Allison Transmission problems http://www.dieselplace.com/forum/smileys/Cry.gif


I have a Chevrolet 2002 Duramax with the Allison transmission, This is a C2500 four wheel drive extended cab pickup and up until now I have had no trouble with the Allison (in fact its a great transmission) The problem goes like this I now have about 102,000 miles, the truck has always been serviced by the dealer at the appropriate times including the transmission. While driving down the road somewhere around 62 mph all of a sudden the engine just revs up, as I release the throttle you can feel the transmission catch or take control again. This happened about six times on Monday and Tuesday morning while enroute to the Chevrolet dealer it was worse. Before I made it to the Dealer it would not shift into overdrive and as I came to a stop about a mile before the dealership, I heard like a grinding glass noise, as I pulled into the dealership the glass noise was gone.



The dealership called today Friday and said it was fixed, that a module had to be replaced. To replace it they had to pull the transmission back a bit from the engine to get to it. As it was explained to me the computer had put the engine/transmission into what they called limp mode (when it would not shift into overdrive) I picked up the truck and was told that the tail piece needed a seal that it had a very minute leak and they ordered the seal but I could go ahead and use the truck until next week when the part comes in and thuis far the part they installed was around twelve dollars, I thought wow and I thought it was real serious.



Well after driving about ten to fifteen miles it started again around 62 mph it just like slips out of gear and the RPMS go way up and you hear the roar of the engine I let up on the accelerator it like takes hold and works ok for maybe four or five miles and then again the same thing.



Today after reading this forum I just knew what the problem was I went out and looked at the spin on filter and it was not new so I went and got one at Napa, Tuesday I will get a factory Allison as the Napa plugs all the holes with the magnet so I left the magnet off just to test drive and see if it was fixed. After about three miles at around 60 mph it slipped and RPMS went up, as I let of the accelerator you could feel the transmission reconnect or whatever but about a mile down the road I pulled over to turn around and it happened just as I was comming to a copmplete stop and you could here this strange noise like a gear or something going around free wheeling, anyway at a complete stop this was going on so I went to put the transmission in park and you could here it louder and then it like clicked and locked and then I was ok. Oh and the computer now has the transmission back into limp mode once again.


I would appreciate all help with this issue I have been a die hard Chevrolet diesel customer since 1988 and I really have enjoyed this truck since new and I really thought that with the Allison I would not ever have any tranny problems


My fluid does not smell bad or burnt and its a clear red color of course the dealership said to just bring it back on Tuesday and we will try again they had it since Tuesday and I was told there were four of us with tranny problems





Thanks to all who reply


Terry

It sounds like you have taken the high gear clutches out (5th) or the torque converter clutch. Your description sounds more like 5th gear clutch sets though. If they will cover you under warranty let them have at it but if no warranty I would see about having it upgraded with a Transgo kit and fresh clutches.

I agree with what Diesel Tech said.


mike

ditto to

I appreciate your replys and help, I drove about sixty miles today with it and tried something, After the first slippage around sixty I slowed down to about fifty and put it in third on the indicator only for it to happen again, does this mean its more possibly the torque converter clutch or can it still be the cluth plates?


The other thing I think strange is after the slippage happens I can give it full throttle and it downshifts just like normal and never slips when under power like this, its just when your cruising that this slippage happens.


Any thoughts on this?


Thanks again


Terry

Not really as C3 is applied in third gear. This confirms more then eliminates a clutch issue.There is always two clutch packs on in each gear.In 3rd C1 and C3 and 5th C2 and C3.


I'm assuming your doing this in non tow haul mode so converter isn't locked also.


Have you ran any performance device? Are you the original owner from new?


Odd you haven't thrown any Codes.


Mac Edited by: Mackin

Hi,


I am the original owner and have no performance updates on the 02 Chevrolet Duramax/Allison 4x4.


The problem happens without towing, however this truck is very heavy it has a American Body with a lift gate and loaded down with HVAC parts and tools.


Yesterday I unloaded a lot of weight including ladder and ladder rack, also today when I drove it I did put it in the tow/haul mode and it still slipped a couple of times but not near as often. As far as the codes are concerned the Dealer had told me it had so many codes it did not make sense, I really don't think they know and I wonder if it could be a computer issue, attached is a picture of the truck with its biggest load aprox 3,000 pounds in fact it is the only time I have ever carried something like this and it was not that far. I really do appreciate everybodys help with this, I just don't want to buy a transmission or rebuild and then be told oh its the computer.


Again Thanks


Terry


http://www.dieselplace.com/forum/uploads/7F1_P1000868.JPG

I doubt the computer would ever cause a slip. It would limp first. Sounds like you smoked the converter clutch. I sure would like to see some codes. Being that you have an '02, you have the early stator bushing and that in itself will take out a converter.


mike

Update,


Well it turned out to be the Transfer case and from what I understand Chevrolet does not have any in stock, there is a bushing inside the transfer case that rubs against the pan and causes the oil to leak out. then with no oil the gears burn up. Chevrolet claims this is not a problem, my brother called to tell me that over the weekend while pulling his boat that his tranfer case leaked oil out and it was all over his boat his is an 01 Duramax/Allison/4x4 with less miles than my 02. The dealer said he hopes to have parts in here by this Thursday so they can rebuild it since he can not get a new one, also he has another one in the bay with the same problem but Chevrolet does not have a problem?


Thanks for all the help and replys!


Terry

That's really interesting.


I know of someone who after a RR of the Allison, rushing to clear the bay, forgot to refill his T-case.


He proceeded to drive 50+ Miles at speeds well over 100 MPH.Still works great,so I here.Guess he's lucky,EH! That's a very eggspensive HD seal in the tail of the T-case. Where exactly did it leak?


Mac