What to do about a rusty frame?

[Egon]

Power wash everything you can get to including the interiors of the frame. Get the rocker panels and wheel wells too. Then spray it with a rust inhibitor. ( tremclad ?? ) Finish off by spraying on an under coating. If you make your own undercoating it can be quite economical. ( roofing tar mixed with diesel to the point you can use siphon gun to spray it. ).

 

[KennyG]

If it were me, I'd paint it with rust encapsulater and then frame paint on all the exposed areas. See Eastwood products for examples. I'd do it all with brush on paint. It won't cost that much and it's only a couple of days work. You can paint it with paint as quickly as with oil.

 

[3Ts]

Ospho converts the rust (iron oxide) to iron phosphate. The rust does not cling to the base iron, the iron phosphate does. The iron phosphate is a better coating than iron oxide in that it adheres to the iron and slows down the rusting, but it is not a top coat. It should be considered more of a primer than anything else. It's better than not doing anything, but it is not permanent either.

Edit: My approach is to use Oshpo on lightly rusted steel, then a zinc paint, followed by a top coat of paint. But, this is for structural stuff out in the weather. I've never done an automotive finish job and what I do is definitely not an automotive finish. For heavily rusted steel, I sand blast it.

 

[MossRoad]

How about some pictures?

One man's surface rust is another man's catastrophe. Pictures should show others what you have.

 

[Deere Dude]

After looking at my rusty frame of my dooly for a few years I talked to a couple trusted body shop guys and a car restorer. They pointed me to OReillys for some rust restorer and some sort of rattle can spray that is very tough. Four years ago I had to get the box off so it was the perfect time to coat my frame, springs, breakets etc. They turned out very nice and still looks great. Sad to say I forgot the name of it, but was made for frames.

 

[amhicks21]

Buy 2 gallons of black fluid film or wool wax (same stuff, different name) for 100 bucks add a pro spray kit for 100 bucks off of Amazon. Spend 2-3 hours spraying, and the underside of that truck will look beautiful for years. Once a year or two, spend 30 minutes touching up any spots that may have been missed. I have 4 vehicles with an average age of 26 years old that i drive all year and since spraying them, there has been practically no new rust. Im not the type to swear by a product but this stuff is the way to go. I also work for a company that runs 7 salt trucks and around 20 plow trucks and we use it on a bunch of equipment.

 

[Jstpssng]

Fluid film won't stop existing rust. It simply creates a layer between the metal and whatever might get onto the frame. There are other products which are supposed to actually interact with the rust and neutralise it.

 

[jjeff]

I remember when I was stationed in California, had to get new tires, the tire shop informed me my frame was rusted, expecting to see perforations I laughed at them when they showed me nothing but some surface rust. I started to think they were trying to scam me and wanted to buy my truck super cheap. Nope they weren't, non snowbelt folks think a little surface rust is the end of the world in some cases.

 

[Topzide]

Check out Black Star MROChem: We Have Your Chemical Solutions!.
Can be brushed, rolled or garden sprayer applied. Environmentally friendly! Photo of truck frame of my 2014 3500 Ram. Doesn't need a top coat but you can if you want.

 

[amhicks21]

Fluid film won't stop existing rust. It simply creates a layer between the metal and whatever might get onto the frame. There are other products which are supposed to actually interact with the rust and neutralise it.

Rust is iron oxide. Just iron and oxygen. If oxygen cant reach the iron, no new rust is formed. The reason that people think rust spreads like a cancer is because rust creates porosity. That porosity allows further exposure to air, water, and salt. If you saturate that existing rust with an air and water tight barrier like fluid film, new rust can not form.