Any experts here on rust pitting repair and repaint?

[Kingcreek]

I’m throwing enough money at the Jeep right now that anything more pro is out of the question.
I’m doing this myself one way or the other.
My 4 door wrangler has the factory rubicon rock rails. I noticed some rust at the plastic end caps and decided to remove them and clean them up and repaint. I found a lot more rust and some pitting under the textured bed liner type of finish. I have used wire cup brush, wire wheels, flap disc, and emery cloth. I am down to bare metal and primed with good rust blocking primer but I have pitting i need to fill as well as voids where the finish was a lot thicker than others when I cut through it especially around the pillar spacers.
I plan to use a textured paint or spray on bed liner for final but I want to get them looking good when finished.
One side was pretty minor but the other side looked like crappier welds on the pillars and I’m almost sure some welding scale or flux was painted over, hence the thicker paint.
I’m considering j b weld for filler and then sanding it smooth. Removing all the textured finish would be a monumental task.
I have no body rust. The pinch seams look like new. I want to keep the rails. They do a great job of protecting from the parking lot door dingers. I’ve never been up against trees or rocks.
Thanks

[dogmush]

Bondo is what one normally uses for this.  How big are the sections?

[Kingcreek]

The worst areas are about what I could cover with 3 fingers. Maybe 3x4”.
Non of the rust is through and none of the pits are terribly deep. Metal tubing looks to be 1/8” thickness.

[JTHunter]

King - there are times that I am cutting long pieces of firewood off of my tailgate with a chainsaw.  As a result, I have nicked the top of the 'gate twice.  I took a small hammer and screwdriver to hammer the rough edges back into the cut, making a slight pit.  I followed with a small rattail file to smooth off the edges, followed by an alcohol wipe to clean it.  Then I mixed a small amount of JB Weld and pushed it into the hole.  I used "duct tape" on the side to keep the JB in the hole and it has worked fine.
The advantage of Bondo is (IIRC) that it isn't a 2-part that you have to mix.  It's just that it isn't as structurally strong as the JB but it will cover a larger area more easily than JB.
Good luck !

[Kingcreek]

I picked up some JB weld sand-able (metal/concrete) 2 part epoxy. Going to give it a try tomorrow. If I can fill and blend with a palm sander hopefully I can get it looking good when finished.
I did find a little rust after all on the pinch seams at the rear corners. They will be covered by the rock rails when remounted but I’ll clean that up and shoot some rust reformer on it also. It won’t be visible so I don’t have to match body color.

[Bogie]

Yeah, Bondo is a two-part, and a pain... If you can fill in with weld, and then grind/sand, that would be optimal. Otherwise, JB is a good choice.

[French G.]

If you do anymore I would skip the down to bare metal and use a conversion coating such as Extend. Really does good to prevent rerusting under the paint or filler.

[BobR]

Yeah, Bondo is a two-part, and a pain... If you can fill in with weld, and then grind/sand, that would be optimal. Otherwise, JB is a good choice.

Lead, that's the ticket. Harder to get a better seal than a proper lead fill. Back when the Imperial Palace had a huge car collection in Vegas they would farm out restoration work to one of the local prisons and one of the things they took pride in was being able to lay in lead for repairs. If not wanting to do lead Permatex makes a good one part filler good for small areas. Evercoat makes a lightweight filler that stays creamy longer which can give you more time to work.

bob

[Tuco]

It doesn't offer any fill charateristics, and needs to be painted, but the first thing that came to mind when Kingcreek described his rusty member was POR-15.

[Kingcreek]

Lead would be great if I was removing all of the rubberized/plastic finish but if I applied any heat it would blister or lift. I’m trying to control the rust as well as fill the pitting and build up and blend the areas where I had to remove the thick finish.
I’m not familiar with POR-15 but I did use a “rust reformer” that is supposed to make a rusted surface ready to paint. Also used a good rustoleum primer.
I would like to be able to get further than 5-6” inside the ends of the tubes but I’ll have to settle for what I got.
There are plastic end plugs/caps and they cleaned up good. They fit snug enough to be almost watertight. I’m tempted to use some silicone sealer but if the tool on any moisture it would be in there forever. There no weep holes originally.

[Kingcreek]

Going pretty well. My JB was hard right out of the new package so I had to make the 14 mile round trip. Got a pro size quick weld JB which is going to work out better anyway. It sets in 6 minutes and sands really easy in 2 hours, 4 to full cure.
I have a final fill to do on some spots I didn’t lay enough and a disposable foam brush actually works pretty good.
The oscillating multi tool with triangle sanding attachment seems made for this.
I wanted to finish it today but I’ll let it cure good overnight and spray the bed liner tomorrow after a final sand of the built up areas.
Then I get to remount the rails, 50 pounds each maybe?
Gawd but I do love an air conditioned shop on a 90 degree steamy humid day.

[zxcvbob]

If it's really shallow, there's something called "spot putty" that comes in a tube.  Dries hard, sticks tight, can be sanded.  But you can only build it up in thin layers if you want it to dry.  It's ideal for pitting if you've killed the rust.  Once you've got it pretty good, use a sandable automotive primer (usually gray), they are somewhat gap-filling.

[JTHunter]

Yeah, Bondo is a two-part, and a pain... If you can fill in with weld, and then grind/sand, that would be optimal. Otherwise, JB is a good choice.

Thanks for the correction.  I've never used it but thought it was like "mastic" for sealing sheet metal duct joints & seams and just had to be "troweled" on the surface. 

[Kingcreek]

Got it all done and back together looking pretty good. A couple minor spots could have used a little more filler but I can live with it.
The rattle can bedliner worked great. I used rust reformer on the bare metal, followed by grey primer.
The JB quick weld worked good for filling and blending once I got the knack of how much I could mix and apply before it started setting (6 minutes).
I found an old gun style handle/trigger that attaches to spray cans. I hadn’t used it in years because the spray tops changed. Oddly, the bedliner (new product) had the old style top with the small button that fit the old spray tool. Since it was a big and heavy can, that helped a lot.
I’ve got a little work to do under the Jeep to wire brush some surface rust on the frame and suspension and I’ll hit it with black rattle can rust reformer. I’ll also treat it all with fluid film before winter. I did it 2 years ago and it really seemed to help. I’ll pull the end caps and shoot the rock rails inside also.