Is this just a little rust or leading to bigger issue later?

[MisterCruiser]

Happened to be removing the rear interior taillight access plastic cover on the drivers side of my swb colorado and found this little rust, the outside wheel arch is fine. Is this just a little bit of rust that we see or is there likely to be more that I can't see at the bottom of the little pocket area.

I've painted the entire underneath before twice and its in good overall condition rust wise I think, and just passed the Doe / Mot without any issues or mention of rust. I'm just concerned that I found this as I forgot about this area. Whats the best way to patch this or would you patch it, best just cleaning it up and treating it so it doesn't get worse and not worry about the little hole there as its not major structural or anything. I'm guessing its not worth fixing via actually welding in a little patch of metal, or would you?

 

[StarCruiser]

In my limited experience, rust is usually what you can see pretty much doubled. So not a whole lot but a hole nonetheless. And in a swine of a position too. Further investigation required. Then cut out and replace anything affected, which could be a simple patch if it’s not on show but my guess is you’ll be needing to clean out all around the wheel arches and under any arch extensions (removal and refitting is best for this) and assess whether there’s any more to contend with.

Good luck with it.

 

[Jack VZJ90]

Just weld it .....

 

[MarkW]

Check in the very bottom while you have it open and see if its got wet mud in there, mine did from the previous owners. There are a couple of bungs in the bottom so you can remove these and jet wash out the crud.

Also have a look around the read body mounts inside the car, Toyota thought itd be a good idea to fill the space with foam which gets damp and causes rust

 

[Jack VZJ90]

They put the foam in for noise.
If you weld it, first get the foam out !!