Troubleshooting rear footwells soaked with water? - The Unofficial BMW M5 Messageboard (m5board.com)

Vason · 23rd June 2007, 05:08

So here is the problem. My car is always garaged at work and at home so it rarely sees bad weather. I was out of town for two weeks and my car was outside the entire time. A huge thunderstorm came through the night and the next day I find that the rear footwell carpets are soaked with water, mainly the driver side. Nothing else in my car seems to have gotten wet. Any ideas on what to do about this and what defect is letting water in? Thanks...

BKH · 23rd June 2007, 05:36

A number of us (myself included) have had that issue. A search will probably turn up some useful info but IIRC there was no definitive answer or fix.

LFC09 · 23rd June 2007, 05:39

Check to see that your door drain holes aren't blocked, then Check the vapour seals (I think that is what they are called), behind the door cards, a liner that helps to run the water down inside the door and out the drain holes.
There is a detailed post on here somewhere (I think by louv) about removing the door cards (caution re airbags is present and active), and repairing the seals.
I had my rear passenger side seal repaired (dealer said there was a small split in it) and problem is gone.

ECB · 23rd June 2007, 05:40

It's probably a leaking vapor barrier in the door. Mine did that also a while back and the dealer fixed it under warranty. If you want a DIY:
http://www.louv.tv/cars/m5/leakydoor/leakydoor.html
Thanks to member Louv for his info.

DouglasABaker · 24th June 2007, 09:27

Any chance you had a window regulator repaired in that door?

As the above posters have indicated, you likely have a bad vapor barrier seal on that door. I just fixed (I hope!) mine yesterday. Really nothing to it - see the link provided previously...

d-

louv · 25th June 2007, 10:06

The seals can fail even if no door repairs have been done. I had both rear door seals fail, and no one had ever taken the rear doors apart. But, as mentioned by Douglas, if anyone has been inside the door (like for window regulator repairs) then the likelihood of failure is very high if they didn't use new sealant when putting it all back together.

Be very careful to carefully clean off all the old sealant, and carefully apply the new to get a good quality seal.

(oh, and don't fire a nailgun through the airbag... but that part's probably obvious)

suprfknman · 26th June 2007, 00:42

The metal trim along where the door meets the window can come loose and water get in there. It is only held on by friction. I took mine off and used a little caulk where it sits to hold it on and have not had a problem since.
Will

alantd · 26th June 2007, 01:50

Common (mine is in next week to try and resolve this).

Most likely candidates are the door seals not allowing proper drainage and sunroof gutters. You should be able to tell which by inspecting as you open the door.

If it is the seals, you'll open the door and a load of water will gush out the bottom of it.

The sunroof gutters connect to pipes, which run across the roof lining and down the rear pillars (I seem to recall). If these get disconnected, the water will find its way down the side of the rear seat, under the rear seat cushion and end up in the footwells. If the vertical carpet panel from the footwell to the rear seat is as wet as the footwell, it'll likely be the gutters.

I recall some people have reproduced the problem when washing the car. Mine's never been quite that bad. A search should turn up some relevant threads.

DanQ · 26th June 2007, 23:16

I've got the same wet rear floor mats after a hard rain too. "To me" the source of the problem is the door holding water until you open it and it drains out. If the door fills up with water until it pours past the vapor barrier, I can't really blame the vapor barrier for being a poor fish tank!

I need to look at what blocks the door drain when the door is closed, because it is obviously clear when the door is open. Water pours out easily, so the drain is NOT plugged inside the door. Does the weather strip (door gasket) block the drain? I'll look more this weekend. I'll reseal the the vapor barrier while I look.

Seems like resealing the vapor barrier is a work around and not the real fix.
Comments?
Thanks
Dan

DouglasABaker · 27th June 2007, 01:02

Actually, if I understand the design intent (which I may not since I'm trying to figure it out after the fact), the "vapor barrier" is actually a waterproof seal that is designed to channel the water to front of the door for drainage.

In fact, if you look closely at the bottom of the door, the holes where the interior trim attaches using the push clips are below the vapor barrier. If the issue were the door filling with water and overflowing, the vapor barrier wouldn't matter.

Based on my investigation this last week, the design is that water runs down the inside of the door (on both the inside of the outer door skin, the outside of the inner door frame and down the vapor barrier), hits the bottom, and channels to the front of the door to drain.

The issue in my car, as backtraced immediately after a light rain that left water in my footwell, is that the vapor barrier was not sealed, and therefore water running down the inside of it was then running down the inside of the inner door frame where is got trapped by the door seals.

So, to answer your question, I believe resealing the vapor barrier completely should resolve the issue since water would then be prevented from running into the interior of the car.

The key observation is that the holes for the plastic trim attachments would leak long before water reached the vapor barrier by filling the door, so I can't see how that is the issue with leakage...

Doug