Recently bought a 2005 F250.. didn't see any rust until now!

At the bottom of every door, water seems to get stuck there between the rubber and the chassis.

How do I fix this?

Sand it down, brake cleaner, rust converter, anti-rust paint, rubberized paint, then spray/flood anti-rust liquid in the doors periodically?

 

Welcome to the forum!
What you will need to do is address the rust first. Sand it all off using 80 grit sandpaper. A Roloc will work nice too, if you have an angle grinder. Once all of the rust is off, you will need to spray a DTM (Direct To Metal) primer followed by an epoxy primer, sand with 180g and then 320 grit, then base and clear. You will not have to spray base on the entire panel but will need to reclear the entire panel as clear coat cannot be properly blended (i.e. if the rust were on the lower part of the door, you would need to rebase the entire door, only the repaired area, but you will need to scuff the entire door with 320 grit and reclear the entire panel). Good luck with it!

 

Thanks for the advice!

I forgot to mention.. rust is limited to inside of the door.

 

No problem, glad to help out a fellow Ford trucker!
That actually makes things easier, and cheaper. You will not have to worry about shooting as much material, and the convolutions give you a greal place to lay tape lines, so you will not have to spray the entire inner door. Just remember to remove the door panel first, don't just tape it off.

 

What was truck used for previously and operated in what environment?

 

It's mostly been used as a daily driver by the previous owner.

Meaning, driven in Ontario where they put salt on the roads.
(Snow, lots of snow)

The problem is that little rubber thing at the bottom of the door that prevented water, dirt, salt from leaving the area..

 

What mileage?

 

60 000 miles

 

once you get it fixed.spray a bunch of fluid film down inside to stop the rust from the inside.

 

Why Fluid film?

Why not oil? anti-rust stuff?

 

Have you run past the rust through warranty?

Ford will fix it for free.

 

Bad News: The warranty is long gone..

Good News: 1/4 of the doors are done


Here's a better picture:




What do you guys think about putting phosphoric acid in the door?
Phosphoric acid - Wikipedia, the free encyclopedia

Then a few days later, Fluid Film or the equivalent...

 

How long is the rust warranty?

 

I see you have the tube steps. On my '99' I put that style of step on the truck and had the same thing happen after the 3rd year. When I got the '05' and this '08' I went with the Ford Full step for the extra protection from the snow/salt hitting that part of the door and have not have the rust problem since.

It looks like you'll have that problem solved with a little more work. Good job. Get the seam good that rust hides down in there.

 

Not a fan. Just do it the old fashioned way, some sandpaper and a little elbow grease. Acids can penetrate the flange seam and cause a loss of seam sealer material or even the adhesive that bonds the outer skin to the inner door shell.