[jh_f30]

I'm in the middle of resealing the vapor barrier/sound insulation panel on the left (driver's side) rear door. After the last rain storm we had, I noticed the floor behind the driver's seat was pretty soaked. I thought maybe it was a clogged drainage passageway and blew compressed air through wherever I could. However, subsequent car washes would result in more water leakage. After some research, I learned that it might be the vapor barrier in the door. So today I finally decided to tackle it.

Ordered some butyl tape, and took the door card off. Pretty straight forward, but the clips are fairly robust so it can be a little nerve-wracking. Inspected the barrier, and sure enough, it was almost completely unsealed along the bottom edge. Carefully pulled it off, using a utility knife to cut the butyl tape that was still holding strong. So far, the hardest part has been removing the old butyl. From the door itself, I found that getting it started at an arbitrary point, balling up the butyl and pulling quickly away from the door works pretty well. Comes off clean, minus a slight line at the edges. The butyl stuck to the vapor barrier is a little trickier because it's basically a foam material and is prone to ripping, so I took my time with it.

Cleaned up the area and am about to start the resealing process. Also, I found that there's a magic marker outline of where the butyl tape should be applied, so that makes it easier. Watch out for the little black gaskets around the clip points. Most of mine stayed on the door, but a few fell off while I was wiping away the remaining residue. I just hit the backs with a tiny bit of spray contact adhesive and stuck them back on. Apparently, they're another potential point of water ingress.

After I'm done, I'll give the car a good spray down and see if that does the trick in getting rid of the leak. Guess it'll call it a maintenance wash, even though my car hasn't gotten too dirty after my last wash. In any case, definitely want to have the leak buttoned up before any rain come autumn/winter.

[im_an_alien]

I had this problem back in the day with a 2002 e46! Unbelievable BMW still hasn't got it right, it's a well known issue. Good work there...

[jh_f30]

UPDATE

Vapor barrier resealed, door card reinstalled, 10 minute "torture test" with my hose and a sprayer on and around the door, no more leaks!

[zeikei]

My previous F30 had a leak in front door that kept puzzling me, I have resealed the vapor barrier in several bimmers that I have owned but this time there were no obvious bad spots in the barrier. I resealed it anyway and thought it was done, some days later after rain again some leakage. Could not reproduce at will.

What I finally realized after quickly disassembling it after a leak and seeing where it was wet that it was leaking from the loudspeaker. Since F30 has the speakers mounted to the door itself and not the door panel the backside of the speaker is in the wet zone. I am still not 100% sure if it was from the holes for the speaker screws or the speaker itself but I sealed both and it fixed it.

I also then realized what had made the leak "slow" and not easy to reproduce quickly was because the vapor barrier has a U shape under the speaker, your pic of door shows some in rear door as well. Due to that shape and the butyl not being applied all the way to the edge of the barrier creates a small container for the water to collect before it starts to drip all the way to the bottom of the door.

[Trimrol]

That's what we can report.
https://f30.bimmerpost.com/forums/sh...0&postcount=17

[Fliplegend]

Originally Posted by im_an_alien

I had this problem back in the day with a 2002 e46! Unbelievable BMW still hasn't got it right, it's a well known issue. Good work there...

This is the company that is STILL using plastic for critical cooling parts. I'm pretty sure they have doubled down on using MORE plastic.