I own a 2003 Centurion Cyclone (v-drive) with a mercruiser 350 MAG MPI (5.7). I have approximately 380 hours and do not drive the boat aggressively. I dropped the boat in the water in early June and was running back home to beat a storm. During the initial run I noticed the boat was starting to run rough and ultimately the engine stalled at which point I noticed smoke coming out of the engine compartment. Turns out my mechanic did not hook up all the hoses after witnerization and it fried the wet exhaust system. My mechanic owned up to the mistake and replaced all of the hoses. I dropped the boat back in the water in late June. I ran the boat for exactly one tank of gas. Literally after filling up I noticed a knocking in the engine as I accelerated and that knocking continued to get louder the faster I went. I pulled the boat out of the water and brought back to my mechanic. He tells me I "spun a bearing" and that he reccomends a rebuilt replacement motor.
I asked if the spun bearing was related to the overheat issue and he said "no they are independent issues". I am not a mechanic, but I have to beleive that the overheat may have caused this or be related to this issue. Thoughts?