water leak

[stuart1]

Hello All, I noticed a wet carpet opposite an exterior seam of the skin. Can anyone recommend an exterior sealant to seal the seam? Also, I've unskinned the inside wall (to repair a broken wire) so I will be able seal the inside as well as the outside seams.
I took some pictures of the opened wall just in case it will be helpful to someone and will try to attach the pictures (a new feat for me, so time will tell if they get thru!)
Thanks, Stuart

[stuart1]

Ok, I guess the picture didn't find its way thru the computer maze, so here's another try?

[thenewkid64]

Vulcem on the inside and par bond on the outside. Or you could use vulcem on both but you will either need a syringe or masking tape to do it neatly on the outside.

Have you tested with a hose to be sure this is where the water is coming in?

[stuart1]

Bret, yes, I watered it and found the seam was leaking at and below the window level so I think it best to seal the entire seam. I could also see a few small areas, 1/2" to 2" in length, where the seams had seperated, leaving a very small gap.
Will I be able to find both the Vulcom and the par bond (is that the brand name?) at my local RV supply shop?
Thanks for the tips, Stu

[thenewkid64]

It depends, Some places stock it some don't. If they sell Airstreams they will usally have it. If you can not find it locally you could try either Airstream Dreams or Inland RV. Both will ship it to you.

From the Airstream Dreams website:

There has been some confusion regarding which type of Vulkem to use on the repair of Airstream trailers. Tremco, the maker of Vulkem, manufacturers more than a dozen different types of Vulkem. It can get confusing, so here are the facts:

Vulkem 116 is the old standard. Airstream restorers have used it for years. Vulkem 116 is IDENTICAL to Vulkem 616. The numbering system is used by Tremco as a way to track sales only. 116 is sold through building trade suppliers. 616 is sold through industrial suppliers, like those who sell to trailer manufacturers. They are both "textured" (sort of grainy). Anyone who has used 116/616 will know what this means. It isn't a big deal, but you may notice the difference in the finished look if you look closely.

Vulkem 631 is IDENTICAL to 116/616 except it comes in different colors. A Tremco representative said the name change is done for marketing reasons only.

Airstream no longer uses 116/616/631 in the production of new trailers in places where it will show because of the texture. They still use it between panels before riveting them together. They are now using Sikaflex 221 in areas around vents, hatches and windows where it will show because it is non-textured. It is also more expensive and even more difficult to find than Vulkem.

Because of the texture, Tremco does not recommend Vulkem 116/616/631 for the restoration of old Airstreams. Instead, they recommend Vulkem 636. Vulkem 636, like 116/616/631 is a premium slow-cure polyurethane sealant. Slow curing is important because the slower the cure, the higher the ratio of solvents to solids. The solvents are useful in cutting through any oil/grease that may be on the skin of the trailer. This gives better adhesion on aluminum that has been exposed to the elements. Fast-cure sealants like TremPro 650 (another similar product) are used in assembly-line production where material conditions are controlled and speed is important. Also, slower curing sealants are generally stronger than faster curing sealants.

Besides a slightly slower cure than 116/616/631, 636 has the singular advantage of being non-textured. If you see a product called Vulkem 626, you should know it is identical to 636 except that it is textured. Vulkem 636 is the ideal sealant for Airstream restoration, whether used in visible or nonvisible areas.

Here are excerpts from Tremco descriptions of 636: "Vulkem 636 is specially designed for use in the joints of vehicles such as trucks, containers, mobile homes, recreational vehicles, rail cars and similar items where the joints are subjected to stress and vibration as well as expansion and contraction...Once cured, Vulkem 636 exhibits tenacious adhesion and has the ability to be subjected to stress and vibration as well as expansion and contraction within a joint... Vulkem 636 is especially effective in holding roof sheets in place against normal load vibration and air forces...Rivets may be set through the uncured Vulkem 636, which will act as a sealer."

I know TMI, but it is good info to have.

[stuart1]

Thanks! TMI? Perhaps but I always try to print TMIs because, more times than not, they come in useful down a lonely road. This TMI has now gone into my TMI folder and I'm off to the MPS to find some 636. Happy trail 2U, hopefully our paths will X B4 2 long...Stu

[Glue guy]

I realize that it's been a few years since this thread started, but Bostik makes some great products for these applications also. Their Liquid Rivet product is great for doing sidewall repairs and the like. They also make a product called 2175FS that has much better UV resistance than the Tremco polyurethanes. Also the chemistry allows for a more continuous cured bead, as opposed to the Tremco (and any other) polyurethanes that form bubbles inside the bead.

Good luck!

[Glue guy]

Forgot to mention that these products can be bought at Chembar.

Good luck (again)!