Rumbling Mercury

I have a 2006 Mercury Elpto 90 hp that belonged to George Bush Sr. It got damaged in a summer storm and the engine got salt water in it with only 2 hours on the motor. It was flushed and run, then left idle for a year. When I got it, the crank had a tight spot when turning it with a wrench. I have put double oil in it from the start and it ran well for 9 months. Last week was the first tank of fuel which only had the normal 100/1 oil mixture in it. The engine started to make noise and by the time I got back to my main boat at idle speed, it was making a lot of racket! I figure that the top bearing froze up and spun. Does this mean that the bearing housing ie: the crank case is shot? Any one out there gone through this?
Wayne

Re: Rumbling Mercury

100:1?
I thought most all boat motors run 50:1 when on premix. Very likely spun or burnt bearing. Sounds like tear apart time. May be able to save it if all that happened is a bad bearing.