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Old 12-30-2012, 12:21 AM
NZ BMW NZ BMW is offline
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Location: New Zealand
Join Date: Apr 2011
Posts: 274
Mein Auto: 2007 X5
Trying to track water, not sure if vapor barrier

Hi Team,

I've got a couple of questions about the rear door/vapor barrier seals and I'm not sure they've been answered based on a search of this forum and others.

Most people know that the vapor barrier is broken/compromised when they arrive at the car after heavy rain to find that there is a small pond in the back floor. I don't have this symptom.

Knowing there was a thunderstorm approaching and being sure that I had a vapor barrier issue I taped up my rear windows with some electrical insulation tape (it's what I had on hand). See below. I'm pretty sure I sealed the window fairly well and even after the storm the tape is still holding well. I did not tape up the rest of the door.

Anyway when I open the door after the storm I get a small splash of water from off the doorsill - and then some drains out of the door, looks to be from the drain hole. None of this is making its way into the cabin of the car. (Pictures below). It looks to my untrained eye that water may be getting caught between the inner seals (the ones on the door and car body which join) and the weather stripping/seal which is on the outer side of the door.

I thought the vapor barrier issue allows water to enter the car not simply hold it in the doorsill. Any ideas? The front doors have no water on the sills at all and don't drip water after a storm.

Image one: Tape - I thought this is where water enters/breaches the vapor barrier, is my water coming from somewhere else?

Image 2: wet doorsill - both the body of the car and the sill-plate are wet, but not further inside.

Image 3: underside of door - water between the two seals.

Last edited by NZ BMW; 12-30-2012 at 12:24 AM.
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