This is about home appliances, but it could help fixing your bike too.
Last week, my wife called me because our old Maytag washer was leaking. When I open the front panel, I could see a dent in the tub and rust marks (The dent was made at the factory, and later I found that the enamel got chipped inside the tub). Took a mirror and was able to locate a pin hole. I got a piece of sand paper, cleaned the area and poke the hole with a screw driver. The hole became bigger and bigger to the point that I decided to take the whole thing apart. Here is what I found looking from the inside of the tub....


Maybe, we should buy a new washer..... NO! This is not a question of money, but a question of quality. Few weeks ago, I was watching this excellent show and last week I was listening to a radio program where the appliance repair man was advising people to keep all their old appliances for as long as they could.....
Why are we riding 30 years old bike? for the same reason.

JB Weld would definitively don't work for this.
The solution was to use what I always carry in my bike's tool kit :Quick aluminum epoxy

This product is really easy to use: you Break off a piece, knead it and apply. It dries in 15 minutes. It works well for anything where it's no torsion, friction or stress.
The tub of the washer fits this description.

When the quick aluminum was cured, I applied a coat of Marine JB weld over to be sure that the tub would be 100% leak free.

Note:
If you are a handy man, you should take your washer apart for a good cleanup. I was amazed to find a lot of areas covered by mold. Any part like the tub cover which is only splashed by water will over time become moldy. The problem is that unless you take it apart, you cannot see the dirt.

This quick aluminum is not new. Years ago, the chain broke on my Honda CB 750. The chain rolled around the front sprocket and exploded the bottom of the engine block.
I got a motel room, patched the hole in the block with the quick aluminum, let it cure over night and the repair lasted until I sold the bike 5 years later.
The difference between the quick aluminum and JB Weld is the consistency of the product:
JB Weld is quite runny when the quick aluminum is more like the glaze used to repair windows. You can patch a hole without having a back support.
Quick aluminum is cheap and everybody should carry it in their tool box. I was reading on the Avid Riders forum that people even fixed a broken clutch lever with it. This is only a temporary repair, but if it gets you back on the road until you can buy a new one, it's worth the $10.