Tales from the Vapor Barrier ... Part II

[paul p]

Considered updating Part I, but wanted the useful info at the top.

Bentleys not needed. For something like this, between Pelican Parts how-to articles, and obviously here, what's the point.
https://www.pelicanparts.com/BMW/techarticles/BMW-5-Series-E39/35-BODY-Rear_Door_Panel_Removal/35-BODY-Rear_Door_Panel_Removal.htm
Torque specs not critical

First thing, removing the door card is a little tricky if you have the window shades. It worked better for me to undo it from the door so it comes off with the panel. That way you don't have to deal with the fiddly small screw at the front where it attaches to the panel. The top of the shade needs to be secured outside the trim line when you reinstall, but a piece of painters tape makes that pretty easy.

A lot of the tutorials mention heating up the old gasket material to make it easier to get off, but I found the opposite to be true. Maybe if you're using a scraper, but most of it came off in big strips pulling at it by hand. After heating with a blow dryer it got mushy and messy. A smear always stayed stuck to everything then.

Didn't clean all of it, kept the residue at the outside edge as a guide. No multi solvent clean up, just some drug store isopropyl alcohol on both metal and barrier.

Been using 3M Window-Weld in a caulk tube, which may be overkill. Certainly one of the more expensive options, almost $30 OTC in the city. And u only can do one door per tube..
Also, whatever u do, wear gloves. Uncured, this stuff sticks to everything, including your hands.
Even going at them with a brush and pumice GoJo after, had stains on my fingers for a week.

*EDIT*
I also noticed at the top of the door card the inner panel was separating from the fiberboard support so I put a few dabs of hot glue to make it a little more solid. Ideally marine epoxy would have been a better choice IMO, but none available. My wife's glue gun was just sitting there in the craft area that evening.

But yeah ... dry footwells. Priceless

[StephenVA]

3M Adhesive remover will clean your hands nicely. Leave it on too long and it will remove the skin too!
Thanks for posting as dry footwells are a nice thing to have as Winter is coming....

[paul p]

OK, really questioning the choice of the caulk gun method with the sealant.

Who's had luck with the OEM equivalent rope?

[StephenVA]

Me Easy job. Used the 3M rope stuff made the job easy. If you have tried to get the old sealant to stick to your vapor barriers without success order in the 3M sealer and a vapor barrier. DO NOT use RTV, as when your window regulator fails (this part failure is a when not if) you will have to get order a new one as it will tear. There is enough to do two doors on one roll.

Tip: REMOVE ALL THE OLD SEALANT and clean the door frame. Some even use the 3M primer as a prep to ensure it sticks. Take your time and do it right once. Your dry carpet will tank you when winter sets in. I used 3M adhesive remover as it is my go to stuff to clean anything tar/petroleum based.

3M 08621 Window-Weld 5/16" x 15' Round Ribbon Sealer Roll
https://www.amazon.com/3M-08621-Window-Weld-Ribbon-Sealer/dp/B00063Z4FM/ref=sr_1_fkmr3_1?ie=UTF8&qid=1538182591&sr=8-1-fkmr3&keywords=3M%E2%84%A2+Windo-Weld%E2%84%A2+Round+Ribbon+Sealer%2C+08621%2C+5%2F 16+in+x+15+ft+Roll

https://multimedia.3m.com/mws/media/366728P/3mtm-windo-weldtm-ribbon-sealer-black-08621.jpg










08621 Window-Weld 5/16" x 15' Round Ribbon Sealer Roll

[paul p]

Me, Used the 3M rope stuff. There is enough to do two doors on one roll.

3M 08621 Window-Weld 5/16" x 15' Round Ribbon Sealer Roll
https://www.amazon.com/3M-08621-Window-Weld-Ribbon-Sealer/dp/B00063Z4FM/


Wow. At <$10 per door, we're talking a significant savings.



you will have to get order a new one as it will tear.
Tip: REMOVE ALL THE OLD SEALANT and clean the door frame. Some even use the 3M primer as a prep to ensure it sticks. Take your time and do it right once.

I wonder how many leaky doors are not just age but a previous quick and dirty window fix. They didn't bother resealing the barrier short of heating the old goop up and expecting just the pressure from the panel to seal it.
Getting the door metal clean should be a no brainer. But if you're in a hurry, or a $tealer monkey doing a book time job. *shrugs*

Does the 3M Adhesive remover do a good job of cleaning up the barrier foam w/o dissolving it? That's kind of why I went with the tube. It's totally uncured and stuck to the barrier (and anything else) really well.

[StephenVA]

The barrier is really a 1.5 use product. I have had a few chances of luck getting goo off without too much challenges and getting new sealant to stick. Once the barrier shows a grease mark the sealant never sticks again.

[paul p]

The barrier is really a 1.5 use product.
And of course they're $50ish. Typical ... B(reak)M(y)W(allet).


I have had a few chances of luck getting goo off without too much challenges and getting new sealant to stick. Once the barrier shows a grease mark the sealant never sticks again.
Hence maybe the caulk tube WWeld may be cheaper in the end if it still bonds to a minimally prepped barrier.
Makes me want to pull one of the finished door cards to see how well it's actually sticking after curing.

Also updated original post since I forgot to mention something.

[geargrinder]

Great notes above, agree w/ all been said re: options & overkill & importance of cleanliness etc.

Despite being called the same thing, the tube Window Weld and the roll Window Weld are 2 radically different things. 3M's "Window Weld" is really a 'broad product line' brand meaning the individual products can be pretty different technology.

The roll stuff above is still Butyl rubber - same as factory stuff.

The caulk tube WW is a mega-bonding urethane, that stuff is basically more of a process of casting a hard synthetic rubber than it is an RTV-type adhesive. The downside of it is it is SO strong and sticks REALLY well - like maybe TOO well. Like next time you might want to get into the door to fix something if you have to cut that stuff off again you almost certainly will have to toss the membrane, and even after that might struggle to get it cut off the door without scraping up the paint. That is addition to the mentioned problems of it gooping on something else during the job and leaving a permanent glob of hard rubber. It is the 'nuclear option'. If you really feel you need that then well... go for it, the stuff is mad strong. But I'd try to avoid it.

Mostly I'd always try to get a factory-style seal to work. The factory seal tends to work totally fine until gorilla mechanics or clown owners get in the door to fix a regulator and then don't take it seriously, so there's no reason you shouldn't be able to replicate that.

The 3M stuff is a very high quality version of the standard auto parts Butyl rope caulk so I'm sure its an excellent choice. The auto-part store versions (which I've used a number of times on other cars/places) is indeed often crappy - not enough surface tack and often kind of dried out (probably has a shelf-life spec that is completely ignored at the FLAPS). That 3M with the protective film on it is probably much better, plus ordering it only and getting fresh stuff is prob good idea.

As mentioned here the key is always to clean and dry the surfaces and make sure the surface of the butyl stays 'virgin' i.e. don't get it all handled up w/ your fingers as you're applying it. My blind guess is a lotta guys who fail with the caulk rope are not only using crappy butyl, and not cleaning surfaces well enough, but and/or they handle it up without paying attention and lose the virgin surface tack as they are doing the install.

[Mike WW]

I've usually been able to just reuse the original sealant, but occasionally have had to add to it. I just use cheap black butyl tape. Same thing the factory uses and seems to stay soft forever. Reusing the old does require reshaping it so it's not already compressed, but it seems to stick again without any problems. You can feel it too, as you stick it on push on it a bit to compress it and seal it. I've had lots of door panels off, transfered window blinds between a pair of tourings for one thing and only had one leaky door. Nothing dramatic about it, I just wasn't as careful as I should have been.

RV supply places carry butyl tape if you don't feel like waiting for Amazon.

[BimmrMeUpSnotty]

When I do my doors, cleaning all the old butyl, or we’ve always called it DumDum in the body business, the dumdum should be soft at room temperature. If what you have is hard, either it can be revived by warming it up, but it can get real guey if heated up too much, I’d toss it, a new roll is only about $15. If you have the hardened stuff, apply it, hit it with a heat gun, it softens it up. But before I apply the dumdum, I use 3M adhesive primer #94, it is an adhesive promoter, comes in a 4oz can that I get, I use epoxy brushes to apply it to the door shells mating surface, give it a few mins to set up, then apply the dumdum. I then apply the primer to the vapor barrier, of course cleaned up and free of debris, once it has set up, I do heat up the dumdum, apply the barrier to the door, I then use a 1” paint roller to mash down the barrier to the door shell. It is the same way I do it on the newer customer BMW doors at work, just as I do on my own.
3M also sells the adhesive promoter primer in swabs, wear gloves, you get this stuff on you, your fingers will pick up all kinds of stuff and it becomes a part of you, lots of scrubbing is involved in removing it. 3M also sells it in a pen, never used that yet.

[StephenVA]

I could find a picture of Butyl tape that i purchased off amazon so sorry for the wrong image. Use the BUTYL stuff that 3 m makes. need to find that box now....

[geargrinder]

I could find a picture of Butyl tape that i purchased off amazon so sorry for the wrong image. Use the BUTYL stuff that 3 m makes. need to find that box now....

That other WW pic IS a 3M butyl tape product... that's what I was sayin'.

[philly98540]

My 2 cents

I've previously used new 3m butly rope applied after impeccibly cleaning everything and using a heat gun preheat prior to applying the vapor barrier. Did not use the primer though... Seemed to work and hold great for about 5 or so years, then I noticed a wet door sill after a wash, so it needed to be re-done. Maybe the primer is the missing link, as that is awesome bonding stuff. Snotty's method seems bullitproof with the primer.

My thinking is the butyl gets a bit hard and more brittle in the cold winter and can loose bond with door slams and such, but I'm speculating on that. The factory butly method almost always eventually leaks as that is why we talk about it LOL.

I now go a slightly lazyier route that seems to work surprisingly well for me. I have been using 100% black silicone caulk from the home center. After a good cleaning of both surfaces, I apply a generous bead to the door and then install the vapor barrier. No leaks after many years 5+ (total guess...) I just had to fix a rear reg the other month, so had to remove one of the barriers I siliconed many years back. I could pull off the barrier without too much effort, then peel and scrape off the old silicone with less work than the butyl removal. I re-did the same caulk seal and all seems good. Still on original 1998 vapor barriers. The silicone stays rubbery when cold and seems to bond well enough to keep the seal over time. It definalty does not bond as stong as the buty when its room temp though, but it seems to seal quite well enough and stay sealed over the seasons. /nonbmwhack

[geargrinder]

Yep, I also noticed Snotty's pro-method is pretty much exactly what Stephen says is his proven technique. Interesting that the RTV-type method worked for you, because you hear a lot that that's a NON successful route for people... maybe again its the surface cleaning that's key... I'll prob stick w/ dumdum myself if & when but honestly I've had zero problems. Meaning of course having said that - when it rains this afternoon I'll find a giant puddle in the backseat I'm sure.