Roof rust

[larrie]

Am getting ready to attack the minor roof rust and wear points on the roof of our 2002 E350 EB with a CCV top. Have read through the threads talking about the process so think in know enough about how to do it.

I am confused about two steps;
1. What type of primer to use on the bare metal after using Por-15, acid etch or non acid etch.
2. Most of the rain gutter rust is over the rear doors. There is one small area over the passenger door. I am assuming that only need to remove the seam sealer where the rust is and leave the rest. Is this correct?

Herculiner will be the final coating.

Thanks for the help.

[arctictraveller]

I would use the manufactures recommended products.

https://www.eastwood.com/por15-gray-...ce=google&wv=4

First I would remove enough of the sealant to expose clean metal to assure you get all the rust that might be lurking under the sealant.

[E-350]

I just repainted my roof as part of the whole van repaint.

I sanded everything down to bare metal using 40 grit on a Da sander.
Then used bug and tar remover and applied 3 layers Raptor epoxy primer. Wit the leftover primer I additionally brushed the complete U shape of the rain gutter and filled all small cracks/ gap.
Wit the following 3 layers of Raptor I think I‘ll be well prepared.

The epoxy primer will also convert rust, see TDS of Raptor Epoxy Primer.

Removing the gutter seal stuff I used a chisel and wired brushed with an angle grinder. Worked really nice.

[Lilnuts2]

I just went through this. If you have any rust you need to take all of the sealant out and replace it. Once water gets under it in one place it can run completely underneath it and it's covered up you can't see the damage.

[SheepShagger]

Originally Posted by larrie

Am getting ready to attack the minor roof rust and wear points on the roof of our 2002 E350 EB with a CCV top. Have read through the threads talking about the process so think in know enough about how to do it.

I am confused about two steps;
1. What type of primer to use on the bare metal after using Por-15, acid etch or non acid etch.
2. Most of the rain gutter rust is over the rear doors. There is one small area over the passenger door. I am assuming that only need to remove the seam sealer where the rust is and leave the rest. Is this correct?

Herculiner will be the final coating.

Thanks for the help.

Personally I wouldn’t use por15 on anything that gets exposed so sunlight, and it makes for a terrible primer. So bad long term choice for this application, and even more so if your topcoat is bedliner. Use just about any rust removal / back to metal substance, then use a epoxy primer then bedliner. Remember no bedliner is fully waterproof so you will need a primer that is, hence I recommend epoxy primer. Personally I would also use 3M seam sealer to bring the gutter back to factory in between the primer and bedliner, but many don’t.

[Lilnuts2]

Remove all the gutter sealant! Get a wire wheel on a body grinder, prime with epoxy primer, as said above use 3m gutter sealant, and paint or bedliner, not Por15 it does not like sun and will fog and fade quickly.
Don't take short cuts on this, I can Guarantee if you have rust in some area you will have hidden rust elsewhere.

[larrie]

I started the rust repair today and found some nasty areas over the rear passenger side door. The rest of the drip rail looks much better.

Is the correct fix to do the following steps? Are there other better ways to do the fix?
1. Grind out rust
2. Remove all lose material
3. Apply Por-15
4. Fill openings with bondo
5. Apply primer
6. Apply Herculiner

[E-350]

I would say yes. But if you have any chance I‘d also try to check from the inside. On the pic it looks like water could have flown in. Now you might seal it up and it further corrodes inside.

My gutter (by far) didn‘t look as bad, but I did the following:
Sanding via wheel/ angle grinder with 60-80 grit
Cleaning it up with bug/ tar remover
3 layers epoxy primer (also neutralized last bits of rust) (With the leftover paint I used a smaller brush to get it into all cracks/ corner/ gaps where the spray didn‘t get to)
3 layers Raptor

[SheepShagger]

That's not a bondo fix, that's a cut out the rust and weld in a small piece of sheet metal, grind the welds, then maybe bondo to smooth out the lines. It's actually super simple to do in that area.
Id also check you don't have any pin holes in the actual trip rail, with that amount of rust on the body you may have. If so, simply make the plate a little larger that you weld in.

Personally I wouldn't use POR-15 on that, there are way better alternatives. Since you are using primer and Herculiner, use your preferred form of "rust stabilizer or rust remover" over POR 15. It's far cheaper and will work better.
POR 15 is great for rust on frames / undercarriage components and such, it's terrible for bodywork or anything you want a decent finish or UV protection and it's a terrible primer, as very little adheres to it well.