I don't post much on here. I have a Mercruiser 350 that was in my Ultra but the impeller imploded. Trying to limp back to the dock I believe i sucked water through the exhaust. Tried to fire it a couple times loud screeching and grinding noise. Sounded like the starter engaging but the fly wheel not budging. Pulled all the plugs and turned it over and water came out of 3 or 4 of the cylinders. After that i couldn't get it fired up. Pulled the motor out brought it home and tore most of it down cant turn it over by hand with the plugs pulled. But I just don't have the time right now I need to find a good reputable engine builder to find out whats wrong and rebuild it nothing fancy. I live in the OC area.