Hey everyone, new to this forum. I have a 2019 GLC 300 4Matic with 20k miles. I keep hearing a faint marble in a can noise at slow speeds coming from what I believe the cargo area or around there. Has anyone experienced this and know what it could be? Driving me crazy!

 

Try emptying trunk, including tools, air pump, etc including horizontal privacy blind and trunk solid cover.
We found noise was coming from inside privacy blind. Dealer could not locate, they even replaced a rear shocker!!
let us know how you solve it.

 

Mine is 2018 GLC300. Multiple attempts and still haven’t found where it is coming from. Extremely annoying buzzing noise coming somewhere in the back. Not the seat latch mechanism as I have checked it already. Also not the cover as I have already removed it.

 

My wife complained about a marble rolling noise coming from the front passenger door. I popped the interior door card loose from the clips using a trim tool and a little white spherical plastic bead/bearing/marble fell to the ground.
Sound is gone, but I have no clue what the thing that fell out is. I kept it so I have it in the event it's important. Also no clue how this seemingly foreign item got into the door.

 

found it.. Top of the side panel where it meets the glass. This is in the luggage area.


(Random photo for illustration purposes)

 

So what caused the rattle? Something in there, or a poorly installed trim piece?

 

My guess is overloading cargo area creates pressure on the panel causing the clips to move out of its original position. Half of the the foam tape inside was sagging. I've just reapplied the foam tape and reseated it back.

 

Update to my original post.

The rattle still continued after doing the work I've mentioned above, so I've decided to completely remove the panel. This time I have pinpointed the source of the noise; it is the seat belt mechanism (only the rear passenger side).

Some older models (W204?) had the same issue where the metal ball making the noise in the mechanism, and it is the same exact issue. There is a socket on the seatbelt mechanism, and I did not want to unplug it as I do not know what it is for.

For that reason, I was not able to disassemble the mechanism, but instead I've wrapped it with some noise insulation material. It is now much better, but I still hear it faintly and rarely. I think I will get to work again and disassemble it without removing the socket and put some light oil on the casing for that metal ball. This car is so quite inside that I cannot stand any noise, even if it is a very minor one.

 

Hi All. I got my rattle better by doing this. I have no doubt that mine is caused by the tailgate. I have heard that some guys speak of re-alignment. Also, my rear-view camera is noisy when it engages or opens (2018 GLC Coupe. It sits under the boot handle, which opens). Just sounds too noisy for something Merc would do.