I second the epoxy. I repaired a cast iron hot water radiator in my house with epoxy 19 years ago. It is still holding fine.

There are also products available to weld aluminum with a propane torch. I've made a number of aluminum saddles for my canoes with one of these products and the welds have never broken.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13