It's a 1992 Mercury V-6 200 hp 2.5 ltr on a 22-2 AS. I had the boat on the beach to clean the bottom, and I was inspecting the prop for any fishing lines, etc. What I noticed was that there is a 1 1/2 inch long crack under the prop in the prop housing (if that's the term). It's the lower unit's bottom unit holding the prop. The crack starts out less than a millimeter wide, and gets smaller in width, but it (the crack) actually curls and goes for another 2 inches. Can this be welded? Are there any negative effects from this crack - vibration maybe, water getting into the lower unit, etc? Thanks.