My truck had a plastic drop-in bedliner when I bought it and knowing they are nothing but a rust factory I promptly removed it. After removing the liner I found a decent amount of lighter rust with a couple of heavier spots with some pinholes. I cleaned it up and hit it with some rustoleum until I could take care of it properly. I ended up putting in a rubber mat to keep coolers and other gear from sliding around in the bed and normally took it out once a week to make sure the bed was dry underneath. Well, I got busy and stopped taking the mat out of bed and ended up with this.

I'm going to hit the rusted areas with a wire wheel until they're bright and shiny and then seal it up. Not sure what paint I'm going to use yet, I definitely want something rust inhibiting though.

How about a spray in liner like Line-X® http://www.linex.com/

or Rhino Linings® http://www.rhinolinings.com/

I'm actually thinking about spraying it with this http://www.monstaliner.com

You probably can't tell but my entire truck is roll-on bed lined with thinned Duplicolor.

 

Edited November 28, 20159 yr by The_Hammer

It looks interesting. They have everything for a DIY guy. I like that its tint able with colors like " jungle love" "don't yell at me",  and "blood bath". I wish I'd known about the Chassis Saver™ when I was redoing my boat trailer. I did some looking around and this stuff is real popular with the off road and down in the mud 4x4 sites. I didn't see one bad thing about it. Keep us up to date on this project.  

I like doing things myself, but also money is tight so I HAVE to do most things myself. I do all my own mechanic work, carpentry, plumbing, electrical, welding/fabricating, you name it. I've also learned how to do some automotive body work and painting, though I'm no professional, let lol. Most recently I've learned to read wiring schematics so I could diagnose and repair my electric guitar amp. It would have cost over $400 to ship it to a repair shop and have it fixed when all it needed was a new resistor.

I've got all kinds of stuff planned for this truck and will be taking pictures and writing articles as I go along to hopefully incourage and help others. I'm going to be converting to the HD factory steering, building a shackle reversal, building extended control arms, installing 3" lift coil springs, rebuilding my steering gear, recovering my headliner, making some black diamond plate inserts to replace the stupid skull and crossbones ones on my center caps, ect.

Well the current plan is to remove as much of the rust as I can with a wire wheel, weld up the holes, apply a couple coats of Rustoleum rust converter, and hit it with some Rustoleum primer. Once I have the funds available I'll spray on some bedliner. 

Take it from a guy that has dealt with a lot of rust issues. There is no product out there that will stop the rust once it looks like that. 

If it was mine I would cut out the Swiss cheese and weld in a flat plate, cheap and easy. Might not look the greatest but honestly who is going to notice or care once it's under coated. I've experimented a lot with undercoating over "fixed" rust spots just like you're planning and I can pretty much guarantee it'll bubble through in a year or two. Just hate to see you waste time and money. 

Have you tried sand blasting? It was another idea I was kicking around. 

I have and it works pretty good. It just seems like once it rusts through you can never get it to completely seal up. Water works its way under the paint and rusts from the inside out. 

I spent a lot of time fixing rust last fall and the few spots I cut corners are showing through. 

I wish I could get my hands on the stuff my old work place used on salt water disposal tanks. They would refurbish some ratty old steel tanks that were covered in sheets of rust that were over a foot long. They would knock all the loose rust off then spray it with a reddish/brown epoxy primer, wait a day, then paint it. There were tanks out in the field 5+ years later that were still rust free. 

There are some industrial grade paints that work wonders but the common man can't get it. They have 55 gallon drums of the good stuff at my work but I can't get my hands on any. I've tried some commercially available, expensive "rust killing" paints with ok results. 

Found this interesting study on some rust converters by the NCPTT which can be found here. Below is an excerpt.  

"The five chemicals chosen for this study are listed below. The chemicals were chosen to represent each of the major types of rust converters. The chemicals in each category were selected based on their popularity in the commercial market place. The goal of this study is to provide the end user be it home owner or museum conservator with the knowledge needed to make an informed decision when selecting a rust converter.

Rust-oleum® Rust Reformer® is a tannic acid based rust converting product. It also has an acrylic vinylidene chloride copolymer additive. Tannic acid acts as a chelating agent while the copolymer creates a protective coating. The product has a pH of 2.13, falling in the mid-range pH of this study’s converters. Rust Reformer® has a relatively thick consistency, and is blue-ish white in appearance.

OSPHO®, manufactured by the Skybryte Company, is a phosphoric acid based rust converting product balanced with dichromate and wetting agents. OSPHO® is by far the most acidic rust converter of those tested. The product’s pH is 0.08, and is a thin, translucent green liquid.

Corroseal® is a rust converting product based in gallic acid. This converter is composed of gallic acid, ethylene glycol and acetate. It is relatively acidic, both generally and in comparison to other tested converters, with a pH of 1.50. Corroseal® is creamy white and has a thick consistency

Intern Anna Muto applying rust converter to test samples.

RCx427 is a product of Enviro-Safe Services, Inc. that uses oxalic acid as the rust converting compound. Like Corroseal®, it also incorporates ethylene glycol in the chemical composition. Oxalic acid as an active ingredient—a compound that exhibits different physical properties after conversion. Instead of causing the iron oxide layer to darken, it instead turns a light gray. Of the tested rust converters, this product is the least acidic with a pH of 3.11. RCx427 has a thick consistency and is a blue-gray color.

The 10% Tannic Acid solution stands out from the other rust converters in that the solution is not commercially available but must be prepared. However, a survey of metal conservators done by conservation graduate student Rose Daly indicated that the “CCI Recipe” for tannic acid solution was used more often than commercially available rust converting products. As such, it was deemed important to include in the study. The preparation method outlined in the CCI Note “Tannic Acid Treatment” was followed (CCI Note, 1989). As directed, 2.75 mL of phosphoric acid was added to lower pH to 2.39, and fell into the mid-range of acidity in this study’s converters. The solution is thin and appears a translucent, orange-red color.

At the end of the accelerated weathering only the samples treated with Rust-oleum® Rust Reformer® showed no or only slight signs of any failure and no active corrosion. This research was completed in the summer of 2012, afterwards the results were presented at ICOM CC Metal 2013 in Edinburgh, Scotland. The results of the study were also published in the conference proceedings. Click here for pdf of paper."

I ended up going a different route. I wire wheeled the entire bed floor, paying special attention to the rust holes. I then painted it with Rustoleum rusty metal primer and will topcoat with Rustoleum satin black. I'm also cleaning up and painting the underside of the bed where the holes are to seal things up. For bed floor protection I'm putting in a rubber bed mat.

The plan is to occasionally remove the mat and hose out the bed, then after a few months wire wheel the paint off in a couple spots to see how it's holding up. Eventually I'm going to find a bed in one of the local salvage yards to cut some patch panels out of. 

For guy here that lives in salt in country and has two trucks that have plastic bed liners. I'm still to this day rust free in the bed. The only thing I do is pull the plastic liner out once a year and hose out the bed and allow to dry. Then reinstall the bed liner.

I've been running thru the road dept. defrost liquid they spray on the roads. Should I park over a sprinkle for awhile?

I've never run over that stuff till lately?

That's all I every do is either park over a sprinkler or get out the power washer...

Rust is metal cancer, and in my experience like mentioned above the only right way of dealing with it is cutting it out. Also keep planty of paint on metal to keep air and water off of it. Sandblasting has to be best for removing rust, wire wheel and sending just works it in to metal and you never get it all off. After send blasting you could whipe it down with some thiner. Make it out of stainless, I'm planning on making my own bad in a few years out of stainless just got to find time and some more money. 

@Mopar1973Man

Everyone I've ever seen with a drop in bedliner ended up with lots of rust. They always vibrated around and sanded the paint down to bare metal, then water would get trapped under it, and then it was rust heaven. 

@Dieselfuture

I'm going to eventually weld in some patch panels.

talk about parking under a sprinkler, We use one of these where I work to wash under semi trucks, its like a sprinkler on steroids. just hook it up to a pressure washer. It will probably even knock off some of that loose rust

I have got to make one of those! That would be perfect for washing the underside of my truck after going to the beach.