Best way to handle this rust? (Paint Prep)
 

Hi Guys,

I have been restoring this old 1987 F150.
I have put in 4 floor weld patches, both fenders and reconstructed both cab corners.

So when ever I saw rust, I just cut it all out and welded a patch.

But I removed a fiber glass visor from the roof and found this rust...
Its SOOOO close to the Windshield and I dont think I can get good metal along the windshield edge to weld to.
I am going to bring it to a paint shop to get it done professionally, but I need to know how to prep this so that the paint lasts for years.

This is the most worrying, since its so close to the windshield.
https://i.imgur.com/ZhoEtus.jpg
https://i.imgur.com/jd1ddCa.jpg

But there is also rust in the corners of the door frame. So same question, is there a way I can keep from cutting all this out?
https://i.imgur.com/2rxxXNZ.jpg

Can I sand the surface, put OSPHO on it until its all black and then put body putty over it?
If not, what do you suggest?

thanks!

Denis

No one has any suggestions for me? Is it that bad? :-P

I would have the areas blasted with walnut shells (less damaging). Then dimple down the area around the holes, then apply your OSPHO. Then putty smooth, paint your favorite color.

Are you planning on stripping the whole cab?

The problem overcoating unknown top coats, is your new paint is only going to adhere as good as what’s under it.. If that topcoat is sound,, it needs to be completely sealed before a fresh application of finish..

Looking at the drip rails, under the sealer looks to be blistering as well. What’s it look like in the windshield channel? If the plan is to strip, or partially in many areas, taking the glass out isn’t too difficult.
Media blasting to a clean base, would be your best bet as to no future surprise blistering in all those areas.
Torch welding, out of the question near the glass.. It’s possible to carefully mig stitch weld up fairly close to glass if precautions are taken, meaning completely protected from weld spatter and cooling materials added for heat transfer where it’s not welcome. Too hot and the glass sealer is compromised.

If mig stitched, adding a stitch or two, quickly cooled to stop the heat transfer, then stitch, repeat, during the full patch process.. But hard to tell the condition of window channel itself. Meaning, if the face of the channel is completely sound, you could cut behind the channel into roof panel and put the patch leg behind the channel and stitch it in on its leading edge. Still a butt weld of sorts, but more an overlap so less chance of weld drop through. The trick, is it must be clean metal, otherwise the risk of welding pop, or blow outs/drop outs leaving more or larger holes.....

If the rust is only to the roof panel edge, doable, but if it extends down into the channel, I’d pull the glass. Actually I’d pull the glass in most cases just to get epoxy prime/paint into the channel/ pinch face.

I’m not one for filler patches, but ok, who hasn’t done them.. If that’s the option, I’d use a metalized filler, or glass reinforced.. But they must be over clean sound bases. The other option (more so over any holes) may be cold patches using structural adhesives. Or a combo of both...
We used to have to repair quite a few roof top and post mount ‘large’ antenna holes, cracks from, and with the headliners in,, welding was out. We used a metal patch either on top, or from under with a structural adhesive, and would rivet them as well. A good reinforced filler, then usually a skim of a standard filler..