Rust Has Invaded The Roof! What To Do?

[AcesHigh]

Hi everyone, I just bought a 1970 521 less than a month ago and after doing the mechanical work, its time for some body work. There was some surface rust on the roof so I removed the paint and found bondo; When I removed the bondo, here is what I found:

 

 

From my understanding, it will need to be cut out and have a new piece welded in. The body shop nearby said there is a 2" copper seam that runs from the windshield to the edge, and they would have to cut a few inches below the seam. If I pull the windshield and headliner, he'd charge 500. I don't have 500, let alone 300..

 

My question is: Can I use naval jelly to remove the rust, use acetone, rust neutralizer, short-strand fiberglass filler, and epoxy primer? Would the rust neutralizer prevent the rust from spreading? Thank you for your help on this.

[Zeusimo]

Kill A Man

Rob A Bank

Get $500

Get It Done Once

The Right Way

[AcesHigh]

"Get it done once, the right way" -words of wisdom. If this was a '95 civic I could care less, but in the short time I've known about these trucks, they're disappearing and I don't have it in me to put a death-sentence on it.

[q-tip]

Mini truck style targa top!!!!

[INDY510]

.

Grinder/Wirebrush and fiberglass filler might last a few years($20) .. or cut out a big hole/weld new metal might last a few years($500)

 

looking at the rust/bondo around the windshield weather stripping, I'd say that's a perfect canidate for a cheap fiberglass filler fix, there's probably alot more hidden rust... save up the $500 for your own welder

[metalmonkey47]

^^Indy tells the truth.

 

 

Look over craigslist for a used welder cheap. Also, Home Depot rents out nice Lincoln Electric welders for about $45 a day last time I looked.

 

 

If the rust is bad there, just wait until you look over the rest of the body. You're gonna need a welder.

[datzenmike]

Rust is not like cancer, it only spreads if you let it. If you can seal water out and the oxygen in the air from getting to it, it stays put. Grind it out to bare fresh metal, weld the hole shut (doesn't have to be great, only solid, no holes) so nothing can get to it from behind and it has support. Thin layer of bondo or w/e, sand to shape, primer and PAINT to seal water and air out from the top. Spray can primer is not the same thing.

[DanielC]

There is a lot of good advise in this thread, but some of it may not be practicable to you. Yes, cutting out,and removing all the old, damaged, and rusted metal, and wending new clean metal is the "right" way to go. You are getting advise to just buy a welder, and fix it. Well the welder is just the beginning. You also need grinders, body hammers, dollies, and a whole lot of other tools, and supplies to "just weld in a new patch panel" Never mind you learning to weld, and having space to do it.

 

First, if is was me, strip the whole roof, and probably remove the windshield. The weather strip for the windshields is probably not in the best of shape, and in order to save the windshield, your best bet is to cut the weather strip. wayno on this forum may have new weatherstrip for the windshield. Send him a PM, if you go that route. He is also a pretty good welder, he can give you advise on that part of the project.

Evaluate the cab you have carefully. Look for rust up under the cowl, under the dashboard, the floors, around the battery tray. the whole cab. Also, start looking for another cab, if you decide this cab is not salvageable. Check the other cab as well. You found out damage,,and rust can be hidden under paint and plastic filler.

 

So this is what the roof on my project 521 looked like, when I got it.

There was a rectangular steel plate in the center of the roof covering these holes.

After cleaning and sanding the roof down to bare metal, it was primed with a rust inhibiting wash primer, PPG 1791/1792, and then with PPG DPLF epoxy primer. After the epoxy primer had set for a day, I then used Fiberglas mat, and roving and marine epoxy resin to cover the holes. Marine grade epoxy resin from Tap Plastics. This page. 314 resin, 102 hardener.

http://www.tapplasti...epoxy_system/27

Once that was cured, and sanded, plastic body filler, high build primer, and finally paint.

My roof now.

[Skib]

its perfectly ok to wire wheel the rust. prep the surface properly and use fiberglass filler.

[INDY510]

There is a lot of good advise in this thread, but some of it may not be practicable to you. Yes, cutting out,and removing all the old, damaged, and rusted metal, and wending new clean metal is the "right" way to go. You are getting advise to just buy a welder, and fix it. Well the welder is just the beginning. You also need grinders, body hammers, dollies, and a whole lot of other tools, and supplies to "just weld in a new patch panel" Never mind you learning to weld, and having space to do it.

 

not many people are skilled enough to fix this the "right" way .. doing a shitty job of welding in the patch panel will make the cab scrap metal in a few years,,, while fiberglass filler might last longer than that, and still be fixable later

 

 

Rust is not like cancer, it only spreads if you let it. If you can seal water out and the oxygen in the air from getting to it, it stays put. Grind it out to bare fresh metal, weld the hole shut (doesn't have to be great, only solid, no holes) so nothing can get to it from behind and it has support. Thin layer of bondo or w/e, sand to shape, primer and PAINT to seal water and air out from the top. Spray can primer is not the same thing.

 

ALL Datsuns are already rusting from the inside, there's really no "right" way to fully seal your welds from the inside of a rocker panel or roof . likely the welds will rust out from the inside, and then you will have a HUGE hole in your roof.. wirebrush/grind fiber-filler DONE

[bananahamuck]

Navel jelly is like the old way of doing it ,,,try a auto paint store and use a newer formulation type that does basically the same thing but you dont have to wash it off ,, the kinda you can paint directly over.

[INDY510]

.

Like OSPHO?

[BJW's FiveTen's]

Ospho rules!

Also you can find it at many hardware stores.

[AcesHigh]

 

After cleaning and sanding the roof down to bare metal, it was primed with a rust inhibiting wash primer, PPG 1791/1792, and then with PPG DPLF epoxy primer. After the epoxy primer had set for a day, I then used Fiberglas mat, and roving and marine epoxy resin to cover the holes. Marine grade epoxy resin from Tap Plastics. This page. 314 resin, 102 hardener.

http://www.tapplasti...epoxy_system/27

Once that was cured, and sanded, plastic body filler, high build primer, and finally paint.

 

Thanks everyone for your help with this! 2 quick questions: Why use the rust inhibiting wash primer, PPG 1791/1792? Does it neutralize the acid? I ask because from what I've read, Epoxy primer seals out the moisture.

[DanielC]

With any paint product you use, read the data sheet. If the metal is clean, and has NOT had a acid treatment on it, use the 1791/1792. The data sheet on DPLF says adhesion can be improved by using a conversion coating. A conversion coating is a phosphoric acid treatment. The safest way to go is to use is to use PPG's version of a phosphoric acid. It is more expensive per quart than Ospho, but you dilute it down before you use it.

All the above is for the very last step before you start painting primer, whatever primer you use.

 

For rust removal, almost any phosphoric acid treatment would work. I have used Dupont's metal conditioner, PPG's version of the same stuff, Ospho, and Naval jelly. I use the products with steel wool, and scrub. In between scrubbing I use Dawn dishwashing detergent, and paper towels, to clean the metal to see where I an as far as removing the rust. I have also used some tooth brush sized stainless steel bristle brushed to get into small areas, to remove rust.

 

I had some trouble finding Ospho. I finally found it in a Wilco store here in Oregon. Wilco stores are kind of a general store that cater to farmers, ranchers, and people who have a few acres of land and think they are farmers or ranchers.

[tr8er]

POR15 is amazing. And perfect for this kinda stuff. Make sure you paint over it, and dont use anything you would prefer to keep when applying. It will ruin any brush. But it will also ruin rust. Just be sure to get at the rust from BOTH sides.