Hello all. I have been a Cadillac tech for many years. Usually drive Dodge trucks ( easy on the flaming ) I just bought a 2001 GMC 2500 with the 8.1 and have a possible problem. The tranny whines considerably at idle and in the lower gears. I have been told that this is normal, but I figure you gurus here could confirm/deny such a claim. Thanks in advance for the help!


nogood o~`o

Welcome!,

The Allison is not a quiet transmission by any means (at least not thru 2005 MY). That being said, the Allison sometimes makes an extra loud whine when cold in first & second gears. Doesn't happen all the time but when it does, it's only when it's cold and after a few miles it back to the normal whine. Doesn't seem to hurt anything. I believe the gears were helically cut in MY2006 to make the trans. a little quieter, but I've heard those helically cut gears are not quite as strong as the straight cuts ones that we have. (I'm really out of my league here).

Not much help. All you can really do is compare the sound to someone else's 8.1L.

DEWFPO

My trans is a little loud. Its louder tan my buddies dodges and my old 4L80E. (this is normal.)

That's normal for a 2001 Allison. The pump is noisy at idle and the gear whine can be obnoxious in the first few ranges. It's more noticable on the 8.1L because the engine runs quieter and doesn't mask the sound like the diesel. Annoying but not harmful.

DEWFPO: The Allison gears have always been helical, they just changed the profile in MY06 to make them quieter. They can still handle the same amount of torque.

Sorry, we didnt mean to shut this thread down, our mistake, clicked the wrong button :o:

Thanks for the replies. I was fairly sure that the noise I hear was normal, but it never hurts to get a second and third ( or fourth for that matter ) opinion. Looking forward to many trouble-free miles....

nogood o~`o