Loud metallic rattle from behind rear driver side seat back

[bdmd5093]

I have a 2018 Silverado LT 4wd all star edition crew cab short box purchased new in December and now has about 4500 miles on it.

 

Any time I drive over rough road (pavement, crush and run gravel, dirt) it produces a loud staccato medium pitched metallic rattle that is coming from behind the rear driver side seat back.  It only does it if the rear seat is down, not if folded up.  When parked I can bang on the seat back with my fist near the upper corner closest to the door and reproduce the sound.  I don’t recall it doing this initially but seems to either be getting worse or either I am just more sensitive to it.  

 

Has anyone else experienced this and if so what was your fix?  Should I just take it to the dealer?

 

I thought about wedging a piece of dense foam back ther but not sure if it would interfere with raising the rear seat, because when you do lift it up the seat back slides up vertically some too.  I haven’t figured out how to remove the seat back yet.

 

thanks!

brian

[UrbanRage]

I have the same sound and it is from the passenger side rear seat. I've looked at the seat bolts and seatbelt bolts. It does it when the seat is up and down, but it is louder when the seat is down. It's driving my fkin crazy. Once I have the time, I plan on having my wife drive while I'm in the back seat.   

[Sierra Boy]

Did you happen to use the jack handle or take it out for some reason that is under the rear seat? They are fun to put back together just right, so they don't rattle.

 

Sierra Boy

[3tspapat]

I've had the same if not similar sound as you all described. Was able to reproduce when I banged on the rear seats hard, but not matter what I tried to tighten, I could not get the sound to go away nor identify the exact source. Then noticed that it didn't do it when the rear sliding glass was open. Started to mess with it and discovered that it only does it when the rear glass is fully closed. I guess it was making the noise because the cable that pulls the window does not have as much tension in it when it's fully closed vs. when it's fully opened or when it's anywhere in between. 

 

 

[MBSierra17]

There is a small metal piece in the hinge that when the seat back is fully upright, helps to quasi lock it in place. I believe mine may be the source of the rattle you are describing. Rear seat, kind of under it. 

 

I noticed this because when it very cold, if I raise the rear seat on that side, it can get stuck in the upright, and I have to reach under to manually disengage the mechanism. I think mine is loose, and causing both the extreme cold problem, and the rattle when the seat is down. Thinking about taking it to the dealer to investigate soon. 

[1fast ss]

I am experiencing the same sound. When I push down on the seat I can reproduce the sound.

[Sierra Dan]

There is a thread or two regarding this noise issue dating back to the new K2 models in '14

Something about a bracket or a plastic clip that comes loose and causes metal to metal clanging.

This might be your issue. Just search for rear seat noise or rear seat rattle.