Treating rusty original floor pans

[thegreatjustino]

Some of you know I'm the second owner of a very original lifelong California Bronco. When it underwent a minor restoration back in 1992, the only rust was on the front floor pans. The driver side was worse than the passenger side and the crease going up toward the firewall was fiberglassed to address the worst of the rust issue. At some point these are going to need to be replaced, but I'd like to put that off as long as possible. I don't know what the brown paint/primer/treatment material is, but I assume that was done to combat the rust back in 1992.

I've thought about treating the rust you can currently see with naval jelly, but I've never actually used that product.

Looking at the photos below, what would be the best way to treat this to put off replacing the floor pans as long as possible? They're still pretty solid and other than the fiberglassed over area, there aren't any holes rusted through, so I should be able to get quite a bit of time out of these with some kind of treatment I would think.

 

[Jdgephar]

Clean it up with a wire wheel and cover it in some por-15. That's my vote.

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[DirtDonk]

I used naval jelly on my floors and kick panels when I first got my 71. Just happened to have it around and thought I’d give it a try.
I couldn’t tell it was doing anything because there were no major changes in appearance, but it definitely stopped the rust from creeping.
I didn’t even cut it all out, though I did try to trim a bit off before I treated.

It’s also possible that the reason it stopped creeping was because the Bronco was now in the dryer CA environment, but I always thought the naval jelly helped.

 

[hsach]

Clean it up with a wire wheel and cover it in some por-15. That's my vote.

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This is what I would do, except use Rust Bullet. Same as Por-15, it is just what I have been using.

I usually hit it with Rust Blast or similar metal prep just before the Rust Bullet/Por-15 also.

 

[ba123]

I'm not sure how it would do on a floor since you need to wash it out but I recently used this stuff on a could parts called Metal Rescue Rust Remover Gel and it is awesome! Totally biodegradable, you just wash it off after it sits and turns your rust to nothing. Granted, it won't put back the metal that's been eaten away but something to think about to get rid of a good amount of it if you are able to wash it off. The couple parts I did, I washed, rinsed, towel dried and then used a heat gun.

Here is my before and after of my brake pedal assembly that day outside for a while… I did use one more application after this pic before I painted it but I did zero prep. Just brushed the stuff on and wrapped it up and left it until the next day.

 

[trailerjack]

Id wire wheel it, ospho it, prime it and maybe change out those body mount bolts if possible while there is still something to remove....but that may open up a can of worms!

 

[m_m70]

Id wire wheel it, ospho it, prime it

This worked well for me on my rear inners with surface rust. Been about 8 years or so and nothing has come back or spread.

 

[tirewater]

Leave it alone? Once you start working on it you may find that there's more damage than expected.

I'd recommend something less aggressive than a wire wheel. The metal is going to be pretty thin in places and the wire wheel will start poking holes in it.

I'd start with a sanding disk, 80-120 grit, to knock down the high spots and bubbles that are visible. If the sanding disk is too aggressive you can go to a higher grit. Underneath will be pits.

If it were me, I'd try to build a dam along the edge and pour a gallon or two of Evaporust into the footwell, toss some plastic over it so it doesn't evaporate and let it sit a week. I've used Evaporust on a lot of smaller items such as exhaust manifolds, and have been pleased with the results. It's much easier and safer to use than Phosphoric acid products. Drawbacks are it's slower, and item with rust needs to be constantly wetted with it. The problem with the footwell, is it probably isn't water proof, and any rust that goes all the way through the metal will be dissolved causing a hole.

Or you can use whatever your favorite phosphoric acid product you want (ospho, navel jelly, etc...). I'm not big fan of the gel type phosphoric acid products as I have left them on too long and it becomes a pain to clean the residue off. For deeper pits it'll require multiple applications of the product.

You can try the gel versions of evapo-rust or the Metal Rescue Rust Remover. I haven't had much luck with Evapo-rust gel - it's messy and doesn't appear to do much.

Once you have the pits treated, you can apply a urethane sealing product like por15 or master series to inhibit the rust from spreading. After that, you'll probably still have pits that you could use filler/bondo to level out - then apply a top coat.

 

[bmc69]

Another regular Ospho user here. Very effective for "killing" rust and making it an inert coating to which pain can be applied.