2025 2500 HD Duramax Leaking tranmission

Derek Smay · January 16, 2025

Anyone else having issue with their 2025 2500 HD leaking around the inspection cover? This is my first Chevy truck, and I noticed oil leaking from transmission around inspection cover in bell housing. The dealership where I purchased the truck cleaned out oil and had me drive to see if it was just residual oil. The oil leak continued and now another dealership did the reseal of front seal and whatever else was list in technical service bulletin last week. After about 50 miles truck now leaking again worse than before from same area. Truck only has 2700 miles on it and extremely disappointed after spending $75K that been into shop several times. I'm hoping GM could just send a replacement transmission hate the idea of all these repairs on a brand-new vehicle. It's going back to the dealership on Monday for them to have another look.

Edited March 11, 2025 by Derek Smay

Chevyfan3 · January 17, 2025

Insane that GM is still allowing this to happen and hasn't fixed the issue into the 25' model run. I had this same issue on my 23' and had to have the trans removed for the reseal tsb as well. After that it took some mile for the fluid to stop leaking, I would crawl under the truck and clean it up, pop off that cover and clean that area as well. I think I have about 6k on it now since the repair and it's been dry. I have seen guys end up having the trans replaced though for ones that wouldn't stop leaking so that's a possibility as well. I would clean it yourself and monitor and hopefully it stops, the convertor is tight to install on these transmissions so it can spill some fluid when they put it back together.

I guess GM has decided they are not going to fix this issue on this generation of trucks which is pretty sad.

Derek Smay · January 17, 2025

Thanks for suggestion I’ll give it a try. It’s going back to dealership Monday. It’s dripping pretty good I wiped driveway clean yesterday and here pic from today

Chevyfan3 · January 18, 2025

Mine never got to where it was dripping on the ground like that, it was pooling inside the case though. So you're just be losing fluid at a pretty good rate then. If it's dripping your looking at having the transmission come out again to repair it unfortunately.

I'm really starting to lose my faith in the gm truck product, not fixing known issues like this is ridiculous. The fact I had it in 23' and now your truck 2 years later same issue just shows you the level of commitment they have to improving or turning out a good product.

Derek Smay · January 18, 2025

Crawled under this morning and it’s all around the pan not sure if they would have dropped pan or not. There was very little inside bell housing that I could feel so that may have been from before repair.

Another JR · January 18, 2025

On 1/16/2025 at 11:04 AM, Derek Smay said:

Anyone else having issue with their 2025 2500 HD leaking around the inspection cover? This is my first Chevy truck, and I noticed oil leaking from transmission around inspection cover in bell housing. The dealership where I purchased the truck cleaned out oil and had me drive to see if it was just residual oil. The oil leak continued and now another dealership did the reseal of front seal and whatever else was list in technical service bulletin last week. After about 50 miles truck now leaking again worse than before from same area. Truck only has 2700 miles on it and extremely disappointed after spending $75K that been into shop several times. I'm hoping GM could just send a replacement transmission hate the idea of all these repairs on a brand-new vehicle. It's going back to the dealership on Monday for them to have another look.

Just a friendly heads up that you posted this in the gas engine subforum.