So a few months ago, I discovered that the floor mat of my 2003 Ford Ranger Edge wasn't attached firmly down to the the floor and some dirt had accumulated under it. I finally got the time to clean it out tonight and when I lifted it up to vacuum it out, I found that a bunch of rust has formed. It's pretty deep rust too, that has begun to undermine the seam sealer on the body. The whole floor mat setup is bizarre too. I have no clue weather it's stock or some weird aftermarket thing, but it's got a top layer of plastic/rubber (basically the floor mat itself) and then a chunk of material that is similar to carpet padding, then a stiff rubber material under that that is somewhat brittle now, and finally the metal floor under that. the top rubber piece doesn't seem to be making a very good seal around the edge near the door, and I suspect water is getting under it anytime that I get in our out. I also am perplexed by the fact that holes have been drilled through the floor top rubber floor mat, and then through the metal floor of the truck. So now I'm concerned that water is getting up through there too.

I've attached some pictures of it's current state, and that should give you a better idea of exactly what I'm dealing with.

So basically, my questions is this: I want to repair the rust and keep any new rust from forming. But how should I go about that? My first thought was to just calk around under the mat and then get some screws to hold it down, but now I'm thinking that it needs some paint as well. I'm also concerned that the different layers of material in there are trapping water against the bottom of the floor when it gets wet, and making the rust issue even worse. But to take all of it up and replace it is a massive undertaking, and I'd love to avoid that if I can. So any input on how to fix and rustproof this area would be great.

Thanks for the time guys, cheers!

 

Rust is oxidation, which occurs when metal comes in contact with oxygen, so air, which is pretty much every where
Water and salts(minerals) speeds up this oxidation
Oxidation is literally "burning", a fire is oxidation, just happens alot faster, lol, but rust IS the metal "burning up" it vaporizes, disappears, same as the wood in a fire

So thats what it is, so how to prevent it?
Thats what paint is for, to prevent the air from touching the metal in the first place

But once the rust starts its hard to stop, just painting over it can slow it down, but the paint won't stick well to rusted metal, looks better though, lol

There are chemicals that can help, Naval Jelly is a good product, its a jelly so it can stick to vertical surfaces
Use a wire brush to get as much surface rust off as you can, vacuum it up
To apply the jelly you brush it on, WEARING GLOVES!!, it will eat paint, so be careful, then work it in, wait 20min and wipe it off, then rinse area off with water or use a wet cloth to clean the area
Repeat as you see fit
The chemical stops the rusting and changes it to an inert compound
Then after area is dry, paint it with PRIMER, primer sticks to metal, paint does not, but primer is not a good sealer, so after primer dries then paint it to seal out the air

Outside of cutting out the rusted area thats about the best you can do.

Looks like you are missing the threshold plate which would cover that gap in floor mat, also what those holes are for, screws that hold the plate down

 

Thanks a bun for the input.

Using some rust converting primer and then painted over it. Hopefully that will slow the spread a bit. I'll probably end up going to the scrap yard to try and find that missing trim piece. I've more or less concluded that whoever owned this thing before I did was a moron, because they also took a pair of tin-snips or some similar tool to one of the interior panels for no reason that I can find, so I might end up replacing that piece too.