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Hello everyone! I have a 2005 Grand Prix GXP. 163000 miles. Posting to see if I can get some help with the temperature on my transmission.
August 2017 I had the transmission replaced. The mileage was approximately 161000. I lived in Florida at this time. Very reputable shop did the work for me. An ex GM technician who was building Transmissions for over 25 years. Transmission worked great. Average temperature in Florida for the transmission was 165 degrees to 170. September 25th of this year move to North Carolina. Just south of Charlotte.
just in the last couple of days I noticed my transmission temperature reached well over 200 degrees. Yesterday reach 210 degrees. Reason why I checked it was I could briefly smell a burning fluid. I knew it was either power steering or transmission fluid. I checked my garage and I am not losing any fluid. Also I am not in a hilly environment where the tranny is working very hard. If anything the weather here was 69 degrees yesterday with no humidity. I checked the fluid and it is right where it should be nice and clean . Transmission works fine with no issues. I know I've been told to put a tranny cooler by other members on the GXP Facebook page but I'm a little bit hesitant because if there is a problem with my new transmission I would rather get that attended to as it still has warranty.
I called the transmission shop yesterday and they it is running a bit warmer than it should. They told me to monitor it and let them know the outcome at the end of the week.
I'm posting this issue to see if anyone else has any ideas of what it could be?
Warranty or not, a transmission cooler is required anyway... so just get one installed.
Kinda surprised your 25 year GM tech didn't simply "force" one on you... but from the sounds of it they simply replaced your transmission with the same POS that comes stock. To be brutally honest you don't really need a 25 year tech to re and re a transmission.
If you are beating down on the car at every other stop light and or passing people on the highway etc... then I can see how you might get 210F in Florida without a cooler installed.
Thanks for the info. I didn't think it would mess with the warranty either. I will definitely look into getting a cooler. Not something I have installed before , probably notnthat hard to do.
The phrase I hear a lot is "heatsoak" that explains a lot, at least to me. When I first got my '08 GXP the tranny got "built" when it was re-built , but I didn't put a cooler on it right away. First long trip <4 hours 80 deg ambient, interstate, 80-90 mph avg.> the trans temp just kept climbing over time. 190, 196, 206, 212 at the first food stop. Every damn thing under the hood is Aluminum on these cars, and as everything heats up, the trans can't lose enough heat to stay reasonably cool. Even under mild use and outside temps. Temp mass and inertia is too much for the stock radiator cooler, Heatsoaked.
I pulled the small aux trans cooler off of a 2000 GMC van. Stuck it if front of the radiator in Series after the stock cooler. 10k later, it might see 202 now, if It's warm, and I'm beating the p*** out of it. Usually it *might* warm to 180 if its summer.
Some people swear you have to get a big honkin solo cooler to replace the Rad cooler, but that sucks because the Trans is never warmed up to operating temp by the engine coolant. Trannies like running at 140-160.
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Transmission Tempurature 
