There was a rusty spot.
I poked it.
It crumbled.
I opened up the hole to get to good metal, and to access the inside. The funny thing is that the rest of the long is solid. If it's battery acid related I would expect a hole into the top, and then a hole out the bottom. No hole in the top, bottom or inside, but a hole in the outside. It's made of two layers, so my current theory is that water/battery acid seeped down between the two layers and rusted them simultaneously.
So now I had a hole that had to be fixed. First I cleaned out the inside and put por-15 on everything I could reach in there. Then I made a cardboard template slightly larger than the hole. I decided that putting the patch on the outside wouldn't do because I could only weld to the outer layer of longituinal. The template was too big to go inside in one piece, so I cut it in half. Then I used the template to cut two peices of 10 ga. steel, which I bent to fit the shape of the long. I tack welded a bolt to each piece so I could pull the patches against the inside while I tacked them in place.
After that it was a simple welding job.
Andy
It's a joke for cryin out loud! 