Rocker panel minor rust repair

[MrPaco]

I have a little bit of rust at the bottom of the rocker panels and want to address it before it becomes an issue. I already tried it once, but the rust came back. I have a new idea I'd like to try, but want to get some opinions from others with experience on rust and body work first.

The rust is at the very bottom of the panels, I previously stripped off most of it, and some of the paint around but since the metal is thin in this area I was afraid of ending up with holes if I stripped too much. I stripped as much as I felt comfortable, then I hit it with loctite rust neutralizer, then primed and painted. It took about 2 months for the rust to show up again through the paint, so it didn't work.

I'm thinking about doing something different this time: Stripping the paint down to the metal on a 1" strip down the whole length of the panel, making a clean cut. Then leave it uncovered so that it rusts a little bit and and when it does, hit it with rustoleum rust converter so that it creates that black surface that becomes rust proof. Then cover that with rustoleum undercoating, or maybe spray on bedliner.
The rocker panel would end up with a black 1" strip at the bottom (mine are silver), which I think will look fine, and the new surface would be more chip and rust resistant. That's the theory anyway, can you tell me if this could work or if it's a stupid idea?

Thanks

Some of the rust spots after they came back (the last one is what it looks like after stripping most of the rust off):

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[StarquestMan]

Im sure someone else with more experience with rust than me will comment but i would be weary about that rust converter stuff being very permanent especially if left untreated with a sealer primer of some sort. do you have a small mirror like a small mechanics mirror? i was looking at my truck and there is a small rubber plug at the very bottom rear of the cab on each side. try taking it off and take a look inside if you can. look for any signs of rust or moisture. hopefully everything is all good there but if not that may indicate that it is rusting from the inside out. i would use a good self etching (also called metal etching) primer followed by a sealer primer and then paint with an optional undercoating to prevent chips. I would only do this though after checking to be sure it isn't rusting from the inside or else this will only hold moisture in and speed up the rust if anything. my dad had an 87' 4 runner that had some bubbly rust under the paint that continued to get worse and my theory was that the paint helped hold in the moisture coming from inside the pinch weld along the rear fender.

[geezer101]

I second that. I tried using a spray on rust sealer called Penetrol which was supposed to soak into the rust and then dry as a clear coating but it didn't work. The doors I treated didn't last 2 years...

[85Ram50]

It looks like the rust converted to iron oxide to me. That is the black color. And it looks like he's cleaned it up to get rid of the loose rust. My experience is that if it is dry, degreased and he seals it that spot won't rust again.
If you get rust in the area again it means you left active rust behind.

[tortron]

This will be caused by rust coming through from the inside. In this case between where the inner and outer sill join.

Because it's already started (and the majority of it is not seen) it will be difficult to stop, but you can buy some time. Flood the sill with your rust treatment (phosphoric acid, that's what turns it black) and then flood the sill with cavity wax. Do this till it drips out all over your garage floor (get the wax hot so if flows better, a nice summer day is perfect along with keeping the can in hot water) it will wick into any panel joins and seal it from moisture and air.

[MrPaco]

It looks like the rust converted to iron oxide to me. That is the black color. And it looks like he's cleaned it up to get rid of the loose rust. My experience is that if it is dry, degreased and he seals it that spot won't rust again.
If you get rust in the area again it means you left active rust behind.

What would you use to seal it? just primer/paint?
I thought that's what I did last time, but you're probably right and there was still some active rust left. What was the name of product you used on the bed of your truck to neutralize? The product I used (loctite neutralizer) said that if painted over it must be with oil based primer/paint, but I'm not sure if what I used was oil based, so that could be the issue. The paint I used was this https://www.automotivetouchup.com and I couldn't find any info on the product or the website about it being oil or water based, I even contacted the company but no response.

[MrPaco]

This will be caused by rust coming through from the inside. In this case between where the inner and outer sill join.

Because it's already started (and the majority of it is not seen) it will be difficult to stop, but you can buy some time. Flood the sill with your rust treatment (phosphoric acid, that's what turns it black) and then flood the sill with cavity wax. Do this till it drips out all over your garage floor (get the wax hot so if flows better, a nice summer day is perfect along with keeping the can in hot water) it will wick into any panel joins and seal it from moisture and air.

You're probably correct. To flood the sill, where does the rust treatment and then the wax go in? Is there a specific spot?

[tortron]

All roads lead to Rome
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Any of those holes will work

The wax does come in an aerosol can with a hose nozzle, otherwise if you have a compressor the gun that attaches to the cartridge is cheap enough and should have a long tube attachment

[85Ram50]

I used Skyco Ospho which is phosphoric acid. If you have access to the inside of the sill there are too oblong holes just behind the front of the seat on my gen one, covered with some sort of paper tape at the factory through which you could fill the rocker with treatments. Tortron's idea sounds good.

On treating rust if you are concerned with a permanent repair, you want to clean the area around the rust of paint so that there is at least a half inch of clean bare metal that has had no rust on it, then treat the rust and you have a good probability of getting it all. Once it is cleaned and treated (you can paint directly over the dried Ospho) just paint it as you normally would, a couple coats of good primer, then whatever you are going to put on top. Dupli Color brand is what I am using. For me I use flat black sandable primer. If you want bullet proof use an enamel primer, they also have that under their brand, then whatever color and clear coat you are wanting to use.

I recently sanded and painted the roof of my Dakota, it had a bunch of bondo repairs and rust spots under the factory primer. It was made in Ohio so I figure it got hail damage while sitting in the yard and that was how they repaired it. My Dakota is 25 years old. None of the rust looked active.

[StarquestMan]

tortron and 85Ram50's posts reminded me about these plugs that i saw on my 2nd gen truck. they run along the bottom of the back side of the rockers and should give excellent access for adding the acid and cavity wax.
Access plugs.jpg
one thing that comes to mind about applying this cavity wax is that it may be a good idea to temporarily plug the weep holes along the bottom of the pinch weld to help the wax run the length of the rockers and then unplug them so that future moisture can drain properly so it doesn't fill up and rust above where the wax is? since there is rust holes that needs to be repaired and we are on the subject what do you guys think of body solder? i know eastwood sells it and i have often thought of using some for some of my projects and it seems like a very permanent way to repair rust or minor body damage that may be a good fit for rocker panels that take more moisture and abuse? that is very interesting BTW about your Dakota having bondo and rust under the factory primer 85Ram50.

[MrPaco]

I was able to take a look inside the rocker panels by removing one of the rubber plugs on the back side, shining a flashlight into the panel and looking in from the square holes on top where the scuff panels screws in. Thanks to starquestman and tortron for pointing out those openings.

The good news is that there is no rust in there, so I don't need to worry about threatening that area. Just need to figure out a lasting solution for the surface rust issue on the outside that keeps coming back. I think I'll treat it with the rust neutralizer again but hold off on painting for a while, until I know for sure if it worked.
I did find a lot of pine needles inside the rocker though, so I have to figure out how those are getting in (my guess is through the front, from the runoff drains of the air vent cowls next to the windshield wipers), and how to vacuum them out of there so they don't collect moisture.

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[tortron]

Water would normally drain from one of these two vents
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Oops can't see it but there's one in the a pillar where my finger is. It appears to be fully sealed so water/dust wouldn't normally get to the sill from here.