Chevyfan3

He's seeing more diesel trucks with the issue so far but gassers here and there as well. Dmax trucks are more popular in my area so that could be why he is seeing more of those vs the gassers as well.

The drops on the inspection port are the front pump seal issue. Mine had this around 6500 miles. Trans has to come out for this issue to reseal the front pump cover housing.This has been going on since 2020 for this one, there is a TSB for it as well. When the tech put a camera up in the bell housing port we could see how much it has leaked as a good amount was sitting in the bell Housing.

I don't think the problem will get fixed until they redesign the transmission. They have let out go on for 5 years now, it must be an inherent flaw with the 10L or they just don't care to fix it. There have been 25's popping up on the forums with valvebody issues and my buddy who is a tech has seen a few as well. The year he sees the most of are the 24's so far. As far as parts availability goes it's a crapshoot and something GM really needs to get in check, having trucks wait weeks or months for a simple part of ridiculous.

Such a bummer this is still happening to 2025 trucks, GM really needs to get quality under control with these transmissions. Hopefully the reseal works out for you, some don't have luck with it and some do.

No problem. I camped with a buddy of mine over the weekend who is a GM tech and he said the parts are becoming more readily available now and the backlog of trucks waiting for this repair at his dealership she now all gone. The new part # is 24065357.

If you must go to GM I would go with a 25' to hope I escape the 10l transmission issues. I have been looking at the super duty's myself and I didn't find the ride to be that much harsher then my 23' Sierra 2500. I would test drive one to see, If the Ford has been flawless maybe switch to a f250 instead.

Is it leaking underneath? The 10l1000 is starting to become a problem child for these HD trucks and it seems to be getting worse on the 24- up trucks.

Sounds like the valve body issue and you have a 24' model which seems like that year is starting to become really bad for these. Be prepared for a long wait as no parts are available for this and I would stop driving the truck as you can further damage the transmission.

That was my experience with my 16' 6.0 with the 4.10 rear as well. I think part of it was because the 6.0 was underpowered and just lacked the torque when you needed it. That truck made for a very "busy" towing experience.

They might have, you don't hear about the issue as much on 20-up trucks. But after my terrible experience with my 16' 6l90 I wasn't doing that again so I still stuck it out with GM trucks but went to the dmax and 10l1000. Which so far for me hasn't been issue free, before 10k miles it had to be removed for the front pump cover leak and resealed and now hearing a lot about this valvebody issue. So once again I have an hd truck with trans issues, after 25yrs of GM truck ownership I will be moving on when it's time for my next truck. Gm for me hasn't proven that they can build a decent transmission and I'm not going to chance a 3rd truck having issues again.

Your in the sweet spot for 6l90...13' and previous were good units. 14-19 when the body style changed we're trash, convertors were garbage and failed taking out the whole transmission. 20-up Gm seems to of changed the convertors because you don't hear about it anymore really. I had a 16' with the 6l90 and it was terrible, finally let go at 55k and that's was with 10k fluid changes. Just a bad design that gm let linger.

If your truck is destined to have the failure it's going to happen regardless of if you get the software patch or not. You're better off on getting the update so that if you do incur the failure, you can keep you and your family safe while pulling your camper. The software is only 20-22' trucks because 23' up already has it in place from the factory, which also tells you GM has known about this for some time now. I have seen guys with gassers have the issue as well so its not just dmax trucks with the failure and I have seen way more 23-up trucks with it then the 22-previous trucks as well for what thats worth.

Nope the reason I ended up with a 10spd is because the 6l90 in my 16' 2500 6.0 went out at 55k. Torque convertor failure which took out the rest of the trans. I really wish GM would get a grip on their transmission program. For you 6l90 guys GM has a bulletin out for that one as well to replace the valve body plate with a newly designed unit. My buddy had it done on his 21' when he was due for a fluid change.

6l90 has its quirks to and its fair share of convertor issues as well although less common on the 20-23 trucks so far. 10spd the two main issues I see is the front case leak (I had this one) and the valve body issues. Drive a 6l90 truck and then a 10l truck and see which you prefer, that's what it really boils down to.

For the early years that the recall includes no, those were 6l90's. 24' up gassers get the same bum Allison 10spd and can experience the valvebody failure.

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.

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.

Yeah I don't think this problem is with all of them. Mine started to show up around 10k and it leaked worse when I was pulling my trailer on the highway for an extended period of time. Around town I could not get it to leak.

I have seen guys with 24' model trucks still have the issue and my buddy who is a gm tech has seen some as well. Not enough 25's out yet to know if they fixed it or not, hopefully after 4 model years you would think they could get things straight by now.

Glad you got it fixed and sounds like you had a good tech which is half the battle sometimes. Looking at the picture in your thread I had to reread it to realize that wasn't your photo, so maybe they have fixed the front internal cover leak now on these. I have seen the t case leak on the forums, I wonder if it's a bad install like they claimed on the front cover seal as well.

Possibly the latest recall involving this part has something to do with it. They might not have replacements that are not defective yet. How many miles were on your 23' when this happened?

This 10spd is starting to be very disappointing and I have my doubts about it's longevity. My 23' had a leak as well and the trans had to be pulled to fix it, sad to see this is still occuring in the 25' model year.

Will do, I talked to the tech who did mine and they said they cleaned out the bell housing before and after the repair. They even cleaned it once the convertor was back in place to eliminate any residual. So they are thinking this is still fluid leaking from the front cover still.

Did you find a resolution to this issue? I am experiencing the same on my 2023 10spd with 8800miles, had the reseal tsb as well and the leak is back after 200 miles. I am thinking there is more to this issue then just replacing seals.

I agree totally, it at the very least needs a bullet convertor. Issue is the shops around me won't rebuild these units and just install gm remans which won't allow me to upgrade it and keep the warranty. So I'm stuck. Fluidwise it was always changed everyear after camping season, used the Delco fluid and it always looked great. I doubt going to another fluid would of changed my outcome. I think I'm just going to trade the truck off, been a long time Chevy truck owner but maybe it's time to try something else. If I get a newer hd they still have the 6l90e and if I wait for a 2024 I'm going to miss a good chunk of my camping season.