Popping noise in drivers floor

[Dan P.]

I just got a new to me 2011 2500HD duramax with 99k miles on it. Just here recently every time I put the truck in park and it rolls until the transmission catches I hear a pretty loud popping sound from somewhere under the dash in the floor of the drivers seat. Everything works fine as far as I can tell, and I’m fairly certain it’s inside the truck. I can feel it in the brake pedal and sometimes I think I can in the steering wheel. It doesn’t do it in a turn or anytime the truck is moving in drive or reverse. Only does it when put in park and let go of the brake. I have no clue what it is. Thanks!

[riverbanks]

First try, shutting it off in neutral,sound gone? check tranny mount and motor mounts for movement?

[sefiroxx]

Using the transmission to park? Get ready to save up for a new one , parking pawl can break under too much stress. Fix the parking brake and see if the sound goes away. If so, then tranny mount or parking pawl.

[Dan P.]

I am parked on level ground in my garage. It only makes the noise when it rolls forward or backward as I release the brake when in park. I shut it off in neutral and no noise, but it didn’t have the slight “catch” as it does when in park. I will check tranny mounts. 

[riverbanks]

Hmm,parking pawl?stuck?slow? binding?what about a additive for tranny,boost the lube?

[barry G]

there is the driver side cab mount forward, sometimes they put a shim there thinking ahead for column weight. My 96 did not need it on new poly mounts.

2011 is quite young for weird noises.

[Dan P.]

I’m positive the noise is coming from under the drivers dash. It is not loud at all outside. In fact can’t hardly hear it at all. It is loud from under dash down where the pedals are. I’ve called the dealership and talked to the transmission guy there and he’s never heard of it. They are going to research and get back with me. It does only make the noise when the parking paw catches. But is inside in the cab. I’m lost for ideas.