I’ve been plagued with a leaking rear door vapor barrier on the passenger side, and did something about it.
When that seal at the bottom leaks, water comes into the floor pan.
Many thanks to Tyrone D. for his input on the M5 Board and for the part number for the product that I initially used to repair my rear door vapor barrier. I was unable to get adhesion between the vapor barrier and the butyl, and ended up using silicone to seal the vapor barrier to the metal door frame. Here is the article that helped me:
http://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/142940-fixed-leaking-rear-door-vapor-barriers-pics.html
Removing the Door Panel
There is a little plastic screw hole cover in the middle of the door handle recess. I used a plastic pry tool to pop out the cover. Remove the screw. Use the pry tool to wedge between the fiberglass door panel and the steel door frame, and selectively pop out each plastic connector around the sides and the bottom. On the top, press down the door lock, and gently pull the top lip out and over the door lock. Carefully disconnect electrical connections.
Preparing Surfaces
It is necessary to remove old adhesive, and to clean both surfaces prior to sealing the vapor barrier. Removing the old adhesive is non trivial. I was able to slowly separate the closed cell foam vapor barrier from the adhesive, and to start prying a piece of the old adhesive away from the steel by rolling it into a tacky black ball. 20/20 hind sight, I would have used my heat gun to help loosen it up. After removing the adhesive, clean both surfaces well.
Applying New Adhesive
Although I looked for the 1/4″ bead of adhesive previously referenced on the M5 Board, only the 3/8″ bead was in stock at the local auto parts store. I figured more was better since there would be more surface area for adhesive to stick.
Here are the two items I bought for my repair that initially worked well for me, even though I ended up removing the butyl Windo-Weld Ribbon Sealer, and using silicone caulk to make the seal:
3M# 08612 – Windo-Weld Ribbon Sealer, 3/8″ x 15′ round bead
3M# 03618 – Adhesive Remover – 12 oz aerosol – helps remove tar, attachment tape, and bumper sticker adhesive
The adhesive comes in a roll with a wax paper barrier between coils:
Attach the roll of adhesive to a spot on the steel frame nearest the top outermost point, and work the roll around the steel frame:
Remove the wax paper backing from the roll of adhesive. Firmly press the closed cell foam vapor barrier into place. If I had to do it over again, I would probably hit the new adhesive with a little heat from my heat gun to make it as tacky as possible, and then press barrier into place.
Put the door panel back on the door. I had my son take the garden hose, spray around door, and allow me to test my seal from the inside of the car by pressing my hand onto the rear floor panel to check for water. Repair was successful for a while. However, the bottom lip of the vapor barrier pealed away from the metal door frame, and another repair was necessary.
Here’s another YouTube video that helped me:
The subsequent repair after the failure of the butyl seal to the closed cell foam vapor barrier required much work mainly to remove the butyl and to prepare both surfaces, the door and the vapor barrier.
Folks, butyl is nasty. Be prepared.
For the butyl, I used a heat gun (fancy hair dryer) to soften the butyl, and then scraped off the bulk of the butyl with a nylon trim tool. I rolled up the bulk of the butyl into a ball, and used the butyl ball to press against the vapor barrier and the door around the perimeter of the seal, and remove more butyl since it adheres better to the ball of butyl than the other surfaces. It adheres well to your hands, tools, and everything else is touches. It just does not adhere well to my 2003 closed cell foam vapor barrier.
To prepare the surfaces, the only cleaner/degreaser that I have in my shed that would dissolve the butyl is mineral spirits. I got out a roll of paper towels, trash can, and mineral spirits, and thoroughly cleaned all surfaces around perimeter, wiped off all excess residue, let it dry, and re-sealed it with good old silicone caulk last night. I checked it this morning, and think it worked.
Happy maintenance!
Best regards,
Jim
