makeinu0

Hi, my first thread here.
My vehicle (2012 C250)'s parcel shelf has been vibrating while driving.

I've done some research, and while is seems to be a common problem, some got lucky at the dealership and others didn't. The easy fix, according to a few members here, is stuffing a rubber foam up the holes found in trunk.

https://mbworld.org/forums/c-class-w...vibration.html

https://mbworld.org/forums/c-class-w...e-my-c300.html

My question is, what size rubber foam do I use, and how should I install it?
If anyone here fixed similar issues with DIY using rubber foam through the trunk, please chime in.

Thanks in advance.

makeinu0

well since I had no luck in advice, I decided to use a flat foam about 4 inches in thickness, and stuffed as much of it I could from the trunk holes. I also inserted some between the parcel shelf and the glass/rear panels. Fair amount of noise reduction from these, but I could still hear the "cracking" and "clicking" noise resulting from the plastics expanding in heat (I live in Hawaii).

Decided to bring in the vehicle to dealership and have them take a look at it. I searched through a Japanese forum (I'm from Japan, originally) and learned that the noise is most likely coming from the third brake light. I know that the dealer will not be replacing the brake lights for such minor "noise" issue, but its well worth a shot to have them take everything apart and put it back. I might even ask them to "professionally" insert the foams while they're at it.

Will post result, if any.

Knightmare69

Yea, there wasn't really a DIY on this subject and most ppl I think tend to just turn up the stereo or live with it. I've been meaning to look at mine as mine not only creaks but flexs sometimes during turns. It's annoying and from my past experience with the local dealer I doubt they'll help so I'll have to figure something out. Look forward to how you resolve yours.

makeinu0

So far, as mentioned above, the corner and lining stuffing of foams really decreased the noise. I too experienced the same "flex" at times when turning corners, and this also significantly decreased with enough foams on the corners (gotta squeeze enough so that you literally can no longer move the shelf by pushing it).

I guess the only other option I have is to tint the rear window with one of those heat reduction ceramics, since I know for a fact that this noise is caused by temperature change.

makeinu0

Update

Brought the vehicle in to dealer on 7/18
Pointed out the noise, but was not able to replicate at the scene since it stopped on the way to the dealer (probably fully expanded from heat at that point)

Told dealer that I stuffed foams in the shelf, was informed that its best to keep it untouched as the mechanics may void the claim if foreign objects found.

Asked if the dealer (the only dealership in Hawaii, covering all islands) ever had similar claims, was told
that its never been brought to their attention.

Knightmare69

Dealers would have to prove that whatever modification you made actually affects the car as a whole and said part in order to void your warranty. Luckily Hawaii as far as I know should fall under MBUSA so worse case you can file a complaint with them if it ever comes to that. I'm stuck in Hong Kong where it's a licensed franchise so they can opt not to follow MB rules.

makeinu0

Knightmare69, damn that sucks. But Hawaii isn't much different as we're stuck on this island, so its pretty much a monopoly and MB Hawaii could sometimes be a total dick. Actually, most luxury auto dealership on the rock is full of **** most of the time (a friend purchased new GS350h from Lexus, on the first service lexus damaged his vehicle and asked if they could use his insurance and pay him the deductible. He immediately sold the car and went to Nissan).
Yes, we could complain to the HQ but that also means I have to fight for my right at the dealership until my warranty is up.... sucks, but this is the reality here.

Anyways, the dealer called to let me know that they weren't able to replicate the issue (as expected). They also took out the foam so I would have to put it back
They said they will try it again tomorrow morning, but I actually heard the same cracking noise in my loaner car, so I'm thinking they won't be able to fix it.

makeinu0

Update

I drove around with the tech, he confirmed the noise and said they will insert felt around the shelf/plastic and see if that helps with the noise. On top of that, I will also re-insert the foam on both sides just to apply pressure on the shelf.

If that still doesn't help I will tint the window to reduce heat.

makeinu0

Update

Picked up the car, so far I hear no noise from the rear.
I will see how far it goes without the noise returning.

I haven't inserted the foam on both sides just yet, since I will need to return to the dealership for something else and want to leave it untouched if the noise returns before the appointment.

Knightmare69

Why does the felt work and not the foam? The way your tech put it makes me feel like the shelf was made too small for that area if they need to add extra felt around the edges. I got a rear strut bar, gonna see if stiffening the chassis prevent the shelf from flexing as much thus reducing the noise.

makeinu0

Knightmare69

Not sure, but after reading thru different threads with similar issues, I find that this felt technique is the only thing MB technicians got at the moment (And I haven't read a single thread saying that the felt fixed it).

It may that the size is fine, but the expanding plastic keeps rubbing against either on each other or the glass, making that irritating etching noise.

The stiffeing sounds like a good idea.

makeinu0

Update

drove around today and as the sun started to heat the dash/parcel shelf, cracking noise returned.

Knightmare69

That sucks, back to installing the foam I guess.

makeinu0

Yea, I stuffed some foam around the shelf. I'm just gonna go with hardcore heat shutting tint for the rear. I am positive that heat is causing it, so hopefully that ends it.

Really? I stuffed A LOT of foams around the corner and lining of the parcel shelf (I was actually surprised by the amount when the techs pulled it out and left it in my trunk..... I added little by little every damn time it creaked)