Real cause of leaking vapor barrier

[packrat555]

Upon investagation the real problem is not the vapor barrier but the water leaking in. It is a vapor barrier not a water barrier so it never made sense to me why it seemed normal to expect it to be blocking large amounts of water.

What I have found is the water is leaking in from the rear non-movable glass where the upright trim seperates it from the roll up glass. The water appears to be running straight down this trim but only on the fixed glass side which makes no sense. It is like every drop of water that hits this piece of glass winds up inside the door and because of the way it is "aimed" inside the door hits the vapor barrier.

It is not normal for any water to be running through the door. The vapor barrier and drains are meant to allow a few drops and moise air to escape.

Still working on a way to fix this problems in the mean time I have removed the rear carpet and expect it will take a week for the foam backing to entirely dry out.

[edjack]

The vapor barrier needs to be sealed against the door, all the way around, so any water running down will be directed to the drains in the bottom of the door.

[rf900rkw]

It is not normal for any water to be running through the door. The vapor barrier and drains are meant to allow a few drops and moise air to escape.

+1. The reason for the vapor barrier is to protect the door trim from humidity, not torrential floods. Sealing off the barrier to stop water ingress is a bandaid patch. The root problem is elsewhere.

[Desvio]

I replaced the seal on my vapor barrier, and it did absolutely NOTHING to stop the water from coming into the rear floors. But as with any car, the vapor barrier is designed to protect the door panel from moisture as car doors by design have water entering in them from the windows, and is supposed to drain out the bottom. But that's where the REAL problem with mine was found.

The difference with BMW is they use TWO door seals (inner and outer, plus a splash guard on the outer most edge), and the drains for the doors is between these two seals. Already noticing the door traps water between the two seals that conveniently nails my shoe when opened, I realized the water being trapped between the two seals had nowhere to go. The outer seal is against the body of the car, and a damn good seal too. But the inner seal is against trim, so when the water lever between the two seals rises above that level it starts leaking into the car. And it doesn't take much for the space between the two seals, and the door and body of the car to fill up with water.

I cut a small "u" shaped notch in the center of the outer seal (and I inverted the piece cut out, and glued it in to block the cut ends of the door seal) so the water between the seals had a place to drain out. Water no longer collects between the seals or falls out when opening the door because it now drains out, instead of collecting. I have been high-and-dry ever since, I have gone so far as running more water on the car than any rainstorm ever could, and it drains out instead of into the car.

The two seals is a great idea to reduce wind noise, but they seemed to overlook water building up between them.

Is this the same problem as everyone else? Dunno. But I would be happy to do a better writeup with pictures if anyone is interested.

[cnn]

Check the rubber seal between the door and the glass.

This Window Regulator DIY has some info on seals.
http://www.bimmerfest.com/forums/sho....php?p=6210803

...Is this the same problem as everyone else? Dunno. But I would be happy to do a better writeup with pictures if anyone is interested.

Some pictures would be great because I have no idea what you are talking about.

[cnn]

...Is this the same problem as everyone else? Dunno. But I would be happy to do a better writeup with pictures if anyone is interested.

Some pictures would be great because I have no idea what you are talking about.

[Desvio]

Some pictures would be great because I have no idea what you are talking about.

I'll see if I can get a clear picture this evening to post up.

[AnotherGeezer]

I replaced the seal on my vapor barrier, and it did absolutely NOTHING to stop the water from coming into the rear floors. But as with any car, the vapor barrier is designed to protect the door panel from moisture as car doors by design have water entering in them from the windows, and is supposed to drain out the bottom. But that's where the REAL problem with mine was found.

The difference with BMW is they use TWO door seals (inner and outer, plus a splash guard on the outer most edge), and the drains for the doors is between these two seals. Already noticing the door traps water between the two seals that conveniently nails my shoe when opened, I realized the water being trapped between the two seals had nowhere to go. The outer seal is against the body of the car, and a damn good seal too. But the inner seal is against trim, so when the water lever between the two seals rises above that level it starts leaking into the car. And it doesn't take much for the space between the two seals, and the door and body of the car to fill up with water.

I cut a small "u" shaped notch in the center of the outer seal (and I inverted the piece cut out, and glued it in to block the cut ends of the door seal) so the water between the seals had a place to drain out. Water no longer collects between the seals or falls out when opening the door because it now drains out, instead of collecting. I have been high-and-dry ever since, I have gone so far as running more water on the car than any rainstorm ever could, and it drains out instead of into the car.

The two seals is a great idea to reduce wind noise, but they seemed to overlook water building up between them.

Is this the same problem as everyone else? Dunno. But I would be happy to do a better writeup with pictures if anyone is interested.

I had been thinking this was my problem all along. I too get the wet shoe effect if I open either of my rear doors after going through the carwash and had considered notching the outer seal to see if the water would run out before filling the gap and then entering the cabin....once again filling the koi pond.

[pleiades]

Geezer, each door has small seam openings on the front and rear corners at the very bottom of the metal door frame, allowing the usually small (1 oz?) amount of trapped rainwater to drain out when the door is opened, or --apparently with my car-- if the car is pointed down an incline.

Randy, BMW seals the vapor barriers with butyl adhesive for a reason; the problem is that the adhesive eventually separates -- from the door frame or the VB or both -- with age.

I repaired my two rear doors (always leaked onto the sill but never into the car) using a fresh box of Windo-weld butyl cord. This worked great on the left door, but even the new adhesive continued to repeatedly separate along the rear lower edge on the right door. Before outright replacing the VB and/or using a permanent urethane sealant, I decided to try this stuff...

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

It is butyl-based so, it can be removed easily, sticks really well to everything including even the old layer of butyl adhesive, so no need to clean the old stuff off. My door has been leak-free for some time now with this, despite typical and sometimes atypically heavy NW rains this year. I keep waiting for it to fail, but it hasn't yet whereas with the typical butyl cord failure was just weeks away.

[dcmoore2]

I too had the rear seat pond issue.....I re-sealed the vapor barrier with automotive sealant. But after really thinking about it, it just didn't make sense that BMW designed their doors to allow water to get in in the first place. So I used black automotive RTV to seal the ends of the outer window seal (looks like a windshield wiper blade at the bottom of the window) that had shrunk over time and left gaps on each end. This keeps any water from getting into the door. Now, I have no pond or wet sills.

[Kevin Da Clean1]

.

[cnn]

...So I used black automotive RTV to seal the ends of the outer window seal (looks like a windshield wiper blade at the bottom of the window) that had shrunk over time and left gaps on each end. This keeps any water from getting into the door. Now, I have no pond or wet sills.

Bingo,

Just look at the pic above. Where the glass meets the door frame, there is a seal that looks like wiper blade.
Now look more carefully, you will see a small triangular gap where water can come in.
- I understand you can seal the gap between on the fixed glass (triangle glass)...
- But the roll-down glass, if you seal that small gap, make sure sealant does not stick to the glass.

[cnn]

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.

[tpatrik]

I have the same issue with my 2002 330i,,,can you post pics showing what you did?

[Qsilver7]

I have the same issue with my 2002 330i,,,can you post pics showing what you did?

As this is a MUCH discussed topic on just about every BMW forum where the model is no longer under warranty...a simple search using "BMW vapor barrier" should give you all the info you'd ever need on this topic. In fact, there are multiple videos on YouTube about how water enters/exits the interior of the door and how sealing the lower edge of the vapor barrier prevents water from getting diverted into the interior of the car...and keeps it flowing down to the bottom of the door where it exits thru the drain holes built into the bottom of the door.

Again, simple search here or google or any internet search engine using "BMW vapor barrier" should get you the images, DIYs, videos that can walk you thru this project.

Good luck. Give it a good internet search try...and if you can absolutely find NOTHING about this topic...post back and I'll do the search for you.

[keitho64]

I went for a cheap fix and ran a bead of clear caulk at the base of the fixed quarter window. That was over a year ago and it has been dry since. I found this topic while searching and I agree that the root cause if the problem is the window not vapor barrier.

[tpatrik]

Desvio,

Can you post some pics on how you cut the weather stripping? I know it is not my vapor barrier...i have taken them apart 3 times and they are intact and glued tight.

I believe the leak is coming from the rain channel above the door and filling up the space between the two door gaskets. I would really like to see a pic of the cut you made.

Thank you,

tpatrik

[dirtdevilnc]

I am having a similar issue on my e36 m3 on the rear drivers side door Leaking out of the bottom of the door onto my carpet
I cant seem to do anything to keep water from getting past the exterior weather seal despite having replaced it. It sounds like no water should technically make it past the exterior window seal correct and the barrier is just for vapor, not rain etc ?

[m5hoot]

I think there are differing opinions here on the root cause and the "best" cure, but they seem to all be correct to some extent. As the OP points out, the VB was never designed to hold-off a large attack. It is also likely true that to expect to not get a few ounces of water past the mechanical seals, especially as our cars get older, is probably not realistic. One camp wants to attack the root causes of the wiper blade seals and the vertical separator seals and not let any water get in and therefore essentially make the vapor barrier needless. Others accept that they can do the best they can at keeping water from getting in, but by keeping the weep holes flowing freely and the vapor barrier in good shape, they can withstand a pretty big attack without water in the foot well. Probably a combination of both approaches and removing the inside door panel so as to see what is actually happening to YOUR car. The good thing is that we can see what is occurring and then decide if shoring-up the second layer of defense can be made to overcome the age issues we all will face- You can bet BMW, by design, planned for water infiltration after the initial car owner is likely done with the car and has turned in the lease car or the richer crowd has moved-up to a newer model. The BMW engineers, I believe, were never told to make the BMW last forever such that there be no reason to trade it in. Just think about what it would have taken to make headlight adjusters last, radiator over-flows with 2 bar caps explode the system, any number of a thousand different plastic parts that must get brittle and fail, ABS unit that could use larger components as space is not critical, yet use finer-than-hair wires that won't take conventional solder and all but defy DIY repair, radiator fans that spin too fast eventually and go through the hood, et al.
BMW has no delight in seeing teenagers driving around in old BMWs, believe me. Solve your leak problem by the easiest manner practical for your car. There has been success in more than one method of repair for sure.

[fullthrottle540]

I have wet rear well. Will check barrier. Could this problem be caused by missing door sill??

[lesguy]

Could be part of s factor. But more likely it's vapor barrier as main factor

[RC Fresh]

Rear passenger floor is soaked since it started raining here in socal these past few days. Haven't check from where but hope it's just a reseal fix...

[Manny G.]

I've repaired (more like patched) my rear doors again last month for the 3rd time in 13 years. Just my luck, the rear window regulator stopped working and now I'll have to go tear it open again. I hate doing that, i never sticks the same again and I end up having to patch it again.

The last time I took to using 3m Window-Weld Ribbon Sealer, 3/8". It's thick and usually in stock at my local Advanced Auto Parts or Auto Zone. I really would like to see someone come up with a permanent solution to this. I noticed that there are large openings in the door that could use some kind of plate to block or deflect the rain away from the interior... water seems to wick off the white door latch cable and shoot its way straight at the vapor barrier.

[sealbeach740]

Although everyone has their own opinion on how to fix the wet rear seat carpet problems, I used Dow Corning 732 silicone sealant, and purchased the newer light grey vapor barriers for my 2003 540. I followed this thread, but there are a lot of threads out there on how to remove the door card & vapor barrier:
http://www.m5board.com/vbulletin/e39...iers-pics.html

My only note to add is to make sure you totally remove any old sealer/sealant used to hold the old vapor barrier down before you put the new vapor barrier in. Did this 2+ years ago & still no leaks & no wet carpet behind the front seats.
YMMV.

[maxjet]

Until the "entry point" of water is not addressed, it will always leak into the cabin when the vapor barrier detaches from seal degradation. Water enters from locations shown below (BMW seals here have gaps). My solution:

1. Restrict the entry point by applying black silicone sealant (I used RTV108) or equivalent. (Yes, for those that have 4K eyes, I ordered new quarter window seals, but problem will remain).
[IMG][/IMG]

[IMG][/IMG]

Sealing job not complete, but image below for illustrative purposes of where to add sealant. Place a piece of tape for the movable window before applying sealant.

[IMG][/IMG]

2. Re-Direct water away from barrier: I used a standard 8.5 x 11 plastic sheet protector, cut a small hole at an approximate area where the door handle cable will feed thru. Then get some of that remaining sticky bmw vapor barrier sealant and use it to place the plastic sheet underneath the door. This will re-direct water away from the barrier. I also used some sealant around the hole where the cable feeds thru the plastic sheet. (Note, make sure the plastic protector opening faces down!)

[IMG][/IMG]

...at the end it should look like this:

[IMG][/IMG]

3. Re-apply sealant and install vapor barrier: Remove any non-sticky sealant and re-apply new sealant. Install Vapor Barrier, reinstall door panel as required.

Total Cost: Under $1.00 for plastic sheet protector (any plastic cut to size will also do) plus cost of sealant. Labor: under 30 mins for each door).

Cheers!