Allison/Flywheel

[ih1466]

A few months ago my truck had 35,817 miles on it and the tranny started to leak around the "bell housing area". I took it in to find out the convertor bolts came loose to the flywheel wrecking the flywheel, convertor, front pump, and I am sure more they did not tell me. Has this happened to any of you??? It looks to me you have to go through the starter hole to check these bolts. Is this something we need to check every 10k or something on our trucks. What would this have cost me if it were out of warranty? I posted this here because I doubt the BB puts the stress on the tranny that the d-max does. I would sure like to buy one of the power boxes for fun , but I know I can't afford to buy a tranny for this truck.

[Duramaxdiesel]

I noticed this on mine this past week. I'm gonna take it in to get looked at. I'm off warranty now but have the extended one. I'll keep you informed. BTW I have the exact truck you have including colour.

[ih1466]

They made it sound like it was a common thing. It should be a recall then. The dealer also said Allison was responsable for from the flywheel through the tranny as far as warranty.I was also told that Allison would cover this problem to 100k if you called Allison yourself to yell after the 36,000.

[IndigoDually]

It is a problem with the '01's only and they have been standing behind them. My brother's rattled the bolts out, they were put back in and about a year later while in for service the dealer told him they heard a "noise" is the trans and they put a new one in at around 25k miles.

John

[dmaxalliTech]

it is common enought that there is a tsb for it. Bolts must be thrown away after removal. you can NOT reuse the t/c bolts should they be removed

[Duramaxdiesel]

A tsb!? Really? Could you please post the tsb number? Thanks.

[Mark A]

same thing happened to 01' that i had. They replaced the transmission in it at 38000 no questions asked.

Mark

[Duramaxdiesel]

They replaced the tranny?!!! Is it that big a problem? I'm not complaining, I'd welcome a new one :D

[dmaxster]

yup replaced my tranny too....it had 48,650 on it....no questions asked....I had to go through the 1 800 222 1020 number though....no one wanted to anything...they wanted money....but called....and they handled it very well I think....but moral of the story.....replaced....free under warranty....I love GM.....
:cool: smile.gif :D

[77TransAm]

First of all, for those who don't want to read any further, the problem was with early trucks and was fixed (before 2002, I believe).

The problem was covered here in detail back when it was more common, but here is a quick summary: the early GM torque converter bolts did not use any kind of "patch-lock" or anti-vibration compound. Since GM tc bolts have used such compounds for a number of years I can't imagine why they decided to switch to a bolt without it, but they did. A number of the '01 trucks had this exact problem (tc bolts losing clamp load and loosening up). For some reason the problem seemed to be mostly in trucks built at one particular plant (IIRC, it was Pontiac, but I won't swear to that).

GM buys the transmissions from Allison and uses their own tc bolt - Allison's bolt DOES have a strip of anti-vibration compound on it. GM installs the transmission and torques the bolts. GM realized that they were having quite a problem with their bolt and redesigned it to use anti-vibration compound. Problem went away at that time.

When the bolts did come loose, the torque converter was able to "wobble" around and run off-center, or simply be driven by only the one or two bolts that were maintaining clamping force. When this happened, usually the side forces would wipe out the pump bushing, and always one of the lugs that was driving the torque converter would crack and you'd get a fluid leak. By then the damage had been done.

Fixing it generally required (at a minimum) a new torque converter. Often a new flexplate was also required, and less often but still frequently a new pump was needed. Some of the early transmissions were entirely replaced because dealers were not allowed to tear into them to replace the pump.

If you have a truck newer than 2001 you'll probably never experience the problem. If you have a 2001 truck that has this problem and it gets fixed (including new torque converter bolts), you'll probably never experience the problem again.

[ih1466]

Thanks for the info. My GM dealer blamed it on Allison. You would have to be brain dead not to put some sort of thread locker on a flywheel or convertor. Any thing that spins or can vibrate needs locktight. That is what holds my whole snowmobile together.