Sealant between Cabover fiberglass shell and the roof of the Ford E350 Class C Motorhome?

[Robert WiLLbanks]

Hello,  I am researching a replacement caulk for my newly acquired  1992 Champion Chase Commander.  I am into a 5 week repair and upgrade job on this unit. Pictures to follow. Because the bond has broken with the OEM sealant over the cab,there is water intrusion over the windshield and door.  Do any of you know what type of sealant was used originally to close the joint between bulbous fiberglass shell and the Ford E350 body.   Gotta say, where the sealant is still attached, it is very difficult to get it to release. It require q very sharp knife to separate the bonded surfaces.  I would appreciate any assistance you have to offer.

Buoyantly

Professorbob.

[Rich Thomas]

I'm going to garner a guess Robert and say it's probably a poly based product. silicone isn't a very good product for RV, Motor Homes or campers in general. A very clean surface is KEY to a good bond and you can find very good polyurethane materials at LOWE'S, HOME DEPOT, and other big box stores. also any RV dealership should be able to supply you as well although probably at a higher cost. When I done my roof, My local RV place that happens to be fairly up front told me they used loc-tight products bought at Home Depot for the projects they do in there own shop. Any way I'm sorry I can't give you specific product names but you should be able to find a suitable material. good luck and stay away from silicone based material you will just be doing it again in short order.    

[Robert WiLLbanks]

Rich, Thanks for the rapid reply. Yes, I know about silicone. Regardless of what is advertised as its adhesive qualities, it should only be use for purposed for which it is designed. It was used in the strand board sub floor in several areas to fill gaps around the wiring and plumbing. Worked seal, but not hard to pull out where necessary.  Just need to find a caulk that resist flowing out of the seam before it sets. I too think polyurethane is going to be my best bet. Just trying to use the resources here for other member experiences.

Thanks again for the reply.  I will be posting a photo log once the project is finished. Buoyantly Professorbob

[Rich Thomas]

Sickaflex makes a non flowing sealant. I used it on the side seams on my motor home. I don't know why I didn't recall it on my first reply; I think it was Sickaflex 221. It's a white stiff but flexible material and it's a bit expensive but it worked well for me.  

[Russell E Johnson]

Another good sealant is dicor they make both a self leveling and a non leveling caulk.  I carry both in my MH for emergency patches and the non leveling stays  where it is put without the problems of silicone.