where the fans come on. Im guessing you were sitting still when you took the last pic correct? does it cool down a bit once you start rolling? If so everything looks to be at factory specs. If you want to run cooler the pcm will have to be reprogrammed.

I would have to agree. It loos like your car is running within the factory specs. Check to see if the needle goes down while you are cruising. If it does you are fine. I'm going to assume you are using the 50/50 that mixes with everything. If not liek it's been stated you don't want to mix dexcool and the green stuff. Also if yo maintain dexcool it works fine.

Have you done your LIM gasket yet? I pulled all sorts of sludge out of my head doing that. It also fixed my overheating problem.

His should already have the aluminum gaskets considering he has an 05.

[Below Average Joe]

not all 05's have aluminum intake gaskets

[TDgrand]

I have a 05, it had plastic LIM gaskets. Upgraded to GM aluminum.

As for the temp, mine runs that same as yours. It fluctuates back and forth depending on driving conditions.

I tried a 180 t-stat and ran into issues in cooler weather, was setting off engine code. So went back to 195. I have heard the temp fluctuation is normal.


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[robinsone]

I suffer from the exact same thing. Here's what I've done

Coolant elbows, LIM, coolant flush, coolant sensor, thermostat, and I even swapped out the relays to the radiator fans. It runs that hot normally if i'm not running the A/C, which kicks on the 2nd fan automatically when the A/C goes on. So my guess is the primary radiator fan may be wearing out, but then again I don't exactly know the exact process of how and when the fans kick on, other than with the A/C going on.

What I'd love to do is stop by a dealership and ohm a set of new radiator fans and then compare to mine. Not sure if there is a spec sheet on it in the service manual I just haven't been able to find it. It's just an idea to at least eliminate the radiator fans as a potential culprit, but I could be off in my assessment. Would love to hear someone else's thoughts on this.