Underneath rocker panel rust repair

So, I had installed years ago the basic running boards attached to the rocker panel underneath. Lately both rear mountig 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?

 

If that's the frame, it's structural. And welding would be the right way to proceed w/ repair

 

Yikes! What part of the country do you live? I'm guessing somewhere that uses salt on the roads.

 

Cut it out and weld in new patches. Seam sealer is a hack and not a fix

 

Technically body rust on a “body-on-frame” vehicle is not structural. However, the body structure does play a role in distributing crash forces, it’s crashworthiness might be somewhat diminished. Particularly for side impacts, in your case. That’s not to say a perfectly fresh 4runner body is great at handling crash forces (unibodies are generally much better at absorbing crashes in a safer manner).

In your case, I’d be worried about the frame as well. 4runner bodies are actually pretty good at resisting rust. So if yours is that bad, the frame might be worse. I think it would be worth taking a good look at the frame, especially the body mounts and the frame rails around them, suspension mounting points, and the crossmembers.

 

1. I'm in Boston, have had this truck for 7 years. Previous owner was in VT for 3 years.

2. The frame is solid, no rust. No other structural rust. The entire truck was treated repeatedly with Fluidfilm or equivalent.

3. The rust here is in the rocker panel. The drain holes must have plugged allowing water to do its thing. The mounting points for the running boards, where you see the bolt holes, are mostly solid as they are reiforced areas; mostly means only 2 out of 6 mounts are flexing.

If anyone can recommend a shop in MA or vicinity for the work, go ahead.

 

Good to know the frame was protected.

I’m curious about the rocker panels though…if you get another chance to look down there, do you see any evidence the insides of the rockers were previously sprayed with fluid film? Can you feel any fluid-film like coating in there, or see if the drains are plugged up?

The reason Im asking is that I’m thinking of spraying the insides of my rocker panels. But I’ve hesitated because I go through muddy water on occasion (including sinking it up past the rocker panels once), and I was worried the grit attracted to fluid film will plug up those little drains.

Oddly enough, after pulling the body plugs and checking the insides of mine recently, it doesn’t look like it was holding any silt and the drains were open. I want to keep it that way and avoid anything that might change that.

 

No Fluidfilm inside rickers - that's why they failed, partially. My drains were definitely plugged. I just never thought about checking when I purchased the truck.

You can spray with Fluidfilm but you'll need to periodically stick a knife through the drain holes to clear them. Water won't stick to Fluidfilm, it'll just roll off and stay inside - if plugged. Give it a HEAVY dose of Fluidfilm, reapply every 3 years.

 

so it's roughly 10 years old? I'm in Canada, Ontario, I think I will be racing to my local fluid film guy. Where abouts are the drain hole located? Pretty visible?

 

10 years old and 62K miles.

Drain holes are slits, you can spot some in my last pic, near the bottom, look like bumps. A regular kitchen knife, 1/2-inch wide works easily. Just stick it in there and move it around a bit.

 

Thanks!