2020 2500HD AT4 - 17K miles - Allison leaked and -REBUILD- 1500m from home

Kaamacat · October 7, 2021

Just returned from a 10mth planned lifetime trip that never happened. About 1500m from home (w/only 17K miles) the Allison started a slow trans drip. Ended up needing a pull a rebuild of seals and stranded in a RV Park for 18days. Made it home fine, AT4 ran excellent but honestly unsure of the safety for any future trips. ANY SUGGESTIONS on how I might go about recovering the total loss for the trip. (Planned 10mths, my 65th bday Out-West trip with family that never happened). Honestly shocked it happened to what should be a tank of a vehicle.

FYI.... Trailer only weights 6000lbs (which is a nothing for the AT4). Kept about 65mph on average over total highway, so not even a strain at any time. (Note that the technician pointed to a specific seal within the center of the trans, wondering if this is a known item in advance for potential failure. They had to order ALL the seals and seal kits for the unit) But yes, they pulled everything out behind the engine as it sat until it was back alive 18days later..... then the return home. (GM may need to rethink those AT4 ads on tv)

diyer2 · October 7, 2021

Things break or have problems. It was fixed so I would continue with my plans.

We just had our car fixed under warranty. 26 days at the dealer waiting for a starter.

Kaamacat · October 7, 2021

The issue becomes....is there something cast improperly within the trans, or, was it just a bad set of seals from Allison, or even during assembly done poorly. With a vehicle barely 1yr old, paying almost 80K for what should be the best-of-the-best with the Duramax and Allison (not to mention wife and I burning 3wks of vacation for nothing).... Leaves a sour taste BUT we love the AT4. Think about being stranded 1500miles from home..... Would you attempt a long trip again. (Whole different ballgame). Could have turned out much much worse had we continued out of Gallup NM up to Moab and the trans died vs me spotting the leak in Gallup.

CRApex · October 7, 2021

Both of mine have been flawless (48k on one and 33k on the other now). I haven't read of any serious issues with the 10spd Allison so I think your experience is probably isolated, bummer though.

diyer2 · October 7, 2021

I'm not trying to give you a hard time. It is what it is.

Why worry about something that may not happen and I understand you're frustration and lack of confidence in the truck. It's still a massed produced product no matter what it cost.

Just had a conversation the other day with the owner of 21 3.0 diesel. It was repaired 4 times under warranty but has been flawless the last 15 K miles.

If your looking for a guarantee it will not have any more problems, good luck.

Drive it and see is all you can do.

Kaamacat · October 7, 2021

Just got off the phone with the tech that did the rebuild. He said that when he initially called it in to GM, that their Techline knew exactly what the issue was, which has to do with some teflon seals that must be resized to fit...etc. (A known issue). Which now makes more sense since he showed me an exploded pic of the Allison before they dropped it and had an arrow pointing to a specific seal area.... The work order though was showing a total of 9 seals and one line item was a kit. I am thinking the tech that did the rebuild probably did a better job than the initial line builders. This guy, you could just see talking to him, had some excellent work ethics. (In fact everyone we met there was outstanding).

dalek77 · October 22, 2021

Just crawled under and saw this..... My buddies 2020 is doing the same thing. 17k miles

Kaamacat · October 25, 2021

dalek77.... any news from your friend on what the dealer says that leak is? From the area, that is below the tq converter and could be a seal more forward, or from the converter to trans. Either way not good to see. (And in all of this, if you were to ask anyone..... even Ram, Ford owner and such, the Allison is supposed to be the #1 transmission most wish they had).

dalek77 · October 26, 2021

6 hours ago, Kaamacat said:

dalek77.... any news from your friend on what the dealer says that leak is? From the area, that is below the tq converter and could be a seal more forward, or from the converter to trans. Either way not good to see. (And in all of this, if you were to ask anyone..... even Ram, Ford owner and such, the Allison is supposed to be the #1 transmission most wish they had).

Looks like I'll be the first to go to the dealer next week. Out of like 5 trucks of people we know, they're all leaking around that inspection cover.

Carolina · August 29, 2022

I mean really who comes up with this crap to remove the full tubes off the transmission. The manual says generally transmissions don’t need to have fluid added so it was removed. Crap happens and it would nice to be able to add freaking fluid to get you home or somewhere

Kaamacat · August 29, 2022

Most disturbing items were... The dealer (Colonial Buick GMC) where we bought it from, when called to ask for any assistance had zero interest. The tech at the Chevy dealer in Gallup (these guys were great), knew exactly what seal was defective in the center of the trans (exploded diagram) because Chevy told him which it was. So GM knew there was a defect. And to top this off, this trip had been planned literally for 1yr.... lots of $$ lost on items purchased, reservations made at RV sites... Vacation time wiped out. (GM would only recover $750 worth). Had someone offered a new Ford or RAM for trade the AT4 would be history. NOW LET ME SAY... that we have put ~10K on her since and running great (knock on wood). But imagine the feeling when you are so far from home, could have been worse had we continued on... TO THIS DAY the selling dealer NEVER asked how we made out...NEVER. (So when your tech says "Total transmission rebuild" that is a bad day)

KARNUT · August 29, 2022

The trailer is a lightweight. So I would have requested a loaner. If that didn’t work either traded it in right there. Or bought another truck and sold the fixed one later. Any diesel is going for big bucks. You could have finished the trip even if you couldn’t have taken the trailer. But at 6K even a half ton would have done the job. Last thing I would have done was bailed on my trip.

Kaamacat · August 29, 2022

Nothing within 200miles to replace with.... And part of the trip was using the AT4 sitting up nice and high to disconnect and see the sights from "up high". The loaner we got was a small SUV from Enterprise (very small), but still having the AT4 was part of the total experience. (And the trip did not really start yet... next stop was Monument Valley where the real vacation was to start... then onward to Lake Powell/Lone Rock, Yellowstone, BadLands... 100% all in the toilet). So when people asked how the vacation was... "Well, we left on 9/9... arrived in Gallup 9/12... truck broke... got truck back on 9/28... drove 1500miles back home" You just can not replace a year of planning... I'm not celebrating my 65th birthday again for this trip... (unless time travel is possible). And you should only know how many times the "should-a bought a Ford" came up from people with zero political skills. Again. Being 1500 miles from home, stranded, two jobs to think about... and pets with us... Whole different ballgame than if you just died in town.

KARNUT · August 29, 2022

1 minute ago, Kaamacat said:

Nothing within 200miles to replace with.... And part of the trip was using the AT4 sitting up nice and high to disconnect and see the sights from "up high". The loaner we got was a small SUV from Enterprise (very small), but still having the AT4 was part of the total experience. (And the trip did not really start yet... next stop was Monument Valley where the real vacation was to start... then onward to Lake Powell/Lone Rock, Yellowstone, BadLands... 100% all in the toilet). So when people asked how the vacation was... "Well, we left on 9/9... arrived in Gallup 9/12... truck broke... got truck back on 9/28... drove 1500miles back home" You just can not replace a year of planning... I'm not celebrating my 65th birthday again for this trip... (unless time travel is possible). And you should only know how many times the "should-a bought a Ford" came up from people with zero political skills. Again. Being 1500 miles from home, stranded, two jobs to think about... and pets with us... Whole different ballgame than if you just died in town.

A good part of my working life involved pulling a fifth wheel. I did have one failure in forty years. Luckily there was several other to use while mine got fixed. My trips retired don’t involve rigs anymore. I did consider renting during Covid. All said and done you can’t let one failure be the judge.

KARNUT · August 29, 2022

5 minutes ago, KARNUT said:

A good part of my working life involved pulling a fifth wheel. I did have one failure in forty years. Luckily there was several other to use while mine got fixed. My trips retired don’t involve rigs anymore. I did consider renting during Covid. All said and done you can’t let one failure be the judge.

You mentioned Ford. From what I’ve read all the diesels are comparable. Ford seems to have the edge in camper driving aids. Something I never needed or wanted. To many electronics for my taste.