how can i weld the starter back onto mercury boat motor?

i can only assume you mean weld a part on your starter,you need to find a good welder with a heliarc welder,he will know what and how

I never saw a starter welded on to an engine before, but I have self-engineered a few unconventional solutions to other problems so I kind of understand the concept.

If you really want to weld it on there, just follow this simple 3-step process:

1. Buy, borrow or steal a welding machine.

2. Take a class, or otherwise find a welder to teach you how to weld.

3. Weld the part on to the motor.

Sorry, welding's not a do-it-yourself gig, unless you happen to be a welder.

IF all else fails then find a College or Junior College that teaches Welding. Aluminum takes special welding and then there are other materials. Instructors know how to weld and students may weld it but it won't be welded till they have the technique mastered!

That's odd, usually starters are bolted on, for the obvious reason that they sometimes break down. Sometimes they need to be replaced.

I wouldn't recommend welding it on unless it looks like it came that way from the factory.