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Fixed leaking rear door vapor barriers (pics)

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159K views 134 replies 53 participants last post by  John in VA  
T
#1 ·
Thanks to Lunker325 (Brian) for info on how to do this, I fixed my rear doors from the leaking water horror that some M5's suffer from. Very easy DIY. Mx5 is coming over next week to do some work on his car and mentioned he wanted to do this repair so I thought I would go ahead and get my car done so it will be easy to do his. We will be working against the clock on his car, so I wanted to do a trial run.

Remove door panel (One screw on door handle, the rest is just pop locks securing the door. Take out the window switch and the flood light and unplug them.

Clean up area around old seal

Use some silicone to create a new seal (I used 732)

Tape up seal until it cures

Let car air out (I hate the smell of silicone)

Re-install door panel

Pics....

Visible water damage

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Old rubber seal

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I love blue tape

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I know you are digging the power wheels in the background.....

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H
#2 ·
Soon VERY soon.
 
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S
#3 · (Edited)
Not sure what silicone 732 is and why you have all that blue tape holding the barrier on? What you need to do is remove the old barrier and remove all the original black 3M sealer which is extremely tacky and somewhat difficult to remove. However, once you discover how to remove it it gets easier. Once you have like a golf ball sized chunk rolled up you actually use that as a magnet to get the rest of the stuff off by "blotching" the old seal. Again, it's difficult and you need to repeatedly go over and over the old seal until it lifts off. Once you have the old seal off and everything cleaned up just place a new seal along the old path, on the door, not the barrier, as you will see where the old seal was as it contours along the door. You don't need a new barrier unless it has a tear or hole in it. Press every square inch of the barrier back on the new sealent and you don't need tape to hold it and it doesn't need to cure. This "732" stuff that needs to be cured, not sure you should use that. This 3M stuff, I forget the product # can be had at the dealer, or, I did see the EXACT same stuff at Advance Auto type auto parts stores. If anyone wants the product # I can look in the garage.
 
H
#4 ·
sidneyj said:
Not sure what silicone 732 is and why you have all that blue tape holding the barrier on? What you need to do is remove the old barrier and remove all the original black 3M sealer which is extremely tacky and somewhat difficult to remove. However, once you discover how to remove it it gets easier. Once you have like a golf ball sized chunk rolled up you actually use that as a magnet to get the rest of the stuff off by "blotching" the old seal. Again, it's difficult and you need to repeatedly go over and over the old seal until it lifts off. Once you have the old seal off and everything cleaned up just pace a new seal along the old path, on the door, not the barrier, as you will see where the old seal was as it contours along the door. You don't need a new barrier unless it has a tear or hole in it. Press every square inch of the barrier back on the new sealent and you don't need tape to hold it and it doesn't need to cure. This "732" stuff that needs to be cured, not sure you should use that. This 3M stuff, I forget the product # can be had at the dealer, or, I did see the EXACT same stuff at Advance Auto type auto parts stores. If anyone wants the product # I can look in the garage.
Click to expand...

2 things, first if Im reading your post correctly youre saying that you should use the 3M stuff instead of the silicon and its the same exact stuff they used to build the car. If thats correct, then isnt the same thing going to happen again?

Second, silicon is waterproof and Im pretty sure itll last ages longer than the double sided tape that youre referring to.

To each his own but when I do this and its going to be soon because I just found my back foot wells sopping wet, I want a permanent fix so I dont mind having to let it cure nor do I mind using the painters tape to hold it in place until its done so.

I may have read your post wrong. I appreciate you posting an alternative approach but to me I want something thats gonna last longer than it did from the factory. Silicon I know for sure will do that.
 
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#8 · (Edited)
BMW has their own Buytl tape which is the correct way to repair this. Remove the door panel, remove the vapor barrier (do not tear/rip it). It's important to remove all the old butyltape next. Then lay a frash bead of ribbon sealer/tape around the area. You can use a heat gun over vapor barrier quickly, to get the tape nice and sticky. Re-install the door panel and you're done.

Silicone is going to be a major PITA to clean up next go around. Definately would not use this method.

Normally the factory tape fails, because whoever was last in there replacing a window regulator, etc. Didn't take the time to replace the tape. They just tried to reuse it, and as you can see, it never works that way. Not unless you heat it with a heat gun, and try and get it tacky to re-use it.
 
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#21 · (Edited)
BAD TA WS6 said:
BMW has their own Buytl tape which is the correct way to repair this. Remove the door panel, remove the vapor barrier (do not tear/rip it). It's important to remove all the old butyltape next. Then lay a frash bead of ribbon sealer/tape around the area. You can use a heat gun over vapor barrier quickly, to get the tape nice and sticky. Re-install the door panel and you're done.

Silicone is going to be a major PITA to clean up next go around. Definately would not use this method.

Normally the factory tape fails, because whoever was last in there replacing a window regulator, etc. Didn't take the time to replace the tape. They just tried to reuse it, and as you can see, it never works that way. Not unless you heat it with a heat gun, and try and get it tacky to re-use it.
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As Tyrone D mentions above this is what BMW uses. I'm not 100% this is what is used from the factory but this is what's used at the dealership when they repair the barriers or when other repairs are needed behind the barrier. You don't need to use any heat gun on this stuff unless I suppose your installing this in cold temps. This stuff is as tacky as it gets.
 
L
#9 ·
There are several ways to fix this. On my old 540 I used just silcone sealant, plenty of it, and it held up for years until I sold the car. On this car, I used the window weld stuff, AND silcone sealant around the outside edges just to make sure no water would get onto my illuminated door sills, or into the car.
 
T
#10 ·
I personally did not reuse the original stuff because in my eyes it will just fail again. I have every record from my car since it's in-service date, and no one has ever had that door apart. The previous owner was not a DIY guy, EVERYTHING was done att the dealership. 732 is just Industrial Loc Tite silicone that we use at work to fix just about anything that needs to be repaired in a water tight situation. IF I do ever need to get inside that door panel I will cross that bridge when I come to it. I would much rather have to deal with a PIA door repair if a regulator fails than have to worry about the original sealer failing again causing my door to leak again. I can pretty much garuantee this stuff will not leak.

Sometimes OEM isn't the best route to go.

But again, to each his own.....
 
M
#11 ·
Can we come up with a better waterproofing solution than the vapor barrier on the inside of the door skin? Is there something we can drape on the interior of the door metal that might channel water a little better? I'm willing to put in the work here to make sure this doesn't happen.

My initial repair didn't take because I think I didn't do a complete job removing the sealant from the vapor barrier itself. With the hurricane rains yesterday, my car was a boat inside :(. Sucked out the water today, going to go at it again tomorrow, and will look to see if there is a better way to make the seal.

BTW, I got new vapor barriers simply to save myself the time and energy of removing the window weld from the old barriers. It took me 3x as long to clean them than the door metal, and I clearly didn't do a good job. Interestingly enough, the new barriers are a much lighter grey color than the nearly-black/charcoal of the originals.

So, any thoughts on making this thing more water-tight?
 
M
#13 ·
I'm sure half the problem was me. I was rushing it, and probably didn't put enough care into the fix. New vapor seals will help me in the effort area, but if someone wants to come up with something to add to the fix, I'm all ears.
 
T
#14 ·
Huh, maybe my silicone fix is the right way to go? THE MAIN REASON I used 732 silicone is because this stuff will stick to ANYTHING, FOREVER. We use it for just about anything at work (dog food factory) and it seems to hold in any situation. I am confident my doors will not leak again. If I do have to get inside the door for any kind of repair, I know I can just buy a new vapor barrier, if needed, and silicone it again after scraping off the old stuff. But at least I know my door won't leak. Besides, how often do you see someone's rear window regulator failing?
 
K
#15 ·
i used new vapor barriers for the repair the first time.... i even used a heat gun to heat up the 3M window weld to soften it up and create a better seal... it worked great for awhile but then after the huricanne or tropical storm came to the east coast this weekend i noticed my carpet was wet again yesterday... i used to use 732 and a crap lot of other silicones and RTVs overhauling, repairing, and maintaining military and commercial hydraulic and fuel related systems... the stuff works great on skydrol and jet fuel (which are both extremely corrosive)... it's kinda funny i found this thread today as i was telling my girlfriend that i had to find a better solution for sealing up the rear doors last night...
 
B
#18 ·
BMW sells their own, and it's much better than the 3M I've used previously. I've got hundreds of these repairs under my belt, and not a one has ever leaked. As I said, the key is using a heat gun to activate the butyltape. Just applying the tape and setting the vapor barrier in place won't necessarilly fix the issue every time.

You're going to be hacking away at that silicone w/ a razorblade for some time when you go to cross that bridge.
 
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M
#19 ·
Do you have a BMW part number for the sticky stuff? If you are in NH, wanna come down and help me with my door? I could use your expertise and experience with this repair. Dinner/libations/more on me :).
 
D
#22 ·
One more 2003 with leaky rear doors

Hard to believe a $75K car when new has this crappy design. Both rear doors leaking and no information that either rear door ever had any work done on them. And, EASY CARE extended warranty will not cover the costs. $400 for the dealership to repair with new vapor barriers.

What a crock!!
 
S
#28 · (Edited)
DAWGFANM5 said:
Hard to believe a $75K car when new has this crappy design. Both rear doors leaking and no information that either rear door ever had any work done on them. And, EASY CARE extended warranty will not cover the costs. $400 for the dealership to repair with new vapor barriers.

What a crock!!
Click to expand...
I'll do it for $100 :2: $400 sounds about $250 to high! What dealer? Are you 100% sure it's the barrier? When I had mine replaced it was covered under warranty but awhile later I had the door panel off and saw the shoddy job they did. It didn't leak anymore but you could tell they left lots of the 3M bondo stuff and it was put on crooked. If you get the part I could probably help you put it on if you come over to Woodstock.......no charge.
 
M
#23 ·
PSA:

Just redid one rear door seal this weekend after it failed a month or two after the first repair (done by me). Some things learned:

1) when it comes to 3M window weld or other stick stuff, more is not better. I lathered it on, naively, and it probably made things worse and contributed to the failure.
2) use the 3M window weld that comes in tape form. I originally used the caulk gun one, and just didn't have enough experience to know how big a bead to put down (read #1).
3) use new vapor barriers. I know that many of you have reused the old vapor barriers, but given what I saw, new ones should be part and parcel of the repair. My old vapor barrier, which I cleaned very well last time, separated at the adhesive junction. The actual material of the barrier separated from itself, meaning that it was still stick (firmly) to the adhesive, but was still torn open and allowed water to leak through.

#3 caused major leakage again, and on top of that, made it 5x harder to repair. With a layer of this foam stuck to the adhesive stuck to the door, it was near impossible to remove. 50F weather in Boston did not help. I tried using the "ball it up, stick to itself" method to no avail. In the end, it was just elbow grease, and lots of it, that got me a clean strip of metal all the way around to lay a new bead down.

Hopefully, this helps someone down the line. I don't think it contradicts what others have suggested in terms of repair procedures. The old vapor barrier material separating was a huge pain in the rear. For <$40 a barrier, I'd just get new ones. God knows there are more expensive parts on this car.

FWIW, the new barrier is light grey in color, and fits pretty well, except on the trailing edge of the door, at the top, there is an indentation that is just in the wrong place. I inverted it and everything went fine.

Mark
 
T
#24 ·
mchang said:
PSA:

Just redid one rear door seal this weekend after it failed a month or two after the first repair (done by me). Some things learned:

1) when it comes to 3M window weld or other stick stuff, more is not better. I lathered it on, naively, and it probably made things worse and contributed to the failure.
2) use the 3M window weld that comes in tape form. I originally used the caulk gun one, and just didn't have enough experience to know how big a bead to put down (read #1).
3) use new vapor barriers. I know that many of you have reused the old vapor barriers, but given what I saw, new ones should be part and parcel of the repair. My old vapor barrier, which I cleaned very well last time, separated at the adhesive junction. The actual material of the barrier separated from itself, meaning that it was still stick (firmly) to the adhesive, but was still torn open and allowed water to leak through.

#3 caused major leakage again, and on top of that, made it 5x harder to repair. With a layer of this foam stuck to the adhesive stuck to the door, it was near impossible to remove. 50F weather in Boston did not help. I tried using the "ball it up, stick to itself" method to no avail. In the end, it was just elbow grease, and lots of it, that got me a clean strip of metal all the way around to lay a new bead down.

Hopefully, this helps someone down the line. I don't think it contradicts what others have suggested in terms of repair procedures. The old vapor barrier material separating was a huge pain in the rear. For <$40 a barrier, I'd just get new ones. God knows there are more expensive parts on this car.

FWIW, the new barrier is light grey in color, and fits pretty well, except on the trailing edge of the door, at the top, there is an indentation that is just in the wrong place. I inverted it and everything went fine.

Mark
Click to expand...
I rest my case...... my silicone repair > new vapor barriers....... I still have no leaks.......
 
M
#26 ·
timmay: i don't know if the silicone would have prevented the tearing/separating of the material from itself. however, I will acknowledge that the silicone would make a much better adhesive overall. i had already purchased everything, so I did it this way instead of with silicone. I'm sure I'll have to tear into another door eventually. That one will get a new barrier and the living daylights siliconed out of it.
 
M
#27 ·
I also envisioned thermal forming some plastic inserts that go into the two holes, one with a gasketed hole for the door pull cable. I might still do this when I pull the other door apart. Heh.
 
D
#29 ·
Thanks...just had it done! Roughly $350 in labor and $50 in parts at Global Imports...(Definitely NOT HAPPY with them)We'll see if it holds up. EASY CARE extended warranty would not cover it. Spoke to the Service Manager and he says he's seen alot of this problem lately with all the rain we have had. Appreciate your offer to help! All the best, Greg
 
S
#39 ·
That sticky stuff ( it's actually called window weld by 3M) acts like a magnet. You take off a chunck and then blotch against the old sticky stuff. Takes time but $350 I don't think so. I can assure you the dealers are not cleaning it.

DAWGFANM5 said:
That's what I figured...$350 was not that bad....I was more pi$$ed that Easy Care would not cover it.....pulling both door panels,all that cleaning of the old stuff, replacing the vapor barriers, replacing the door panels....I can live with the $350 in labor.
Click to expand...
So you have 2 leaks? Makes more sense on $350 but still do it yourself. The door panels come off in literaly 5 minutes. Plus you do it yourself you can get it real good and clean because the dealer will not spend that long in cleaning off the old window weld......I mean sticky stuff.
 
M
#38 ·
The design of the door has two big holes in it. The water comes into the door and is supposed to run down the vapor barrier and get directed into the bottom of the door where it drains out. The vapor seal often comes unstuck, and therefore does not seal, along the bottom and trailing edge. Great picture here:

Vapor barrier removed
 
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