This is cross-posted from another site to get more opinions.

So, I had installed years ago the basic running boards attached to the rocker panel underneath. Lately both rear mounting points were flexing when stepping on the boards. Well, I removed them, got underneath and started poking with a screwdriver. I found quite a bit of rust, knocked it out and now I have holes to deal with.

I've sprayed the inside with some rust converter and plan on spraying it again with some cavity wax after the repairs. Will be replacing the boards with rock sliders, attached to the frame of course.

I don't believe this is structural damage, correct? Can I fix it with some seam sealer and pieces of mild steel? Or is welding required?

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Sorry to see that rust. I am in no way an expert, nor am I welder, but I would go all the way and cut that rust out and weld in some new pieces of metal. It would give me peace of mind knowing it was done right. Just my two cents.

Good luck!

man that is a lot of rust. how does it get that bad after only 10 years. I have a 2012 that's seen 12 years of canada winters and road salt and my rockers are fine, it has never been undercoated. was the vehicle ever in a salt water flood?

I don't think a repair of that magnitude will be cheap. I suspect that whole rocker panel needs to be replaced. it's probably rusting from both sides, inside and out. to try and save the rocker I would take it to a professional. that really sucks man...

I've had the truck for seven of its ten year life and never even been in water that deep. The drain holes were clogged and I never checked.

As this is UHS (ultra high strength) steel, shops are telling me that they will only replace it as officially required by Toyota. That's $7K per side or more, one quote.

Welding UHS seems to be a specialized and technical job. Finding a qualified person will be difficult.

The more I think of the welding difficulty, the more I lean towards the 3M structural adhesive and mild steel. I'd bet that's more than enough to keep me going.

Frankly, I can't believe that simply clogging these drain holes leads to total replacement of these parts at considerable cost. I'm sure a repair will return the strength to good enough, albeit not up to Toyota's standards.

the drain holes were clogged with mud or dirt? what was clogging them? that looks like some serious salt water damage after prolonged exposure. at $7K per side no way I'd put that money into a 2013 truck. If I had the $14K to spend I'd sell the 4runner as is and use the proceeds plus $14K to move onto another vehicle. I bet if you start poking around there with a screw driver you will poke holes all through that rocker. is there any good steel left?

There's no severe rust anywhere else underneath, except minor surface rust here and there. The drains were clogged with who knows what.

I have poked around and all seems good, certainly no punch through to the outer rocker. I really sprayed the hell out of all the inside with Corroseal, a rust converter I've been using for years, to the point where it was dripping out of all the drain holes.

I believe the only way to go now is with 3M. I need to find a 4x4 shop where they're not afraid to think outside the box.

Can someone help point out where these drain holes are? Will add to my list of routine maintenance/check. Perhaps blast Woolwax through.


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Look at my third pic. From the left side, see that big bump on the bottom of the panel? Stick a flat blade up there to clear debris; a kitchen knife works for me.

Assuming you haven't blasted the interios with anything, I would first use a rust converter to tackle any probable rust in there. Do it liberally. Then wax the interior, clear the drains afterwards, obviously.