RV Repair: leaking roof, seam sealer, gmc van

Question
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Followup To
Question - I should have told you in the 1st note. This van has one piece full walls and one piece full ceiling panels with wood trim and built in lightening. the wall panels went in before the ceiling panel. In the 70s I used to do van parts so I am familiar with this, it would take me probably a week to take it apart and put it back. So I dont have any way of seeing where the leak is coming from other than its the roof and other than the gutter area it all one panel. So it must be that area leaking. I gues what I am asking is what material could I coat this area around the van roof with ? That will be long term and can go over the 3 M seam sealer I already used ?
Thanks again for your help.          Mike
  
please help,

I have a real problem that I cant seem to fix.

I have a 1993 Gmc van that has a gutter

area all around the roof formed by a factory

seem where the roof and side panels meet.

This conversion van has been stored in a

garage all its life before I got it- 32000 miles.

The seam inside this gutter like area all

around the roof was not sealed at the

factory. I ve had several of these and they

are solid filled in this area, this one wasnt at all you could see all down inside where they met.

So I bought some

3 m factory seam sealer and went around the

whole roofs edge where it meets the side

panels all around the whole roof. Well here in

Florida it has developed some cracks in the

seam sealer, but it has been in the garage

and the other day I took it out in the rain and

the whole back half of the trucks interior was

wringing wet - water even running down the

side wall like a water fall. This is going to ruin

a perfect van that I like very much. Can you

guys recommend a material I can go around

that 6 inch wide area all the way around the

roof that will seal this thing before the whole

interior is destroyed ? Being handicapped this

old van is my "55 Chevy" and I really need to

fix this.
Any help would be really appreciated. thanks

Mike Sarasota Fl.      archindustries@comcast.net


Answer -
The first thing you need to do is find out exactly where the leak is coming from. I seriously doubt whether you actually need to seal a 6" area all the way around the roof. Have someone run a garden hose on the van whaile someone is inside and determine where it is coming from.
You should be able to seal it up with a couple of tubes of clear silicone sealant. It's hard for me to give you a complete answer without actually being able to see the van, but give this a try. I wouldn't be surprised to find that the original sealant has dried up and cracked. If it is original from '93, that could be the problem.
Dave

Answer
I don't know for sure, but it sounds like you have to cover a fairly large area. You might be able to use the lap sealant that they use on RV rubber roofs. That would probably do the trick. You can get tubes of it at RV supply stores. It may also come in 1 gallon cans. You would need to make sure it sticks properly by testing a small area first. Also, it is white, if that makes a difference.
Dave