Yesterday I took off the left front outer fender of my Amazon, and observed the same phenomenon as on the right side.

While the mounting surface on the wing itself was in relatively good condition, the box section on the inner front fender (which holds the fender's mounting screws) crumbled completely even without touching it.

Does anybody have any idea while this box section seems to rust from the inside out? It has a drain hole in the front, so any water in there should run out of it. Is it because the inside never got a decent rust protection coat of whatever they used back then?

I noticed in the replacement panels that the inside of the box section seems to be unprotected, but my general impression of replacement panels is that they don't hold the quality that Volvo's original panelwork had.

Not surprised, just curious...

I do believe that the drains get plugged with debris easily. Also, zealous undercoating appliers often plug them up.

A vent at the top could be a good idea if coupled with regular clearing of the lower drain and (at least) a decent paint job on the panel. It seems that once moisture gets in it evaporates and condenses on the panels causing them to rust faster, especially if the pait was not very good in the first place.

Good painting after a repair ought to do the trick without having to punch more bungs in the chassis.

Mike!

Well, the drain hole in the front is into the engine compartment I believe. And, the original paint had been painted over, effectively sealing the bolts off. Maybe the water got in between the mounting surfaces of the outer and inner fenders. Or maybe it got in there before the repaint and did the damage before. I'm not sure about the drain hole being there in the original box sections though, will check this weekend.

Joris;

I'm having trouble visualizing exactly where you are talking about. I have rust issues just in front of the front-most mounting flange also but they are holes in the frame extension (I believe from debris build-up trapping moisture). A close look at my "free" 122s showed rather extensive rust "repair" (using flat-iron strap... shudder) at all the inner fender mounting flanges. From the radiator support area all the way to the firewall. The fenders (wings) appear original and not crunched so I suspect iron worm.

My further suspicion is that the area of the mounting flange was never treated very well with either paint or rust-proofing so it was prone to water "wicking" in and rust doing it's thing.

Mike!

I think the water gets in through the bolt holes and doesn't drain very
effectively. Maybe the drain hole is located where dirt gets thrown into it.

I believe if it were mine I would, as a bare minimum, do whatever I could to
clean the interior of the section well, then slosh some good rust resistant
paint in there (maybe POR-15?). I kind of wonder if some vent holes into the
engine compartment might not be a good idea, maybe one near the front and one
near the back. I think I remember seeing a rubber grommet somewhere along
there. Also some sealant around the fender attaching bolts would
probably be good. On Li'l Red, the 67 122 I had in Panama, I ended up putting
longer bolts all the way through the box section because the top was rusted
badly.
--
George Downs, Bartlesville, Oklahoma, Central US