I bought a 1973 Dodge van for cheap. It's got a big ol' 5.9L (360ci) V8 and can tow my other cars on a trailer. Which is all fine and dandy. Except the roof is rusted to all heck. The middle and top of the roof is fine. The sides, where it connects to the body, have rusted through. Basically, only the roof beams are keeping the roof attached to the van. Needless to say, it leaks a fair amount and I'm going to be getting some rain soon.

I'm just interested in a quick and dirty fix so I'm going to just fill the backside of the roof with expanding foam. Then sand, seal (somehow), prime and paint.

Here's what I'm working with:



Any warnings, encouragement, or other cheap ideas for a fix?

 

Expanding foam will not handle the vibration and movement of the metal panels. I suspect it will start falling apart within days. My suggestion for a cheap and quick fix is a roll of flashing. You can buy a roll of 4"-6" wide flashing at a place like home depot along with a couple of tubes of silicone, and a couple packs of rivets or self tapping screws. Surround your rusted out areas with the silicone, plus a little space for the screw/rivet penetrations. Roll the flashing out and attach it to the roof. Once you're done, a quick coat of Rustoleum should hold you over for a while.

 

Went home on my lunch break and filled one side of the roof "shelf" with foam. Says it'll be completely dry in 4 hours -- we'll see. I only did one side (the side that wasn't in horrible shape) because the wiring harness runs down the driver's side and I've got a short somewhere in there I want to take care of before filling the cavity.

 

Hmm, flashing + rivets sounds like a very good idea. I'll see how this stuff holds up for a few days and if it looks like there'll be problems, I'll try your idea. I'm hoping that the foam will provide enough support that the roof doesn't vibrate much (and thus, doesn't destroy the foam). Time will tell....

I used regular expanding foam for this side. I think I'll stop by a boat store and pick up some marine foam for the other side (where it has rusted completely through). I've still got a few tubes of silicon sealer if I need to use that on the flashing.

 

FYI - a hacksaw blade is the best thing to use for trimming once the foam is dry.

 

I figured the heck with it and foamed up the other side as well. It'll be dry in about 3 hours. Tomorrow, I'll take it out for a spin and see how it's treating me.

Total cost so far: $10.98 for 2 cans of foam.

Anybody have experience with the UV-hardening fiberglass things like Solarez? I was thinking about putting a layer of that over the foam.

 

Solarez (Polyester based resin) would not only be very expensive for the amount you would need, but there is a chance it will dissolve the foam. Solarez had chopped fiberglass inside of it and does not fair out smoothly.

Epoxy Resins versus polyester resins will bond much better with roughed up metal, but Epoxy is more heat sensitive, and damaged more easily by UV light. There are also secondary bonding issues possible depending on the type of epoxy. (Amine blush).

Now you could cut out some rectangular strips of thick 10 oz cloth, about 4 feet long 5 inches wide, saturate them with epoxy on top of a piece of cardboard, and lift off the cardboard and lay them in place then squeegee them plat to conform to the roof

If you have not worked with fiberglass before, It will drive you nuts. It must be sanded and painted.

There is a product out there. I am not sure what it is called. It comes on a roll. It is about 3/32 of an inch thick. Once side is a soft sticky adhesive rubber. The other side is an aluminum skin. Using a roller, this can conform nicely to curves and bends.


There is another Product out there made to repair the rubber roofs on RV's.
Eternabond tape. 10 year guarantee. Comes in black and white. I think it is like 68$ for a 25 foot roll 4 inches wide. Providing the surface is totally clean when applied, it will never come off.

 

Eternabond isn't just for rubber RV roofs, it's used on metal RV roofs as well (like mine). Stuff is stickier than heck...it's a really good bond.

The other stuff is butyl tape, used mostly in HVAC applications. It also works really well.

 

Here's the driver's side (the bad one) with foam spilling out. Keep in mind, this was sprayed from the inside.





Thanks for all the suggestions. Some of those sound pretty promising. I've got a few rolls of duct insulation in my garage, i think that is the same as the butyl tape stuff.

But that Eternabond stuff sounds nigh on perfect. Too bad it's a little pricey for this project ($68 is almost 1/4 the purchase price of my entire van).

Any thoughts on Gorilla Tape? I haven't used it myself but I've had good luck with Gorilla Glue and heard nothing but positive reviews of the tape. Unfortunately it's only 2" wide so I'd have to overlap layers it to get good contact in some spots.

 

It doesn't hold up very long when exposed to moisture for any extended period of time.