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Thread: Interior water leak. Yes I know the basics and usual suspects.

  1. #1
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    Post Interior water leak. Yes I know the basics and usual suspects.

    Yes I know all about the vapor barriers and butyl, I already had a roll in the garage.

    We finally got a bit of water here in Calif, ~2 feet in 3 weeks or so. Rear passenger footwell almost had standing water, pulled the mat out, thru some towels in a few days later it seemed dry. But I know about the fuses. So a few days later I pulled the front seat etc. Yep, lots of water, saturated foam and I probably vacuumed out 6 ounces. There's just a hint of that ugly orange stuff, I think I dodged it on this one.
    E39fusebox.jpg

    Questions.
    I recently had the windshield replaced. Silent, no air leaks, likely to have leaked enough to get all the way in back? Usually parked downhill, but not always. Where is it visible while leaking if it is? Run water over it to test or does it have to be sprayed?
    Redid the rear door (all passenger side) vapor barrier. Bottom appeared to be good, but the part that angles up towards the wheel well was not well sealed. Thoughts?
    I doubt it's the sunroof, it does get used, but there's not a lot of tree debris in the area to plug things up.

    Thinking about slathering the fuse box in grease. F that water, if it's full of grease, water isn't going to get in there. Crazy, brilliant or both?

    I do have it pretty dry between vacuuming and a leaf blower running all day, but still apart with rain predicted tomorrow, so it may be a good test.
    98 328is
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  2. #2
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    I'd start with a smoker.. Fill up the interior with smoke and see where it escapes. Works on engines..
    Last edited by SW530; 02-02-2023 at 07:41 AM.
    A great ending is all you'll see..
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  3. #3
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    You've probably thought of this already but check if this area is wet:

    ac water ingress.png

    That's by the carpeted upper left-hand corner.

    It's caused by the ac drain being clogged.

    It stumped me for a while last year. I thought it was was door vaper barriers failing again, so I redid those, and had the interior apart twice to dry everything out, after everything got wet the second time.

    Blowing compressed air into the ac drain fixed this. it took like 30 seconds.

    Mine was just really acting up when it was hot and humid.

  4. #4
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    Quote Originally Posted by SW530 View Post
    I'd start with a smoker.. Fill up the interior with smoke and see where it escapes. Works on engines..
    FUUU know!
    these things use mineral oil and stink
    Last edited by ross1; 02-02-2023 at 10:01 AM.

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  5. #5
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    Not the A/C drain, although it is wet underneath up towards that area, A/C use, even with the goofy defroster setup has been minimal. Windshield concerns me, I don't know how to test or where to look.

    But unless someone screams no, with an explanation, I think I'm going to slather that fuse block with grease. GM did something similar for years, and even being the rabid GM hater I am, I see some logic in them greasing the base of exterior bulbs to prevent corrosion. I know, better to prevent water from getting in, but kind of as an insurance policy in case it does.
    98 328is
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  6. #6
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    Quote Originally Posted by ross1 View Post
    FUUU know!
    these things use mineral oil and stink
    That depends on the mineral oil used. The mineral oil I use has almost no smell. There is an initial smell as you get it going, but you can do that outside your car. I imagine you'd need to clean the insides of the windows though. At the worst I'd run the ozone machine inside the car for a few hours. If you suspected the windshield of leaking you could direct smoke along the perimeter and have someone watch on the outside.
    A great ending is all you'll see..
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  7. #7
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    Quote Originally Posted by Mike WW View Post
    Rear passenger footwell almost had standing water...Redid the rear door (all passenger side) vapor barrier...
    Mike,

    You unwittingly said it yourself: the problem is almost certainly your right rear door.

    Here's how it happens:

    Water sheets from the rear window and streams into the door cavity past the exterior seal. The poorly attached vapor barrier allows water to escape onto the door card, where it leaks from the lower courtesy light and drips onto the carpet. Your door cavity water drains may also be clogged with debris, causing water to overflow past the vapor barrier.

    Solution: you MUST re-seat that vapor barrier, paying special attention to the lower sections. If the barrier is torn, replace with new. Check your door drains too.

    Now, go forth and sin no more.

    Frankie
    Texas, USA
    frankies-bmw.com

  8. #8
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    Quote Originally Posted by Frankie View Post
    Mike,

    You unwittingly said it yourself: the problem is almost certainly your right rear door.

    Here's how it happens:

    Water sheets from the rear window and streams into the door cavity past the exterior seal. The poorly attached vapor barrier allows water to escape onto the door card, where it leaks from the lower courtesy light and drips onto the carpet. Your door cavity water drains may also be clogged with debris, causing water to overflow past the vapor barrier.

    Solution: you MUST re-seat that vapor barrier, paying special attention to the lower sections. If the barrier is torn, replace with new. Check your door drains too.

    Now, go forth and sin no more.
    Actually that was both my first thought and the first thing I did. The angled portion was not sealing but the bottom part was. Still got the leaf blower going trying to dry it out, I thought I was done but discovered more water in back. I did slather the hell out of the fuse area with grease, just in case it is the windshield and going to occur again.
    98 328is
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  9. #9
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    Quote Originally Posted by Mike WW View Post
    Actually that was both my first thought and the first thing I did. The angled portion was not sealing but the bottom part was. Still got the leaf blower going trying to dry it out, I thought I was done but discovered more water in back. I did slather the hell out of the fuse area with grease, just in case it is the windshield and going to occur again.
    I had this happen a couple years ago during a very windy rainstorm. It took days to dry things out. I had to pull the carpet up halfway, use a zillion towels to soak the water out of the foam, and then use one of those largish cylindrical fans for the better part of a week. It's staggering how much water that carpet can hold.
    Current stable:
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