We have an old 3 cylinder Yamaha two-stroke on the 15' Boston Whaler and the normally reliable beast recently stranded us for the very first time before magically fixing itself. It has been running perfectly ever since. I think it has an intermittent magneto problem, but can't prove it until it cooperates by malfunctioning.
In a half-hearted attempt to force such a malfunction, we recently took the boat up to Nav-A-Gator, some distance up the Peace River. I say half-hearted because we did ensure that we had a current towing insurance card along. The boat ran perfectly once again and when we got home, I ran it on the fresh water flusher for a bit. The picture at right shows what I noticed.
Judging by the corrosion around the crack, it has been there for a little while, I just haven't noticed it. It's pretty hard to miss when you put on the flushing ears, but I did manage to miss it and only noticed when the engine was running and it was spitting water out the side.
Pictured at left is a closer view of the same crack when dry. Now I'm wondering whether to fix it, and how to fix it. A neighbor knows how to weld. We may just wind up replacing it, not sure...
To be continued, no doubt.