Does anyone here know about welding a lower unit? Basically, there's a
hairline crack at the bottom that allows oil to leak out, and I want it to
be sealed up with a weld (as I don't know any other compound that would do
the job).

The motor is an early 70's Mercury 4 cylinder. I'm not sure what its all
made of, but likely a more traditional material would be the case.

Again, I'm not looking for a strength weld, but rather a sealing weld.
Maybe a bead would do the job.

Can it be done? ( I heard they can weld props, so why not this ).

Also, if you do know anything else that may work, please let me know. I
have considered JB Weld, but haven't gotten around to try that as a sealer.

Cheers

Chris