Sierra popping sound in rear end/rear suspension when truck flexes.

jbr1888 · July 9, 2020

I have had my truck (SLT X31 CCSB 6.2) since November, and for a while I've been noticing a popping sound coming from behind the cab, can't really tell which side, when I drive over dips or bumps on the diagonal. It seems worse in reverse. My driveway meets the road in a way that means every time I leave, I turn and drive through the valley where the road and driveway meet at basically a 45 degree angle. This causes the truck to flex slightly and that's when the popping happens. Its loud enough to hear inside the cab, but its not super loud. For a while I assumed it was stuff rolling around in the bed, that's kind of what it sounds like.

Anyone else have anything like this going on?

TimberPimp · July 10, 2020

8 hours ago, jbr1888 said:

I have had my truck (SLT X31 CCSB 6.2) since November, and for a while I've been noticing a popping sound coming from behind the cab, can't really tell which side, when I drive over dips or bumps on the diagonal. It seems worse in reverse. My driveway meets the road in a way that means every time I leave, I turn and drive through the valley where the road and driveway meet at basically a 45 degree angle. This causes the truck to flex slightly and that's when the popping happens. Its loud enough to hear inside the cab, but its not super loud. For a while I assumed it was stuff rolling around in the bed, that's kind of what it sounds like.

Anyone else have anything like this going on?

Same thing is happening to me. Idk what the deal is but my 2019 X31 does it as well. I've asked the dealer to figure it out but they've found nothing.

Silverado4x4 · July 10, 2020

19 hours ago, jbr1888 said:

I have had my truck (SLT X31 CCSB 6.2) since November, and for a while I've been noticing a popping sound coming from behind the cab, can't really tell which side, when I drive over dips or bumps on the diagonal. It seems worse in reverse. My driveway meets the road in a way that means every time I leave, I turn and drive through the valley where the road and driveway meet at basically a 45 degree angle. This causes the truck to flex slightly and that's when the popping happens. Its loud enough to hear inside the cab, but its not super loud. For a while I assumed it was stuff rolling around in the bed, that's kind of what it sounds like.

Anyone else have anything like this going on?

Check your rear axle U bolts there have been reports that they are not torqued down tight and making this popping sound.

Here is the thread. https://www.gm-trucks.com/forums/topic/237626-u-bolts-loose-might-want-to-check-yours/?tab=comments#comment-2404086

Edited July 10, 2020 by Silverado4x4

Silverado4x4 · July 10, 2020

N/A

Edited July 10, 2020 by Silverado4x4

chadman · July 10, 2020

I can tell you generically we see this a lot with all kinds of trucks that have rear leaf springs. As mentioned, re torque the u bolt nuts. If you don't have a torque wrench, arc them about a quarter of turn.

kpanza · July 10, 2020

5 hours ago, Silverado4x4 said:

Check your rear axle U bolts there have been reports that they are not torqued down tight and making this popping sound.

Here is the thread. https://www.gm-trucks.com/forums/topic/237626-u-bolts-loose-might-want-to-check-yours/?tab=comments#comment-2404086

I was the guy who started that post referenced above, and like you, I have the "bowling ball rolling around bed" noise in exact same scenarios! Anytime radio is off, it's constantly making the noise. I found that my u-bolts were very loose, but even after tightening them, it's still the same. There have been other posts about having different rubber/plastic isolators put in between the leaves, TSB 19-NA-129. I have yet to go back to the dealer for this supposed fix, as my truck was in the service center for 65 days getting the transmission fixed...so I am shying away from having it parked there again! But the sound drives me nuts, sounds like my '73 K5!