2025 GMC Sierra 2500 6.6L Duramax Transmission Leak

[Jrod.Milton]

Shortly after returning from a 450 mile (round trip) hunting excursion I took with the truck last week, I noted that the truck was apparently leaving half dollar sized oil spots on my clean driveway wherever it was parked.  Have owned this 2025 2500 for less than one month and at 1,180 miles I crawled underneath to see if I could isolate the leak that was staining my otherwise pristine driveway.  Indeed, I noted transmission fluid seepage on the driver side rear corner of the transmission pan.  I drove it to the GM dealer and the service rep crawled under the truck and also noted fluid around the pan; worse yet, he said he thought he could feel fluid on the top front side of the pan which suggests bigger problems with an eye toward the transmission (seals, whatnot). The truck has been with the dealer for several days and I'm still waiting to receive diagnostics report and a repair recommendation.  I have read other relatively current posts here from other model year 2024 GM 2500 owners with fluid leaking from the 10-speed Allison Transmission at very low mileage and this has me a tad worried and annoyed. 

 

Needless to say, this is a huge disappointment in GM quality assurance, not to mention a colossal inconvenience because I cannot otherwise use my new truck.  After all, who expects their brand new $90K+ truck to have major mechanical issues?   I'll provide an update whenever I hear back from the dealer.

[GMCustomerService]

4 minutes ago, Jrod.Milton said:

Shortly after returning from a 450 mile (round trip) hunting excursion I took with the truck last week, I noted that the truck was apparently leaving half dollar sized oil spots on my clean driveway wherever it was parked.  Have owned this 2025 2500 for less than one month and at 1,180 miles I crawled underneath to see if I could isolate the leak that was staining my otherwise pristine driveway.  Indeed, I noted transmission fluid seepage on the driver side rear corner of the transmission pan.  I drove it to the GM dealer and the service rep crawled under the truck and also noted fluid around the pan; worse yet, he said he thought he could feel fluid on the top front side of the pan which suggests bigger problems with an eye toward the transmission (seals, whatnot). The truck has been with the dealer for several days and I'm still waiting to receive diagnostics report and a repair recommendation.  I have read other relatively current posts here from other model year 2024 GM 2500 owners with fluid leaking from the 10-speed Allison Transmission at very low mileage and this has me a tad worried and annoyed. 

 

Needless to say, this is a huge disappointment in GM quality assurance, not to mention a colossal inconvenience because I cannot otherwise use my new truck.  After all, who expects their brand new $90K+ truck to have major mechanical issues?   I'll provide an update whenever I hear back from the dealer.

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[Jrod.Milton]

Just heard back from the dealer service rep on the tranny leak.  Evidently, the GALLEY PLUGS are leaking at the rear of the Allison Transmission.  They are awaiting parts and will remove and reinstall the OEM factory plugs to hopefully solve the problem in a couple of days.  Was told it is a fairly non-invasive repair and as long as it is indeed the cause of the problem AND it can be successfully mitgated, I'll be glad to have this rig back on the road again.  I realize S(tuff) happens, but I'm increasingly disappointed in GM quality assurance as a result of this.  I've owned nearly a dozen GM trucks in the prior 30 year period and never had (or heard of) issues like this occurring (from 5 seconds after I owned the truck).  Get your S(tuff) together GM team!!

[newdude]

7 minutes ago, Jrod.Milton said:

I realize S(tuff) happens, but I'm increasingly disappointed in GM quality assurance as a result of this.  I've owned nearly a dozen GM trucks in the prior 30 year period and never had (or heard of) issues like this occurring (from 5 seconds after I owned the truck).  Get your S(tuff) together GM team!!

 

 

Sadly its all brands right now, not just GM.