Purchase a 2012 S550 W221 this past February with almost 70K miles. Rattles drive me crazy and that was exactly what was coming from the wood piece of trim located on the drivers door. A buzz or rattle that was emanating from wood trim on the door that would stop when you pressed on it ever so lightly. I researched this topic for some time on the internet. Shimming the trim with cardboard, bad motor mounts and loose attaching screws that attaches the strip to the door panel were all suggestions for cause and possible remedies to eliminate this noise. I had my door panel off three times. First I pushed tiny wedges in between the trim and the door panel with no success. Then I forced soft foam around the perimeter of the panel where the trim meets the door panel. This did not work either. I removed the door panel the one more time and made sure the fastening screws that attached the trim to the door panel were tight and I also pushed silicone between, and through the small slotted areas present on the black plastic at multiple location on the rear side of the trim. This also did not eliminate the noise. I was now determined to find the cause and how to eliminate this noise.
I purchase a used piece of trim from eBay to dissect. I found out that the trim was manufactured using three pieces. Wood trim, chrome piece epoxied to that and a black piece of plastic epoxied to that. I gently pried with small screw drivers starting at one end and was able to separate the three pieces that make up the trim. After 10 years of heating and cooling these three pieces I believe separated and created very small voids or tolerances which would vibrate at certain frequencies. This causes the rattle or buzzing noise that was eliminated by applying light pressure to the trim with your finger. Now that I knew how the trim was manufactured I remove the piece from my door. After separation I cleaned all pieces with solvent. You will not be able to remove pink colored epoxy so just leave it alone. Please be careful when removing your trim and remove the LED light strip from trim and lay safety on your door panel. You will need to remove the black electrical plug where it is attached to the panel but there is no need to disconnect the plug.Take the wood trim piece and apply silicon to the back of it. Again make sure you coat all of the surfaces. Now press the chrome strip onto the wood piece. Make sure all surfaces are covered with silicone. Next apply silicone to the chrome strip and press the remaining black pieces of plastic on to it. You want to apply blue painters tape to the finished side of wood trim and use some clamps to secure and cure over night. Reinstall LED strip into the bottom of wood trim with small little dabs of silicone. I did not want to apply too much silicone in case you need to remove the LED light strip in the future. Reinstall trim onto door panel and reinstall door panel. This repair may not be for the weak of heart, but this does eliminate the noise for good.

Jeff L.

 

Little late to the party, but what type of silicone did you use to re-seal everything? Considering adding some sound deadening to my door panels and I might as well do this while I'm at it. My wood trim pieces rattle, sometimes obnoxiously and I'd love to fix it.

 

I appreciate you exert some effort going thru trouble posting here about it .
Good job

 

Just a regular silicone caulk. I used one that drys clear but any silicone will do. Make sure you cover all contact surfaces between wood, black plastic and chrome components that make up this piece of door trim. Uncovered areas will have the tendency to resonate, which I believe make these pieces of trim to buzz.

 

Wow, also appreciate you detailing the process for us. Thanks.

 

The wood trim is not the whole story. If you're debating doing this, or have done it and it did not solve the issue, read on.

In my car, the subtle rattle was caused not by the wood trim, even though it stopped when I touched it gently, exactly as in the author's case. After a lot of trial and error, I disassembled all door panels, removed all wood trim, and reassembled. Surprise, rattle is still there. A few days passed by thinking what could cause a rattle. A lot more trial and error later led me to the rubber trim that sits on the bottom of the window opening, and has the door panel clip on it. This one has two sealing surfaces that the window glass slides against. Both those need to be covered with felt tape. Just two long strips of TESA tape, from end to end. Won't get into details, if you could get here I assume you will figure out the tape.

If you have not done the wood trim yet, save yourself some time and try this first. My doors are now dead silent, wood was never an issue.

 

What if it is the light strip inside the wood trim? You say it is the tape fix but what about if taking it apart and re-assembling it the light strip got in place so it is in bind between surfaces and can't rattle anymore making you think the tape fixed it?

 

Read my post again. Rattle was there with no trin in the dorr panels.

The light strip has a very particular way of fitting, hard to get wrong, it's also bent slightly more than the trim, so when mounted it's under pressure. Unlikely to rattle.

One thing to note - do not put anything on the light strip. No tape, no clear glue, ... It will absorb the light and kill your ambient lighting.