I thought I had my rear door finally waterproofed, taking special care when replacing the regulator panel (lock mechanism repair). 3 doors finally are opening again, and on the first pull! (thanks Andreas for all the tips!). But, after torrential rain yesterday, I found water all along the edge of the door (below where the latch is located) and car frame (at/below the strike plate), which had eventually pooled on the sill. What is it with these cars and water? I want to just RTV the whole car, entry only available from the trunk! The leak is absolutely not coming from the regulator panel - I verified that with buckets of water.
So, it became obvious after additional tests that what I believe is called the water channels (aka waterproofing, water routing - the spongy, rubbery, black material that lines the edge of the rear doors), the seal with the door had started to develop small gaps. The other door is doing the same, although not as bad. I didn't really think about it before, but when you pull the channel back to expose the torx bolt (which releases the lock cartridge cap - allowing you to dislodge the external handle cable for regulator panel removal), you pretty much begin to break the seal. Over time, and repeatedly pulling on that area during door repairs, the seal gap extends. Heat and the elements start to develop other small gaps, and eventually you have enough openings that a significant amount of water can seep behind the water channels and into the side-of-the-door metal, which runs down to the sill. Obviously, this can eventually lead to a flood if you get enough rain in a small amount of time. Came pretty close to that yesterday, with tornadoes and horizontal rain coming through the area, so it was a good thing I was coincidentally looking for leaks from the newly installed panel.
So I'm curious if anyone has resealed these channels and, if so, with what sealant? I can't imagine many chemicals, glues, sealants will stick to the channel material. Perhaps flowable silicone, like I've used for the sunroof? Doubt it. I tried some of the GE silicone caulk, recommended by Andreas for the panels, but I kind of doubt that will work well. It's curing now, but I really think it will fail (if not immediately, in very near future), especially since I just tried to apply to the inside edge and push into the gaps. Maybe it could work if I pulled off the entire water channel, cleaned both surfaces, and applied a consistent bead and had a good way to apply pressure. Sounds like a PITA, but I want a solid fix and not have to worry about another flood.
Andreas mentioned that if actually replacing the channels, use the far superior OEM parts available via VW, ECS, etc (I think it's $60 or so) because the adhesive/sealant and material is much better than aftermarkets (ebay, etc). But, my channels are in excellent shape, minus the failing seal, so if there's any way to reseal them, that would be ideal. Just looking for ideas. Thanks.