Door Membrane leak or I thought it was!

The Moo

Senior member
 Warwickshire
Car is at dealers at present having oil service and a few other issues sorted. (Keeping it overnight)

I have a leak. Water appears to be running over the plastic kick plate into cockpit. I suggested that they look at the membrane in the driver's door. They assure me that they have and that it is not damaged and they have performed a leak test and cannot get the car to leak! It generally leaks when the rain is heavy. I can only presume they have checked the other obvious things such as door seals etc.

Any alternative suggestions as too where water might be coming in?
 
In my other BMW convertibles I had leaks at the corner joint of the roof to windscreen pillar. It only happened in HEAVY rain or a carwash and it may be dribbling down the rubber down the side of the window then past the door onto the bottom plate. Mine just dripped onto my leg and P'd me off.
 
I've never had a problem with mine, but if I did then I'd suspect the junction where the "B-pillar" of the roof curves around the top of the door glass. There doesn't seem to be as much overlap of the glass/seal there compared to other areas of the door seal/glass join.
 
It's certainly a common spot and fixing the membrane stopped mine leaking. I also added an extra hole in the rubber seal at the lowest point (where it happens to drip over and into the footwell) in case any got by.

I'd suggest put a light dust of talc on the seal in a couple of places and see if water runs over it. You can track back to source this way.
 
Trouble is at the moment they can't replicate the leak and they are adamant that the membrane is OK. I wonder if the dramatic fall in tempearture is having an effect on the rubber seals?
 
The Moo said:
Trouble is at the moment they can't replicate the leak and they are adamant that the membrane is OK. I wonder if the dramatic fall in tempearture is having an effect on the rubber seals?


If you can't replicate it for long enough then at some point that will constitute a 'fix', or if it is so rare then I wouldn't worry about it.
 
test it yourself, the stealers normally says they can't find the leak no matter what test they do, yet when i did mine myself, i could easily reproduce it.

there is a thread here somewhere about it

anyway to check if its the door membrane, open the doors (windows up) and put a running hose at the window channel left to right repeatedly. in less than 30 seconds look at the bottom of the inner door, if there is water then its your inner door membrane. repeat this procedure at the stealers to show it does leak.

if it does not, its probably from the A-pillars. to check, run a hose thru the A-pillar base (just near the side mirror, door and quarter panel while door is closed. normally water runs thru the A-pillar base and then runs down to the lowest point of the weather strip.

both happened on my z4, so check carefully
 
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