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Sealing of Joint Between Cap and Top of Van

Posted: Tue Nov 06, 2018 11:59 pm
by Jazzy
Hello, I am cross-posting this on the various Airstream/B190 forums, so I apologize in advance for the redundant posts and message length.

We have noticed a potential source for a small leak into the back right corner of our newly-acquired B190. (See photos for context).

Questions: (1) Does anyone have any recommendations on what sealer to use between the B190 cap and the top of the van, and how to do the sealing in this area? (2) Is it possible/advisable to apply a sealant around the perimeter of the joint, or is this not advised (should we just seal the isolated problem area?)

Details: The culprit seems to be an area where the bottom of the top cap/hull meets the top of the van (as shown in photos). We think the water must come from the described joint area because the water "rolls down" the inside of the back door and also touches slightly into an area/corner of the wardrobe closest to the back door. The back door window seals look fine to us. There is no apparent water coming from the bathroom fan. I don't think the origin is the toilet vent because there is no water inside other parts of the wardrobe or in the bathroom, and there are no other signs of water anywhere else inside the B.

I have read info. on the forums about various sealants applied for different purposes, but I have not been able to locate a sealant for this particular purpose in any post (I am listing some below). Because the junction touches on fiberglass and metal, both, I want to make sure I prep the area properly and use the right sealer. I also do not want to "overseal" and cause water to accumulate under the sealant placed in this joint area (I remember reading a post stating this had happened to someone else who used putty and the putty caused water to pool in the area.)

Potential Solutions: Some sealants I have read about include Sikaflex 221 White or 715.

* Sikaflex 221 White (for roof seams, seals and bonds. The post I read recommends using Eternabond spray cleaner to prepare surface)
* Sikaflex 715 (used around fans, vents, skylights ... self-leveling)

Any feedback offered on this subject is much appreciated!!

*****

Update 11/8
This morning I did force some water down the top of the door, and it showed a small leak, pointing to the source being the door's weatherstripping, after all. However, we still need to fix the crack up above. Someone in another forum recommended Lexel. Someone else, 3M 5200 Marine Sealant.

Re: Sealing of Joint Between Cap and Top of Van

Posted: Thu Nov 08, 2018 5:30 pm
by DavidP
is the first photo of the outside?

Re: Sealing of Joint Between Cap and Top of Van

Posted: Thu Nov 08, 2018 5:38 pm
by Jazzy
Hi, Yes. It is of the outside. I am attaching a side view for clarity.

I updated the post above with the following:

Update 11/8
This morning I did force some water down the top of the door and it showed a small leak, pointing to the source being the door's weatherstripping, after all. However, we still need to fix the crack up above. Someone in another forum recommended Lexel. Someone else 3M 5200 Marine Sealant.

Re: Sealing of Joint Between Cap and Top of Van

Posted: Fri Nov 09, 2018 11:27 am
by usachris
I had to replace the rear door weatherstripping as well on my 1999. Maybe 20 years is the limit for that particular rubber seal. :roll:

Re: Sealing of Joint Between Cap and Top of Van

Posted: Fri Nov 09, 2018 12:20 pm
by Jazzy
USAChris, They looked pretty good, so we thought they had been changed already, but I guess not... :mrgreen:

BTW - What do you do to maintain that upper hull to van joint area I am worried about, if anything?