Don't give up on it yet. External cracks are repairable. There's a process called "sewing" where overlapping threaded plugs are installed in the area of the crack, which seal up any leakage. The crack is stop-drilled at each end, and the drilled hole is threaded with a tapered tap. Then a tapered cast iron plug coated with sealing compound is inserted in the hole, and an overlapping hole is drilled, threaded, etc. This procedure has been in use for at least 50 years that I can remember, probably a lot longer.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!