Fixed your leaking vapor barrier? Don't forget to lift the carpet.

BMW uses a high-density foam backing that is bonded to the E39 carpet. It's a great noise insulator, but it also acts as a giant diaper when the vapor barriers leak.

So, if your rear carpet feels damp to the touch, it's actually saturated with a shocking amount of water that is held within the foam.

Once water gets absorbed into the foam, it's impossible to dry without lifting the carpet.

There are several bundles of electrical wires under the carpet, so I think it's beneficial to thoroughly dry the foam backing.

Start by removing the back seat. Then the rocker trim. It uses a 10mm bolt with 2 push-in fasteners (be gentle.. this piece is brittle)

Then I popped off the bottom of the B pillar cover. This allows the carpet to be folded back and lifted up.

I've spent over 2 weeks placing absorbent ShamWow towels (made in Germany. You know the Germans make good stuff) under the carpet overnight, wringing the excess water, letting the towels dry, and repeating the process again and again.

I've pulled out so much water that it makes me wonder how many electrical problems could be attributed to wet carpets.

I think you are right, mine leak and are on my list to fix. I put a piece of aluminum foil on the door jam so it extends inside 3" and under the door 3" then close. I have towels on the floor and they dont appear to get wet any more. I put a dehumidifier in my car overnight on high and in the AM, things are pretty dried out inside... now I need to jump on these, driving me crazy. Did you use the weatherstrip "bead" or 3M Weatherstrip Adhesive (Yellow) approach?

I purchased a roll of Butyl adhesive (that's what the factory uses) from a local auto body supply company. It sticks like crazy on the door, but I had issues getting a secure bond on some smaller areas of the vapor barrier. I think that the process of removing the barrier, and the old Butyl, slightly delaminated the surface of the barrier. If I ever need to do this again, I'll order new vapor barriers (about $35 each) to insure clean bonding surface.

PS: A quick way to check your vapor barrier is to remove the Puddle Light and stick your finger inside. The panel will be wet in that location if the barrier is leaking.

Originally Posted by Johnny Canada

I purchased a roll of Butyl adhesive (that's what the factory uses) from a local auto body supply company. It sticks like crazy on the door, but I had issues getting a secure bond on some smaller areas of the vapor barrier. I think that the process of removing the barrier, and the old Butyl, slightly delaminated the surface of the barrier. If I ever need to do this again, I'll order new vapor barriers (about $35 each) to insure clean bonding surface.

PS: A quick way to check your vapor barrier is to remove the Puddle Light and stick your finger inside. The panel will be wet in that location if the barrier is leaking.

For $35@ probably not a bad idea, do it once, do it right, never do it again. I'm thinking of picking up the BSW stage 1 speaker upgrade kit as well and swap out the stereo speakers at the same time... again, dont want to open up the door again while I have the car (the PO replaced both rear window regulators, hence why I suspect they leak).

Two things:

1. The Vapor Barrier: I think you can use any thick plastic barrier at hardware store. This is the same stuff people lay on the basement gravel before pouring concrete floor. Make sure you get the thicker plastic type.

2. The butyl roll: I got a roll from a local Auto Glass Repair shop: 15-foot roll for $15.
The roll is the same size as the pencil (about 3/16" in diameter). Go to any local Auto Glass Repair shop and ask for it. This butyl stuff was used in American cars from 1970s and 1980s Chevy etc. It looks like this:

wowwww..great advice on the vapor barrier,i had the same problem...now i will try this...i will let you guys know how it came out.......2002 530i......

I usually take the carpet completely out, pressure wash it to remove the odor, and dry it in a paint booth oven. Always works like a charm.

The E46 crowd is having trouble finding the right sealant according to this post today:

Originally Posted by computerwhiz1

I have redone all 4 doors vapor barrier seals twice now. I used the 3M window-weld in a roll which is exactly what the dealership told me to use. Apparently its what they use to do the job as well. The first time I redid the seals they leaked and I assumed that it was because I hadn't pressed down hard enough to obtain a good seal. So this most recent time I used a small paint roller to roll over the fresh bead of window-weld on each door to be sure that I got a good seal. I checked each of the vapor barriers right after resealing them and all of the seals looked good and held when I tugged on them even moderately. I thought that surely I had solved the problem. Not so! The doors have now leaked again, all four of them. It has rained here in the south-east for about the past 7 days straight so I have some pretty soggy floor boards on all four corners. I am going to reseal them again this weekend using silicone sealant as I am about 99% sure it will work. I will just loose the ability to simply pull the vapor barrier off if I need to get under it at a later date. Does anyone have any other suggestions as to what to use before I use the silicone sealant? I am sure it is the vapor barriers as I have taken the door panels off and watched the water run out from behind the vapor barrier and into the car where the vapor barrier has pulled away from the bottom part of the door.

Anyone tried this:



I heard really good things about it. Seems like the windows shop have it. (3M 08609) I also found it on Amazon

Why not just use regular old silicone caulking?

Originally Posted by bluebee

The E46 crowd is having trouble finding the right sealant according to this post today:

I did mine a couple years ago and found out recently that both doors are leaking again. I used the 3M window weld last time and wondered about trying something else this time, like this...

Originally Posted by doru

Anyone tried this:



I heard really good things about it. Seems like the windows shop have it. (3M 08609) I also found it on Amazon

I wonder if this creates a more permanent bond? I'm heading out to Auto Zone to check that out or buy the window weld.

Originally Posted by Topaz540i

Why not just use regular old silicone caulking?

Silicone makes a more permanent bond and you want to avoid that in order to reuse the vapor barrier.