Seam sealer question

[gears]

Ok, not a tractor but I'm straightening a damaged cab (1st gen Dakota) and the firewall seam on the passenger side was caved in and the seams buckled enough that it was getting heavy rain water incursion. I've straightened it out (Go Go Port-o-Power) and scraped the foamy looking sealer off.

It is in factory primer and I plan on coating everything internal and underside in Rustoelum industrial enamel before Fluid-Film undercoating.

Several seam sealer questions:
1.) Put it directly on the primer and then top-coat with the rustoleum?

2.) should I spot weld these seams 1st or leave them as found (factory crimp)?

3.) should I just enamel everything and then seal it and then the FF?

 

[showcrop]

That foam sealer doesn't impress me. Anyway I re-applied here and there where needed, and where I had seams completely apart, I plug welded them back together. I then injected phosphoric acid in between the pieces, just in case there was any rust, Then primed with epoxy primer. I then pressed the butyl seam sealer in place, then top coated with my base coat-clear coat. I had no need for the Fluid Film, because I have continuous paint film.

 

[gears]

Thanks Show, I'm using the Ospho before paint. As this is being buried behind multiple panels, I want it suitably coated. I will paint over the sealer once it's done.

 

[lodoc]

I prefer the 3M urethane sealants for automotive restoration seams. They stick well to about any surface whether primed, painted or bare metal as long as it's clean / free of grease, oil, etc., and are paintable. You can get them in squeeze or caulk gun tubes or brushable can. Spot welding probably not necessary if you have it 'pulled' close to where it should be and it's not structural.

 

[gears]

Thank you doc. Port-a-power on the inside, tried a slide hammer to no avail from the outside so I chained a 600lb ATV to it and used that to yank the hinge mount pillar back out the 1/4"...
I will source some 3M Urethane.