cross posted to the engine forum for looks
Well my luck finally ran out after 8 years or so with my boat....here's the story.
I let my friend use the boat whenever he wants and while it happened on his watch I am pretty sure it could have happened to me.  Only thing I wish is I could have been there to understand a few more of the symptoms leading up to the failure.
He had been cruising the lake stopping and starting a few times just admiring the leaves late season.   Last stop he turned off the motor without pulling it out of gear ... not the way I would have done it but I have done it that way as well.  sounded like it dieseled  quite a bit (running on) then shut off.   20 minutes later no start...said it would turn and stop sounding like a dead battery....was close to the dock and got towed in.
I went to boat 2 days later and it would turn over followed by a loud metallic clunk and stoppage of engine...I felt the flywheel/starter was the issue.  oil was clean and no obvious external engine damage or leaks noted
Pulled the plugs today and rotated motor by hand, water came out of a few cylinders, others smelled of raw fuel and were wet....the starter is actually broken  (see photo) suspect the torque from attempting a start after it was locked caused that..
So I don't really know all the systems of hydro-lock but it sure seems like thats what happened.  Questions are where to go now.
I figure best case scenario water came in after stopping the boat.  Worst case water getting in through manifold/gasket.  The boat has not been overheated and was running pretty darn good prior to this.
I think a compression test to rule out any major cylinder damage...with clean oil I am fairly confident I may be ok there.  I fogged all cylinders and pulled the engine through again to try and get rid of any moisture...I doubt I will run the motor this year which concerns me a bit..time will tell if I can get it back together and run it before winterizing.
To top it all off and what sounds like the most troubling issue is I broke a $#)!T%@ starter bolt removing the starter.   I will research some videos and such but that seems like it will be a royal pita to remove the stud.....I heated it up and took my time knowing it was a problem and still F'd it up...argh.  flywheel looks good as well.
Thanks for reading my ramble....open to all thoughts and opinions.
Untitled by 
Jon Miller, on Flickr
 
					
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Jon Miller
1998 four Winns Horizon H200
Volvo Penta 4.3 GL
Newtown, CT
untitled-545 by 
millerjont, on Flickr