Preserving the New Sill (1 Viewer)

[h82crash]

I have the quarters repaired and have the sill and sill cover fit up. The sill has some thin primer-like coating that scratches of pretty easily, so that has to go.

My question is how others have preserved the metal that is between parts. Like the sill, under the tub floor and sill cover? I have used weld-through primer in the past, but I'm not convinced the powdery coating actually prevents the parts from rusting. I have seen in restoration forums people have recommended epoxy primer and just removing it from the locations of the plug welds, not going to burn too much primer back from the welds?. How do fellow Mudders do it?

I blasted the inside of the new sill. Looks to be a prep problem with adhesion for the primer that came on it. It is really tough in many areas but flaked off in others. If it was done right it could have saved me a lot of work.

 

[rkymtnflyfisher]

I covered mine with a liberal layer of Monstaliner, then I shoot it once a year or so with black fluid film.

 

[h82crash]

I covered mine with a liberal layer of Monstaliner, then I shoot it once a year or so with black fluid film.

I'm trying to figure out what works prior to assembly. I certainly hope people are not welding the assemblies together bare (Toyota did and why they're all rusty), and trying to seal/paint later.

 

[rkymtnflyfisher]

During the rebuild of my rear sill I did use some copper-weld primer, I made sure I laid down a thick coat on everything I could.

After everything was done I paid special attention to the sill when I was laying down epoxy primer, then the single stage top coat.

Less than 24 hours later I was covering it all with Monstaliner.

Now I "maintain" it with the fluid film.

 

[macdaddy59]

I had mine galvanized before installation

 

[h82crash]

I had mine galvanized before installation

That sounds like it works. What did you do with the tub corners behind the sill?

 

[mrboatman]

Over 50 years old and done nothing and no rust at all. Just move to dry hot southern nevada and rust is not a problem

 

[3_puppies]

I had mine galvanized before installation

welding galvanized? need good ventilation for that,
how did you protect where the welds are?

 

[h82crash]

welding galvanized? need good ventilation for that,
how did you protect where the welds are?

The zinc will melt tight around the weld, unless you way overheat it. I'm more concerned where welds aren't. 1000 times more area than the welds. Welded galvanized for years, makes pretty smoke.

 

[Malleus]

Zinc phosphate is the gold standard for surface prep prior to paint. Less expensive is phosphoric acid wash. Both do the same thing: the outer layer is converted from iron oxide (which happens immediately after you remove all surface contamination from steel, chemically or mechanically) to iron phosphate, which is inert. A primer coat will seal against unwanted further chemical reactions. You do not need to use self-etching primer with either; any good primer will stick to the phosphate.

 

[h82crash]

Zinc phosphate is the gold standard for surface prep prior to paint. Less expensive is phosphoric acid wash. Both do the same thing: the outer layer is converted from iron oxide (which happens immediately after you remove all surface contamination from steel, chemically or mechanically) to iron phosphate, which is inert. A primer coat will seal against unwanted further chemical reactions. You do not need to use self-etching primer with either; any good primer will stick to the phosphate.

Tks. I've been treating the bare metal with phosphoric and wiping off. Specifically I was asking what coating they're applying to parts that get welded together restricting access to future coatings. Lots of weld through primers out there. Do they do a good job of rust prevention like they claim? On an abused area like the sill? I plan on using a 2k urethane primer. I know a little will burn back from the plug welds, but I won't super heat the area. I've seen photos of repair progress and it seems some people or shops just assemble the parts raw.

 

[macdaddy59]

3 puppies

I had the entire tub galvanized as well

 

[Malleus]

I know they're popular, but the weld thru primers are snake oil. No primer is going to survive the heat of welding, which melts base metal. That's why the OEMs don't use it. The best you can do for elements that will have faces inaccessible but exposed is to chemically treat it against corrosion, and then seal as best you can. That's all the OEMs do.

FWIW, that's why there are so many drains on landcruisers.

 

[h82crash]

I read Toyota requires using weld through primer on repairs. Funny that I haven't seen any real testing on the stuff. I have some that is 10+ years old and sprayed some 16 ga scrap with it. I think I'll do my own tests with it.

I think I'm at least 4 hours from anywhere that does galvanizing. I had to drive over an hour to get my frame powder coated.

 

[1MAC]

I use weld-thru primer wherever there would be bare metal hidden and the parts must be welded. For some things, welding isn’t really necessary. The little reinforcement plates under the seat brackets and jump seat bolts for example. For those, I epoxy prime the parts and use panel adhesive or regular epoxy to hold them in place. That way, there’s no bare metal anywhere. They are securely held in place with a nut and bolt anyway.

 

[Malleus]

That's been the OEM solution across the industry for the past 2 decades. I read somewhere the Audi A6 has more glue than weld (don't quote me on that, I may have made it up).

 

[Jim S.]

I just discovered 3M panel bond recently. It's good stuff !!!

 

[rkymtnflyfisher]

The Upol copper weld primer is legit. Definitely better than some of the others I used, SEM, Eastwood...

 

[h82crash]

The Upol copper weld primer is legit. Definitely better than some of the others I used, SEM, Eastwood...

I've read that the copper based stuff, while conductive and weldable doesn't have the protective qualities that the zinc based has. I have the Tempo brand and I don't even know if they still make it.

I found some testing and its interesting.