No, it did not happen at full throttle. We were out on the lake and hit a rock, dinged up the prop pretty good. Switched prop for the same exact prop (pitch and diameter) but boat would not idle or go above 3000 rpm's under load. Prop shaft is NOT bent. The flywheel does not have a pin that could have sheered to mess up timing. Anyway, being the dummy I am, I adjusted the idle a bit so it would stay running at an idle and allow me to get back to the dock. Well, on the way into the dock the motor would not come out of forward gear, and then all of a sudden it clunked into neutral and stopped the motor dead. I was only going at about 1500-2000 rpm's at the time. Then it would not start again. As part of my investigation of this, I discovered the flywheel would not spin all the way around. Upon further looking I see that all 6 pistons are moving when I turn the flywheel, but after about 7/8th of a turn is seems to hit something that prevents it from spinning any further. Same thing when I spin prop. In neutral the prop spins freely, but flywheel still stops. In forward and reverse the prop spins the flywheel up until it hits that same stopping point. Haven't drained gear lube yet to look for water in it. I plan to remove the lower unit and see if flywheel spins with lower unit off. If not, what could it be in the upper part, if all pistons are moving with flywheel? How do I go about inspecting the rods, crank, or pistons to see if the issue is there?