Dying Allison?

1RUSTYRIG · March 10, 2005

Hey Guys...first of all, great forum. Secondly, sorry to come here on a sour note.

I have a GMC 2500HD with the 8.1 and the Allison. The truck has 53K miles on it and it has never towed anything over 5K lbs.

The last few months I have witnessed some really strange behavior. It started with the truck "slipping" into what appeared to be neutral when accelerating from a dead stop. I never felt it slip out of drive, but cycling from D to P and back got me going again.

Tonight I was driving and I think I felt the tranny slip out of gear and then engine promptly died. I got it going again and it did the same maneuver 2 more times while driving at speeds of 45+ MPH (first time was ~5 MPH).

The tranny has been shifting hard for awhile and I am thinking torque converter...I don't see any recalls on the allison but it seems like everyone that I meet with similiar trucks is having tranny issues.

Any help would be greatly appreciated. I really don't have any desire to pour thousands of dollars into this truck after "prepaying" for what I assumed to be a heavy duty drive train.

Kevin

whitesnake01 · March 10, 2005

If it was mine, I would take it to a reputable transmission dealer right away. Every day you drive it like that will only rack up repair costs. HD or not, the problem appear to get worse not better each day you use it. Why would the engine stall? Did the tranny not disengage?

What do you know about its service history? Did you buy it new?

1RUSTYRIG · March 10, 2005

If it was mine, I would take it to a reputable transmission dealer right away. Every day you drive it like that will only rack up repair costs. HD or not, the problem appear to get worse not better each day you use it. Why would the engine stall? Did the tranny not disengage?

What do you know about its service history? Did you buy it new?

<{POST_SNAPBACK}>

I bought the truck brand new. And I would tend to agree with you that it will be getting worse, but the problem is very intermittent. I am trying to localize the problem, or find if others are having/had similiar issues before taking it in. "reputable" and "transmission dealer" are almost oxy-morons these days and the stealership will replace everything around the problem until I rack up a $4K dollar repair bill.

Now that I am done ranting

I haven't been able to pull any fail codes from the computer. I had a warning on the evap canister a month ago but that was a loose connection on the sensor.

I am not sure why the engine would stall. A guess would be the TC locked up and stalled the engine...but that is just a guess. There have been occassions where it appeared that the trans dropped into neutral only to slam back into drive after several seconds of coasting (45 MPH).

Hope the additional info is helpful...

Kevin

Cool Zr2 · March 10, 2005

Sounds like your fluid is low, have you checked it?

1RUSTYRIG · March 10, 2005

Sounds like your fluid is low, have you checked it?

<{POST_SNAPBACK}>

You're kidding right? Yeah...I checked the fluid.

Anyone here want to offer some tech up? Anyone else hear of similiar issues with the Allison 1000?

8100 Power · March 11, 2005

HI, i had my torque converter go out in mine at 100,000 miles. It was not shifting hard or dying but it was making this sound when truck was running that was unbearable! It was in the shop for a month a cost only $1200.00 !

billcar9999 · March 12, 2005

You don't say what year you have but I had a similar but less extreme problem. The dealer updated the software and the problem went away. It was difficult to explain it to the dealer in way that made them understand that it needed an update. Here's the messages I got from one of the boards a while back. It may help you explain (or understand) what's happening. Hope it helps.

****

The neutral condition which exist on early 1000 series is corrected by a software down load by your dealer through the tech 2 i have a 2001 8.1 and 1000 and had this problem. I called around and for my truck with 4.10 ratio, the gm part # for the down load is 15077862. Works like a charm. When you get done the transmission will be in fast adapt and will have to learn again. I suggest you run thru different ranges (starts, stops, etc).to let it learn quickly. Hope this helps you out.

I’m sorry I didn’t get back to you quicker. What was happening is as you came to a rolling stop that the range selected, range attained and range commanded was being observed. When the trans made the down shift, the range commanded by the transmission computer was neutral and then came back to first range thus you felt the several second time lag when the unit came back to range. I should have noted in my first post that the software level shows up on the dealer’s reader as mof. After the new software is loaded this level changes to 14.as you have probably guessed by now I do have access to some Allison info.

bluenote · March 12, 2005

If you are going to go to a transmission shop and are wondering what might consititute "reputable," then I'd suggest going straight to an Allison dealer/shop. We have a couple of them in my area and they know WAY more about these beasts than anyone at a GM delaership.