Duramax Diesels Forum Truck of the Week
Old 10-19-2019, 06:53 PM
Cougar281's Avatar
Cougar281 Cougar281 is offline
Join Date: Sep 2006
Location: St Louis, MO
Posts: 1,392

Default Seemingly odd noise from 01 Allison

I've had my step-father's 01 Sierra ECLB equipped with the 8.1 and Allison for a few weeks, and I just noticed an 'odd' sound, seemingly from the transmission today. I was sitting at a drive through, and I didn't really 'notice it' until I put the truck in neutral and it went away. The best way I can describe the sound is imagine a belt sander and you have a block of wood against it. While in D, stopped with foot on brake, it's there, shift to neutral, gone, back to drive and it's back. Totally repeatable. The only thing I can think of off the top of my head that might be able to cause it under those conditions would be torque converter - everything else in the transmission should be fully locked up for forward motion in first, with only the torque converter slipping.

Slight back story on it, it currently has 60k-ish on it, and a handful of years ago, the transmission was allegedly replaced with a new or reman unit because allegedly, it was slipping on take off (It was probably at 50k-ish at the time). I'm not sure that I've ever heard of an Allison with such low miles behind a powerplant as 'weak' as a stock 8.1L slipping any of the first three or so gears - as far as I know, USUALLY, 5th is the first gear to go, and if I'm not mistaken even with how 'dumb' the 01 OS was, it would still recognize slip and limp, which as far as I know, it never did. And nobody consulted me at the time. Personally, I suspect it was the carrier bearing/bushing for the two piece driveshaft causing the shuddering that was interpreted as slipping, and the dealer raked him over the coals.

That being said, Mike, do you or anyone else have any thoughts on this? Any other info I can get to help?
'04.5 2500HD Silverado LT CC/LB, LBZ D/A Dark Grey
Metallic, 05+ HD Hood & Grille, 192k and counting
Mike L Trans built by ME.
EFILive, PPE Race Valve, KD Twin Lift Pumps & Billet Fuel Pickup, MBRP 4" "Cat-Back" T409 straight piped.

300.59' 3rd place first pull

Best 1/4 times:
Truck: 14.067 @ 96.29, weighing in at over 7200#
Car (95 Cougar 4.6L V8): 14.680 @ 94.00

"The FIRST weapon is the mind, all others are incidental."
"I'd rather be judged by twelve than carried by six."
Reply With Quote
Old 10-19-2019, 07:04 PM
Mike L.'s Avatar
Mike L. Mike L. is online now
Got Sheep?
Join Date: Aug 2006
Location: Disneyland, CA
Posts: 15,258

I think you're right about the converter.
Inglewood Transmission Service
Shop 714 870 7300
Cell 310 918 9678

Tuned by Idaho Rob.
Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT -7. The time now is 08:44 AM.

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.