Re: Crack in the bottom end (skeg) of 1976 Johnson 40hp
If it were mine, I would drill the ends of the cracks so they do not go any further, use a low temp aluminum rod like the kind designed for a propane or oxy/acytlene torch( practice on some scrap before you attempt this) and finish it off with loc-tite anerobic sealer to make shure everything is sealed. To make sure it is sealed, I would use a shop vac and seal the hose to the inside of the cavity via a piece of plywood bolted to it-bolt the piece to the plywood, drill hole for vac hose, seal hose to wood and seal edges and ends with clay. Pull a vacuum on the inside and apply the loc-tite to the outside, it will creep into any pores and stay there. The vac is only necc to get the material pulled into the piece, it is not needed after that, let it dry thoroughly before re-assembly. Tig welding this can be done but may be fret with oil trying to come to the surface contaminating the weld. It might be possible to do this repair without welding at all and just do the loc-tite procedure described above. My 2 cents-Fwiw.