There is an easy solution than you've tried. That is to use blower and clean your outboard motor with that blower. It would really help you in solving your problem.
Can You Fix An Outboard Motor That Has A Cracked Block?
Sleeves the block but depend on were tha crack is you can weld but tha best thing is just to replace it
No you can't. Call twinn outboard they have parts for any motor they are in minn st my name is dennis