I have a '05 FX4 and under the cab there is some surface rust around where the cab braces are attached to the wall of the cab. I live in the rust belt and have been noticing the rust showing up for the last couple of years, so far I've been spending a weekend every spring cleaning up the rust as best as I can and where I can get to it and then spraying the bare metal and light surface rust I can't get to with rust killer primer followed by paint. I've got ahold on most of it but there is still some there. I know it's a loosing battle where I live, so my question is if I just leave it do you guys think it will completely rust through fairly quick or will it stay on the surface for awhile? My wifes '07 has alot of it in the same spots, but I haven't done anything to the truck since we bought it last year. Her truck will be the one to get traded first so I'm not really worried about it, but I plan on keeping this truck for another 5yrs and don't want to end up with a truck with a perfect body on the outside and holes rusted through underneath.

 

Actually I was going to start a thread regarding this. I noticed on mine that on the OUTSIDE of the body. Rear cab corneres on the bottom, paint peeling and everything. Not pleased. Will have to sand and repaint. Also on the bottom where my running boards would attach, the whole edge is coated with rust. I live in MN, so it is to be expected, but I was hoping that I could keep it nice for a while longer yet.

 

I hear ya, I had the rust alond the edge where the running boards attach also, I sanded the heck out of it last spring and coated it with paint and so far so good. Ford got rid of the rust problems with the wheelwells that the pre '97 trucks had, but now they got a new set of problems to sort out. I've looked at pre '97 trucks and the underside of the cabs are always pretty clean, but the cab is set up different underneath. What is bad for me is that I don't drive my truck alot and right now I only have 50,000 miles after 4.5 yrs and will probably only be around the 100k mark at 10yrs and might have a truck that has alot of drivetrain life left but might be rusted out underneath.

 

i think of rust like cancer. get it out of there! it is going to kill your body. I too deal with this every year. sanding and painting. cans of rustolium. 2 years ago an old man from down the street gave me some advice,he told me to wash the undercarraige then spray the belly with mineral oil before the first snow. i have seen a considerable decrease in surface rust the last 2 springs since i tried it(almost nothing). all of my vehicles have benifited from this.

 

I heard that oil trick too, I am starting that this spring on my new ford.

 

I had rust in the corners of both sides at the rear of my cab. I cut out a bigger area, and sprayed the inside with Rustoleum rust inhibitor and let it sit for 24 hours, per the can. After that, I took expanding foam from the hardware store and sprayed it inside to fill up the void and let that cure. Then I cut away the foam and sanded it so I had a uniform surface with the surrounding area, then took used a Bondo fiberglass kit to make a patch across the surface, followed up with Bondo Glass putty, and finally a smoothing coat of regular ol' Bondo, and then sprayed primer over the area. Because I didn't want to hassle with matching paint, I opted to scuff the paint along the entire lower portion of my truck and I used spray-on bedliner along the bottom edge of the truck like you see some people do with Rhino or Turbo liners. Gave it a matte textured look, and to everyone else, it was just an aesthetic choice. Been about 9 months so far, and I haven't seen any rust bleeding through the paint.

 

I am building what Ford didn’t. A Crewcab long bed 4x4. Here is some of my

 

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