'24 2500HD Gasser Allison 10spd Valve Body Issue

[BuckWallace]

Yikes, I would have been pursuing a lemon law buyback if mine was sitting that long. "Sorry, we don't have the part" isn't a valid excuse.

[20L8TSierra24]

On 1/19/2025 at 5:42 PM, silversteverado said:

Update 7 months later. Valve was supposedly shipped in October, but before it even got to dealership they decided it was now the transmission. Called GM complain number and they mention possible buy back. That got denied afterb3 weeks then finally 2 weeks later a transmission arrived at dealership. They say I'll have it in a few days. We'll see. So trucks been sitting 7 months while the ethanol is breaking down and tires probably have flat spots. Apparently there's some sort of compensation in the works. We'll see what that's all about. 

I've had ongoing Trans issues as well. Valve body was done & now a complete unit has shipped. Should have my truck repaired within a couple weeks as well. Hopefully the "updated" Trans will last more than 20k miles.

[No F-bdy Bs]

I heard that the 25' models have a different part # for the respective Allison branded units. 

 

Edit:

I went to Gm Parts Online. The part #s definitely changed between the 24' and 25' models. 

Also, the diesel and gas show different part #s as well. 

 

Now, the question is, did Gm remedy the valve body for the 25'+ models? 

 

 

 

https://www.gmparts.com/parts/body?ppc=GOOGLE_8204474763_19725880749_145011820486_23282530&d_src=313715&d_adsrc=4569404&d_campaign=19725880749&d_site=GOOGLE&d_adgroup=145011820486&d_keyword=gm parts online&gclick=CjwKCAiAiOa9BhBqEiwABCdG8_1WT3l3rKhsriNl2hrVKUEdIVm5y93J9fb-1DpnTRSSgO0UPMB1vhoCtbQQAvD_BwE&gad_source=1&gclid=CjwKCAiAiOa9BhBqEiwABCdG8_1WT3l3rKhsriNl2hrVKUEdIVm5y93J9fb-1DpnTRSSgO0UPMB1vhoCtbQQAvD_BwE&gclsrc=aw.ds

Edited February 22, 2025 by No F-bdy Bs

[453030]

On 2/21/2025 at 6:10 PM, No F-bdy Bs said:

I heard that the 25' models have a different part # for the respective Allison branded units. 

 

Edit:

I went to Gm Parts Online. The part #s definitely changed between the 24' and 25' models. 

Also, the diesel and gas show different part #s as well. 

 

Now, the question is, did Gm remedy the valve body for the 25'+ models? 

 

 

 

https://www.gmparts.com/parts/body?ppc=GOOGLE_8204474763_19725880749_145011820486_23282530&d_src=313715&d_adsrc=4569404&d_campaign=19725880749&d_site=GOOGLE&d_adgroup=145011820486&d_keyword=gm parts online&gclick=CjwKCAiAiOa9BhBqEiwABCdG8_1WT3l3rKhsriNl2hrVKUEdIVm5y93J9fb-1DpnTRSSgO0UPMB1vhoCtbQQAvD_BwE&gad_source=1&gclid=CjwKCAiAiOa9BhBqEiwABCdG8_1WT3l3rKhsriNl2hrVKUEdIVm5y93J9fb-1DpnTRSSgO0UPMB1vhoCtbQQAvD_BwE&gclsrc=aw.ds

We can only hope.  I have read 24 and older repairs get the exact same valve body that keeps failing.  Hope the 25 part is better.

[Pryme]

Would any of you guys with 10spd transmission problems go back to a 6L90 six spd if possible? 

[No F-bdy Bs]

23 hours ago, Pryme said:

Would any of you guys with 10spd transmission problems go back to a 6L90 six spd if possible? 

No way. It's a completely different truck with the 10spd,and once the valve body issue is sorted, it will be gtg. 

Especially for the gas trucks since the trans is rated for literally 2.5x the torque. 

[Chevyfan3]

On 2/23/2025 at 9:10 PM, Pryme said:

Would any of you guys with 10spd transmission problems go back to a 6L90 six spd if possible? 

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.

[Pryme]

12 hours ago, Chevyfan3 said:

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.

I thought they put  a beefier torque converter in the 2020+ trucks. 

[Chevyfan3]

2 hours ago, Pryme said:

I thought they put  a beefier torque converter in the 2020+ trucks. 

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.