Engine Welding

I need to get a piece welded on my engine I was wondering if anyone has had that done before?  Does it mess it up?  Would I be better off buying another engine?

My buddy has a JB welded crank case on his 929. It leaks a little oil if you are on it for long periods of time, but so fars its alright. I dont kow why he didnt just get a new one though.

i broke an engine mount off the block last year and i took it to a autobody shop and it cost 200.00 to get it welded back on..
 
make sure that whoever does it can weld aluminum.. and if its near seals,gaskets or bearings it will have to be disassemled because of the high heat that it takes to weld..