Rocker rust directly under front seatbelt tensioners

[repo]

I have no idea where the water is coming from to do this. You can see the sponge that is under the passenger seatbelt tensioner. From the inside is looks fine just dirty. It's not coming from the sunroof or the washer fluid hose. The rest of the rocker panel is fine.

Maybe from the front of the running board mount where the undercoating has cracked??

The driver side has it too but not rusted through yet, and it's further forward on the rocker panel.

Driver side:

 

[dogtail]

Rockers rot from the inside out on just about any vehicle, doesn't matter if you have a sunroof. Rockers hold water and condensation, there are drain holes in the pinch welds on the bottom of 3rd gen rockers, they clog, but doesn't matter regardless, you gotta spray some type of RP up in there, I use WD-40. Looks like your rocker pinch welds are taking a beating and not getting rust prevention. SEASONAL RUST PROOFING using WD-40 only

 

[Kanoe]

That's an unusual spot for it to go i think. They usually eat through nearer the rear wheels where the water and crap lies and the paint gets damaged.

I wonder if there was some sort of damage to that point in the past that took off the paint and primer and started the rust process... Maybe it too is a spot where stuff gets trapped inside but I have not seen one rust there.

Actually, looking at photo 1 and 2 it totally looks like that spot has been sandblasted. There is damage to the paint and primer beyond the rust hole. And that running board bracket has a ripped hole, did your 4runner sustain some damage in that area?

 

[MaineRunna]

Might be sunroof, but I think it's just a bad weld or bad seam sealing. That's a really unusual place for the rocker to rust out, it's usually at the ends.

 

[repo]

That's an unusual spot for it to go i think. They usually eat through nearer the rear wheels where the water and crap lies and the paint gets damaged.

I wonder if there was some sort of damage to that point in the past that took off the paint and primer and started the rust process... Maybe it too is a spot where stuff gets trapped inside but I have not seen one rust there.

Actually, looking at photo 1 and 2 it totally looks like that spot has been sandblasted. There is damage to the paint and primer beyond the rust hole. And that running board bracket has a ripped hole, did your 4runner sustain some damage in that area?

Not in the 13 years I've owned it but while I've been poking around I noticed the rear passenger door on that side doesnt have any Toyota stickers on it like the others do. And the only other body rust is around the driver side cargo area. The left cargo window has been replaced and on the underside below the left bumper there's places with a black coating/paint where white paint should be, and the pinch welds are all bent up.

 

[repo]

Might be sunroof, but I think it's just a bad weld or bad seam sealing. That's a really unusual place for the rocker to rust out, it's usually at the ends.

Do you know if there's supposed to be one of those little bent out drain holes in that area like the rest of the panel? Because I can't see the remains of one it's just rust.