the drip edge on the edge of my roof is rusting on my 91 ctd, what can i do to prevent it anymore? i don't see where or how it's rusting??? 3 or 4 years ago there were some bubbles i sanded it down with my da sander and applied 2 coats of POR 15 and now the rust is back. why do the dodges rust there and what can be done to prevent it. my other 91 did the same thing and the drip edge completely blew off going down the highway!!!

 

Buy some Corroless paint, Eastwood Company sells at as "Eastwood Rust Encapsulator". Rust won't advance past it at all.

 

Not too long ago, someone posted before and after pictures where they had rebuilt the drip-rail.

Myself, I would bore some access holes from inside the cab and flood the cavity with whatever rust-killer I liked, raising the rear of the truck as high as possible, or parking it nose-down on a steep bank, when doing this.

Then, I would wire-brush away all of the exterior rust, cover all surrounding areas with Rust Bullet, prime and paint, just cutting away the rusted drip-rail.

Then, I would HIDE the damage with a LUND cab-visor.

 

In reality it is rusting from the inside out. The only near permanent fix is to find a good replacement roof section and treat the area that rusts with a rust converter and a good grease based undercoating or an anti rust coating before you install it. This is one of those deals where the cost of the fix is proportional to the overall life expectancy of the repair.