Got a question about my 01 Allison tranny.

At an idle, there's this 'whump' (best description) sound coming from what sounds like the bottom of the tranny.

It mimics the idle speed 'whump-whump-whump' and goes away above an idle.

Is this a cause for concern? Or is it an Ally thing?

Other than that the tranny performs flawless.

Got a question about my 01 Allison tranny.

At an idle, there's this 'whump' (best description) sound coming from what sounds like the bottom of the tranny.

It mimics the idle speed 'whump-whump-whump' and goes away above an idle.

Is this a cause for concern? Or is it an Ally thing?

Other than that the tranny performs flawless.

You really need to do a signature so we can tell what if anything you have done to your truck in the way of aftermarket modifications. I had a more of knock sound at idle, sounded like an exhaust pipe hitting a cross member of the frame. It turned out to be the bolts in the torque converter were getting a little loose and wobbling the holes in the flexplate. I would have it checked, it might also be the flexplate, these have been known to break. I know of nothing in an Allison that should make a whump-whump sound at idle. If your dealer says that is normal, go to a different dealer. Again hard to say without knowing more about your truck? Good Luck.

I'll check em, thanks.