How should I deal with this rust on the underside of my older F-150

[Gus_Mahn]

To me that looks like a perfect candidate for coating with boiled linseed oil. Just knock the loose stuff off and spray. Slow drying and low viscosity, BLO will creep into the rust and scabs. It may drip for a few days and can stain your driveway. It’s old school, but it’s a great way to stop rust. I spray my truck every other year. At ten years old in the rust belt, it still looks great underneath.

 

[Snagglefoot]

I would soak it with Krown or equivalent and touch it up every spring and fall.

 

[jsean]

If you plan on keeping it more than a couple of years, I’d highly recommend scraping the loose rust off, wash it, do the 3 step POR15 approach. On the insides of the rails, generous application of fluid film.

My pathfinder had similar rust issues when I bought it 4 years ago - I did what I described above. All I do now is an annual FF overspray in areas where the por15 is starting to come off - but mostly to other exposed areas, fasteners and inside the rails.

 

[dlundblad]

Try Amsoil MP HP spray.

 

[Trav]

Those are bed supports. The main frame is solid and in good condition.

Those are readily available and not too difficult to replace. Find a indy that can pop the bed and replace them, the one on the right side of the picture has perforation.
Google "06 F-150 bed support repair pieces" there are many suppliers.

 

[Donald]

After you have replaced what Trav suggests you need to treat everything you can see and what you cannot see with a CREEPING rust preventative spray like Krown or Carwell or Fluid Film or NH Coatings, etc. You need a long spray wand to get into channels.

Those products will soak through the rust and stop it. You don't need to remove any rust. Just mud or dirt.

But to keep the rust at bay the areas need to be treated yearly. At least those in places where water off the road will wask off the rust preventative spray.

Avoid high pressure under carriage washes. (I use it just before a re-treat of the rust preventative spray). But not after that.

NH Coatings has a few products. One very thick one you can brush on that can be used in areas susceptible to a lot of road spray.

 

[mattd]

There’s no stopping that. I’d try to find a different bed if you plan on keeping it. It wilo
Be the cheapest option in the long run. The bed rails are already junk, there is a decent size hole on the middle right of the photo. The bed floor won’t be far behind.

 

[Fitz98]

For any intact areas that can be reached, this is the only product I have found that is holding up on several rust repair projects I have done.
This Eastwood Rust Encapsulator Platinum seems to do a great job and hold up well. I have used the rust reformer and the Ospho, neither seems to work for any period of time. This is the product I use when the other repairs I have done in the past with Ospho have failed.
I have samples that have been left outside on steel for over 3 years and still not rusting.
My understanding this does not "convert" rust like other products claim, but rather encapsulates it to starve it from oxygen, which is what feeds rust. Here is a link to the product.
Eastwood Rust Encapsulator Platinum

A word of caution is to only buy what you can use, even the smallest amount left in the rim of the can when you close it back up will literally weld the lid shut and you cannot get it off...it is that strong when it cures. Also any air space in the storage container and it will turn hard over time.

As others have said rust inside would also need to be treated, I don't think this would help with that, but will do a great job preventing rust progression on the surfaces where it is applied.

Trav's suggestion makes the most sense if you are in a position to do that. Rust always wins in my opinion, especially at advanced progression.

 

[alcyon]

Rust converter twice, then paint over with rattle can , and then FF.

 

[Lubener]

There’s no stopping that. I’d try to find a different bed if you plan on keeping it. It wilo
Be the cheapest option in the long run. The bed rails are already junk, there is a decent size hole on the middle right of the photo. The bed floor won’t be far behind.

He's got more time with it. I would wait till it got worse before replacing the bed. . Who knows, he may replace the truck before that.

 

[mattd]

He's got more time with it. I would wait till it got worse before replacing the bed. . Who knows, he may replace the truck before that.

It’s thinner than it looks. Just speaking from experience from working in fords in the northeast almost my entire career.

 

[wlk]

Spray it with Ospho, let it dry, rinse with water and let that dry. Then coat it with Woolwax, Fluid Films or lanolin based coating.

 

[Bluestream]

He's got more time with it. I would wait till it got worse before replacing the bed. . Who knows, he may replace the truck before that.

Exactly, that is not major rust by northern standards, and we are not looking to do a full restoration. Scrap off the loose rust and oil it. Move on

 

[camrydriver111]

I would not use any hard paint or coating. It is likely it will continue rusting underneath the coating. I would also oil spray.

 

[JTK]

Based on what I can see in the pics, those bed supports are pretty far gone to put too much effort into saving. I'd be more concerned about the box frame, brake lines, rocker panels, cab corners, etc.

I like @Trav 's advice in terms of a repair (as always), but a good used box might be cheaper/easier if it comes down to where you need to do something.

 

[belbers9715]

Honestly, all the advice already given is solid advice. What I would do is a rust converter spray followed by Amsoil MP HD spray. Simple and cost effective. MP HD is essentially Cosmoline. Will stay put a long time and delay the rust significantly.

 

[Rand]

It’s really not a lot of work. We all know FF washes away from exposed surfaces. Rust encapsulation has been proven to stop rust. Given the severity of the exposed surface I’d want something tougher than FF on there to limit exposure.

Given that it’s blind on the inside, and my long term experience indicates that FF holds up well in protected locations, I agree that’s a good option once the exposed surfaces are dealt with.

Let me clarify:
I feel that it IS alot of work.. because those are pretty far gone.. the one middle section looks like it is almost JUST rust..
If they were in better shape your idea is also a good one.

Do you feel any of those bed supports would stand up to a small rock hammer.. maybe in places.

Hose down with FF, krown etc and know they need replaced or bed replaced... in a few years.

 

[JHZR2]

Let me clarify:
I feel that it IS alot of work.. because those are pretty far gone.. the one middle section looks like it is almost JUST rust..
If they were in better shape your idea is also a good one.

Do you feel any of those bed supports would stand up to a small rock hammer.. maybe in places.

Hose down with FF, krown etc and know they need replaced or bed replaced... in a few years.

I’ll bet they will stand up to reasonable force. Smashing it with a 2# mallet, maybe not. But there will still be structure.

 

[Bear]

I have a similar issue with my F150. Due to surgery and some other health issues I haven't kept up "rust proofing" it the past two years. When I finally got underneath a few weeks ago to install the nerf bars I was met with a rusty scene. I'm thinking of going to Zeibart and having them do the job. I'm not in great condition to do it myself at this point. Nine year old truck, no issues other than this. Worth the cost?
Oh, and the Rustoleum rust converter is what I've used in the past to spray and brush on.

 

[vavavroom]

Needs surgery.