6 speed Allison tranny problem

[skevac]

I have a 2006 2500HD CC SB 4X4 Duramax with 22500 miles. It is stock with the exception of 285 tires and a 4" turbo back exhaust. It has never had any kind of a chip or programmer installed nor has it been raced or pulled. It is my daily driver and I occasionally pull a 24' foot enclosed trailer with a 2500 pound car in it. As I was accelerating hard to get out into traffic 3rd gear acted like it was slipping. So I got out on some back roads and did some further test runs. It shifts fine in 1st, 2nd, 4th, 5th,and 6th. 3rd slips or something all I know is it is not right. There are no trouble codes coming up and sometimes it is worse than others. Anybody had a similar problem??? Thanks in advance.

[DmaxMaverick]

Welcome aboard!

Change your fuel filter, and test again. Let us know what happens.

[madmatt]

sounds like one i had last winter. seemed to do it more if you lifted on the throttle just a bit on the 2-3 shift. Seems the 3,5,reverse clutch piston seal was cut on installation and allowed the apply pressure to leak off enough it eventually burnt the c4 or c5s. Took forever to find the concern as both me and GM engineers were convinced it was a valve body issue. Once in a great while it would set a po777, but not untill the issue went on for a while.

[mmcm267]

Bump!!

Any update???

[mmcm267]

Skevac, I tried to PM you but you don't have any data. I hope the problem wasn't serious and that you post back what the problem was and how you fixed it.:D

[TheJDMan]

When was the last time the transmission was serviced?

[mmcm267]

JDM, he hasn't posted since his initial post. No info in his bio to PM or email.:confused: