water in rear floor area

[300kplus]

98 e39 M62
I have my sunroof drains cleaned enough to know they are not clogged. What are the most common causes of this? TIA!

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[Yonkers320is]

Vapor barrier on the doors
Remove door panels and check the barrier and the butyl adhesive

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[jclausen]

Door vapor barriers yup

[MotorMouth93]

Unless you want it to stay wet for weeks you need to pull up the rear carpet and dry it out.

[BimmrMeUpSnotty]

A BILLION vapor barriers and counting.....

[crazy4trains]

Pull the rear seat, pull up the carpet and rent a dehumidifier. That foam holds water for an eternity.

[300kplus]

one BILLION...ONE!

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[Frankie]

"Door vapor barriers": I doubt it.

Water would have to travel up and over the rubber seal around the door opening. Go look at your door cards with door closed. Leaking vapor barriers would result in water draining harmlessly onto the door sills.

I suspect your roof antenna seal.

[BimmrMeUpSnotty]

"Door vapor barriers": I doubt it.

Water would have to travel up and over the rubber seal around the door opening. Go look at your door cards with door closed. Leaking vapor barriers would result in water draining harmlessly onto the door sills.

I suspect your roof antenna seal.

Man, what E39 reality have you been living in??? Not saying that it couldn’t be leaking from the antennae seal, if op had a wagon. He has a sedan, so it is not the cell phone antennae like on our wagons. And water in the rear floor area is either the sunroof drains, which usually pop free or go up front, so it boils down to the usual culprit, the vapor barriers, a result of bad re-installation after replacement of these infamously horrible window regulators that we have.

[StephenVA]

#1 is rear door seal toward the back bottom of the door frame. Every E39 especially the early ones have this issue. Lots of posting on repair approaches. Personally I would pull off the panel, inspect and would replace the seal and use the 3M buntal seal tape

The coffee holder idea is free

[BimmrMeUpSnotty]

That the new Uro cupholder?

[ross1]

Uro premium

[Sleepyhead97]

Uro premium

[StephenVA]

ha ha ha "Premium" loved that one.

[E39 Newbie]

+1 on the rear door vapor barrier. We had some really strong winds and heavy rain a couple months back. A couple days later I went out to find the front carpet wet. I then looked in the back and found Lake BMW. The water had leached up to the front via all the foam padding. Long story short, I pulled up the carpeting as best as I could, without removing the seat, and let it sit for a week. Still wet. I then squeezed as much water out as I could and put one of those "floor drying" fans in the car and let it sit for several days. A few more squeezes and several days and the foam was dry. I had no idea the foam could hold that much water.

I then took off the door panel and the vapor barrier was just hanging by a few spots. PO had some clown fix the regulator but didn't redo the butyl.

[Frankie]

So if the vapor barrier is indeed the culprit, how does water travel up and over the door opening rubber seal?

[BimmrMeUpSnotty]

How does it hop over.....

Well, all car doors take a ton of water in through all the gaskets. All cars do this, there are no cars that are all completely sealed., if they were, you would have blown out eardrums every time you hopped in and slammed the doors. The bottom of the doors have drain holes, usually at the bottom corners. If they get dirty and clogged up, for instance, people who usually park the car under trees, trees crap out a ton of tree debris. So, perfect example, when those car owners that never clean the cars, cars parked under trees always end up with a ton of tree crap, and leaves that pile up in the creases between the hood and cowlings, in our BMW’s, debris collects in the well underneath the drivers side cabin filter, if you neglect that, debris clogs up that half inch drain hole, water pools up in there, brake booster can end up sucking in water, because the same fool neglected to clean out the debris in the side drain ports that drain out behind the front fenders, always clear those out! I do it every time I have the hood open, checking fluids, oil, the drain in underneath the cabin filter, I check and clean out once every couple months. I don’t ever park under trees, yet I am still cleaning out tree crap.

Well, the same thing happens in the doors, every time it rains, debris is getting in there. You will be amazed at the amount of water that flows through the doors. So the vapor barriers if contained properly, will keep water from coming in, but....
Say you replaced a bad window regulator, and failed to properly seal the vapor barrier with fresh new butyl rubber, clean out the old crap, eventually, the.vapor barrier will pop free from the door shell, usually at the bottom, right around the light fixture on the inner door panel that illuminates the ground . Water does not have to necessarily pool up, but if you fail to clean out the door she’ll when you have it opened up, I have seen this in many cars, usually cars that are constantly parked under trees. Water will over flow into the failed vapor barrier.

The other way water flows in..... aside from the sunroof drains being compromised by tree debris, or the hose tearing open, or plucked off the sunroof cassette, is again, through the vapor barrier which was still properly fixed to the door, water drips down the quarter window bar, onto the bowden cable to the door handle, from the latch, happened to my older green wagon, water then runs down the cable, through the vapor barrier, into the car.
so I had to pull the vapor barrier free up top, used new butyl rubber and sealed the back side of the vapor barrier to the cable sheathing, and did the same thing and sealed the vapor barrier to the cable sheathing on the front side, have never had water in my rear floor ever since. The other way water over flows is in a ridiculous torrent of rain and the drain holes just cannot drain out the water fast enough.

[Yonkers320is]

So if the vapor barrier is indeed the culprit, how does water travel up and over the door opening rubber seal?

Because the door rain drain gets blocked by the door seal and the water seeps in. My car has no sunroof, and the carpet on the passenger rear got so wet that it rusted the floor. Previous owner never noticed and ended in the floorpan getting a hole.

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[Yonkers320is]

How does it hop over.....

Well, all car doors take a ton of water in through all the gaskets. All cars do this, there are no cars that are all completely sealed., if they were, you would have blown out eardrums every time you hopped in and slammed the doors. The bottom of the doors have drain holes, usually at the bottom corners. If they get dirty and clogged up, for instance, people who usually park the car under trees, trees crap out a ton of tree debris. So, perfect example, when those car owners that never clean the cars, cars parked under trees always end up with a ton of tree crap, and leaves that pile up in the creases between the hood and cowlings, in our BMW’s, debris collects in the well underneath the drivers side cabin filter, if you neglect that, debris clogs up that half inch drain hole, water pools up in there, brake booster can end up sucking in water, because the same fool neglected to clean out the debris in the side drain ports that drain out behind the front fenders, always clear those out! I do it every time I have the hood open, checking fluids, oil, the drain in underneath the cabin filter, I check and clean out once every couple months. I don’t ever park under trees, yet I am still cleaning out tree crap.

Well, the same thing happens in the doors, every time it rains, debris is getting in there. You will be amazed at the amount of water that flows through the doors. So the vapor barriers if contained properly, will keep water from coming in, but....
Say you replaced a bad window regulator, and failed to properly seal the vapor barrier with fresh new butyl rubber, clean out the old crap, eventually, the.vapor barrier will pop free from the door shell, usually at the bottom, right around the light fixture on the inner door panel that illuminates the ground . Water does not have to necessarily pool up, but if you fail to clean out the door she’ll when you have it opened up, I have seen this in many cars, usually cars that are constantly parked under trees. Water will over flow into the failed vapor barrier.

The other way water flows in..... aside from the sunroof drains being compromised by tree debris, or the hose tearing open, or plucked off the sunroof cassette, is again, through the vapor barrier which was still properly fixed to the door, water drips down the quarter window bar, onto the bowden cable to the door handle, from the latch, happened to my older green wagon, water then runs down the cable, through the vapor barrier, into the car.
so I had to pull the vapor barrier free up top, used new butyl rubber and sealed the back side of the vapor barrier to the cable sheathing, and did the same thing and sealed the vapor barrier to the cable sheathing on the front side, have never had water in my rear floor ever since. The other way water over flows is in a ridiculous torrent of rain and the drain holes just cannot drain out the water fast enough.

I am replacing the windshield gasket and the plastic cowl and the pieces on the bottom corner of the windshield, look like triangles, the amount of dirt and tree crap that gets trapped in there, collecting moisture. And clogging drains.

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[StephenVA]

If you type in the search feature, you will see hundreds of posts where the skeptics to vapor barrier leaks, post their failures to fix the problem of water coming in through the door panels. My recommendation is to skip the pain and reseal those vapors/ sound deadener panels and resolve the problem.

are the vapor barriers the only point of potential water coming into the interior? No, but they are the number one on the list.

[E39 Newbie]

I, too, was a skeptic. I didn't see how water could fill the door, and then get up over the door seal. Well, as I stated above, after a very windy and hard rain I became a believer. I had the entire sunroof cassette out when I redid the sunroof a couple years ago, so I was pretty sure it wasn't a sunroof drain. I had checked them all thoroughly before reassembly. The car was parked under a carport but the rear was sticking out from underneath. The RR corner was exposed to the elements and that's where the intrusion happened.

[Frankie]

I will concede - for the moment - that a defective vapor barrier is the problem. Still, the explanations offered are weak.

Even if the vapor barrier were missing entirely, how could water penetrate the vinyl trim layer of the door card and travel around the rubber door seal? In this case, water would soak the fiber board of the door card and exit the seam at bottom, below the door seal. This would create a mildew, soggy mess of the door card. But still no water on the floor.

Water has to enter the car from ABOVE the door seal. The only way I can see that happening is thru the courtesy light (which sits above the rubber seal). Water has to drip directly from the light onto the carpet.

I suppose water could run off the window glass and drip onto the bulb/lens due to the curvature of glass and door frame. But only if the bottom section of the vapor barrier is missing.

Perhaps that's exactly the issue here.

The proof would be rusty door light contacts, with water stains on the surrounding fiber board. How devious. How resourceful. Foiled again! Of course, this presents us with a possible solution: caulk the door light.

[crazy4trains]

Somewhere, somebody (don't you love it when a post starts this way) somebody drew a cross section through the door and body showing the locations of all the relevant bits and pieces. When you see that cross section it is obvious how water can get past the vapor barrier and into the car to soak the carpet and padding. Now if I could only find that section.

[BimmrMeUpSnotty]

It comes through the light fixture. This subject has been wrung out and stepped on a couple thousand times over, most on here have had the issue, I have gone through the cycle at least 12 to 15 times over. And not because of shoddy work by myself, well, ok, that is a Snotty lie. It was my fault a couple of times when my window regs finally gave out on my very first E39 for the very first time in their lives, pre internet, nobody to blame but myself, and I corrected it, without Youtube, I’m guilty, man enough to admit it, I did what every PO has done to me every time I get crazy hair up my butt and buy another fine example from the Dingleballfing plant in the Fatherland. Actually, that was another lie, the guy I bought my current green 528 wagon, Jaxplanet, Jack really took care of that car, did a good job of the upkeep on it, and told me about the two problems that he knew about, but was just done with his case of Ethirtynitis. But I have gone through this so many times, I could pretty much do a stupid window regulator and revamp the vapor barrier properly, I bet that I could do it in the dark, with four blindfolds on, maybe even five.

[StephenVA]

I am in 100% with Snotty on this one myself, as I have tried the following on multiple E39 applications (all were leaking when purchased, some more than others)
1. Reheat and mash the existing Butyl sealant against the original vapor/sound deadener - Results lasted less than 4 months in summer heat.
2. Replace sections on the Butyl sealant where it was loose from the door frame - Results lasted one year.
3. Replaced vapor/sound deadener, cleaned all sealant residue from door and reinstall - no leaks no issues going on 2 years.

Read one too many stories of duct taped repairs, bathtub caulking attempts, and band aid repairs all ending in failures or a mess on the next attempt to repair/replace window regs or door/window switch hardware to ever do a band aid approach again. Do it right once for a lifetime of enjoyment...