Re-sealed your door vapor barrier but it still leaks?

Well, that was my situation. Shortly after buying my 528i in summer 2010 I went through the routine of re-sealing the VBs on the two rear doors -- both had separated from the door frame, presumably because the old butyl adhesive had lost its tack.

I used the 3M Windo-weld butyl cord that is recommended on these forums. This worked great on the left door and has held up but on the right door, it continued to lose the seal along the rear lower edge, straight down from the airbag. I probably went through the drill four times, using fresh 3M cord each time, but the repair probably never lasted more than a few weeks at a time. Fortunately even when leaking, the water didn't ever get past the door sills so yeah, I haven't felt pressured for a fast fix but this did get annoying.

Before buying a new VB and more Windo-weld or possibly a permanent urethane sealant, I decided to try one other product. DAP 18188 Butyl-Flex Gutter & Flashing Sealant.

http://www.dap.com/product_details.aspx?product_id=19

Hardware stores carry it, as does Amazon, for a few bucks.

It is softer right out of the tube and of course needs a day to cure, but retains its tack and best of all, sticks well to surfaces already saturated with old butyl adhesive .... meaning no need to go crazy cleaning off the old stuff. Of course, if you've not used stuff like this out of tube, you might want to practice on something and get a feel for the way it flows before trying it out on your car.

So far my annoying right door has been watertight for a couple months now, despite some unusually heavy rains. Thought I'd throw this out here in case anyone else might want to give it a shot before opting for something more drastic.

good to know

I used 3M Window weld as well. However, after I applied the tape to the door, I waved a heat gun on the low setting to softened the butyl tape to a sticky goo, applied the vapor barrier then used a Dynmat style roller to press the barrier to the tape. 5 years later, still no issues. Even through a hurricane and the 2nd wettest year ever recorded in history for 2011 with no puddles in the back seat since.

In fact, last year when I removed the vapor barrier to tap out a ding, I had to use a heat gun again in order to remove the vapor barrier.

So, it is important to heat up the butyl tape AND press it with a roller while it is still soft and you shouldn't have any issues.

I used a heat gun with the 3M as well. I cleaned the VB and door frame surfaces of old butyl (using Ronsonol lighter fluid = naphtha). As I stated, worked well and is still holding great on the left door, but this procedure failed multiple times on the right.

Whatever works for ya, the 3M didn't work with my right door but the DAP is working great, requires -no heating- and -no pre-cleaning-.

I'll probably try this DAP next.

What if you were to use permanent silicon for the bottom half to stop the leaks forever, but use 3M/DAP for the top half in case of a window regulator job etc.

problem is the amount of water leaking into the door. It is a vapor barrier not water barrier.

What I found was water is leaking in from the rear quarter window in the corner where it meets the trim that seperates it from the roll up window. Why a fixed would would not we water tight doesn;t make sense. Not a drop come through on the roll up window side. Test for yourself to verify.

I am still trying to find a diy to remove this glass piece and reseal it. Even called around the bmw dealers and they think the solution is to seal the vapor barrier.

Originally Posted by Packrat555

problem is the amount of water leaking into the door. It is a vapor barrier not water barrier.

What I found was water is leaking in from the rear quarter window in the corner where it meets the trim that seperates it from the roll up window. Why a fixed would would not we water tight doesn;t make sense. Not a drop come through on the roll up window side. Test for yourself to verify.

I am still trying to find a diy to remove this glass piece and reseal it. Even called around the bmw dealers and they think the solution is to seal the vapor barrier.

I think part of the problem you have is one of semantics. Other carmakers call these things water barriers. BMW actually uses the term foam insulation because on the e39 the VB does double duty in shutting out noise. There are no "vapors" inside the doors anyway.

The window seals on these doors aren't watertight. I don't know for sure but I'd guess they're not watertight on any make. Water hitting the closed windows probably does collect and enter the inside of the door in the spot you mentioned. On my doors that spot has about a 2 mm open gap at the bottom, so I'd expect rainwater to be dripping in from there.

BMW used butyl adhesive to seal the VB all the way around and my bet is, they did that to prevent rainwater from leaking out and under the door panels. But on a lot of these cars, that butyl seal separates along the bottom rear corner. My impression is that BMW picked the wrong sealant or that age is taking its toll. But I can only speak for the situation on my car. My doors don't let in a flood of water. When I open them after a rain, only an ounce or two drips out the bottom corners of the door frames.

Originally Posted by smmr

I'll probably try this DAP next.

What if you were to use permanent silicon for the bottom half to stop the leaks forever, but use 3M/DAP for the top half in case of a window regulator job etc.

I've had the same thought in the past but decided it might not be a good idea if I later wanted to replace the VBs outright.

Originally Posted by Packrat555

problem is the amount of water leaking into the door. It is a vapor barrier not water barrier.

What I found was water is leaking in from the rear quarter window in the corner where it meets the trim that separates it from the roll up window.

Sounds about right. I fixed my vapor barrier as well in the rear driver's side door but the leak came back about three weeks later. I put some electrical tape along the outside of the window trim from the front of the main window to the back of the quarter window as a temporary solution. Even though the main window was rolled down and up a couple of times, compromising the tape seal at that window, the quarter window tape was intact. I noticed no water inside the door or on the floor even after wet snow had settled on the car overnight since.

I'll be checking into it in more depth soon, I hope.

My dealership fixed my leak for about $1600. It hasn't leaked since, ha ha.

This morning it rains slightly here, so I sit inside the car and watched the rain droplets on all 4 door roll-up glasses....
The droplets run down and runs between the "wiper blade" and the glass, so it definitely enters the inside of the door.
This is a design for many cars, the seal between the "wiper blade" and the glass is good but NOT water tight.

During a torrential rain, then some water enters the inside and some flows out.

You can always do a quick test, open the door a few inches.
- Get a spray bottle and spray the glass from the outside.
- Make sure the chrome trim is dry (i.e. don't spray the chrome trim)
- Watch how water droplets come down.
- You will see that some water will enter the the space between "wiper blade" and the glass
(i.e. the chrome trim will stay dry)
- Now, you should see water coming out of the bottom drain holes.
- Now pour a cup of water down, you will see that excess water will overflow onto the chrome trim.

The bottom line:
1- Re-sealing the VB is important.
2- Make sure the drain holes at the bottom of the door are not clogged. I use a BBQ skewer (made from bamboo, you can get a whole package of 100 for $2 at grocery store) and probe the holes.

Another way to understand this design (actually this is true for virtually all cars out there)...

1. During the VB resealing job, leave the VB out for a few minutes
2. With window all the way up and tight, leave the door open, now use a water spray bottle and spray from the outsdie.
3. You will see small amount of water enters the space between the "wiper blade" and the glass.
Now look from inside, you will see water dripping down at the bottom of the glass into the inside of the door.
Now, water should come out of the drain holes, if not poke the drain holes.

Anyone who's done this, how are things holding up for you? I'm about to do this a second time and really want it to be the last...

well, you learn something new every day...
I just did my passenger side rear door vapor barrier again and guess what? It's still leaking.
I used some tips I found on here, about cleaning the door skin with mineral spirits, using a heat gun to make the butyl tape more tacky, pressing down very hard around the perimeter to ensure a good seal; I even used duct tape to further seal the vapor barrier. But it failed. Well, not exactly. I looked around the whole door only to find that the vapor barrier did adhere and was not leaking because of all the steps I mentioned above. To make sure of this, I opened the door and poured a bucket full of water onto the glass. I was immediately able to identify the problem. Water was leaking through the two holes in the door where the plastic push clips (not sure what to call these, related question below) from the door panel "pop" into. See pic:


After the repair, I just put on the the door panel, figuring that the vapor barrier problem was fixed. When I removed it and saw where the water was leaking, I knew it was my fault because I did not replace the "plastic push clip" that I had broken the first time I did this repair. Having not replaced it, water was getting in through the hole. See pic:


I wonder if this was the source of my leak all along after the first "repair?" Should I get another one of these or just block up the hole? The door panel stays on fine, so I wonder if I could just cover or caulk it to keep the water out? I searched the forums and don't recall seeing anything in regard to these "clip" holes leaking...

OK, so what is this plastic "clip" really called? I checked Real OEM and the part is shown in the diagram as #2, but it is not in the parts list.
http://realoem.com/bmw/showparts.do?...51&fg=50&hl=15

Also, note that the butyl tape is shown in the diagram as #17 and neither is it in the parts list.
Can anyone help identify these part names/numbers?



Related to this DIY project: This is the product (purchased at Auto Zone ~$15) I used today:

http://www.autozone.com/autozone/acc...er=501842_0_0_

Update: I put some of the butyl tape into the two holes in question, tested with a bucket of water, and there is no water infiltration. The door drain holes are working properly and no leaks under the door panel.
Now, time to go out and do the other side AGAIN.
One good thing, I can get the door panels off and on very quickly.

See also:
Sealant for door panel vapor barriers (1) & sizes for the adhesive (1)