Thanks for the inquiry. The motors are Cat 3126TA 420hp. Still have not gotton to the bottom of it but had water/antifreeze intrusion into the #3 cylinder. They think there is a crack in that cylinder but they are not sure. It is however scored too. Also found traces of antifreeze in the oil And traces of oil in the antifreeze. Also oil residue in the antifreeze overflow. No antifreeze in either the tank or the overflow and not much in the motor itself. The guess, at this point that is all it is and will be, is that the turbo or the oil cooler was the cause of the leak and the subsequent overheat likely led to the the block issue. One other issue that is puzzleing, the coolant tank cap when pressure tested failed. However, the day this all came to a head, when I checked the antifreeze level it was good as was the overflow tank. I have never had to put antifreeze in either motor. There was no antifreeze in the bilge and there was not any smoke out of the exhaust. Not sure where all the antifreeze went but it was not in the crank case.
The reason I said that is all it will be is I am not willing to spend several hundred in additional diagnosis money. I know the block is damaged and needs replaced. The head may be as well. I know the heat exchanger is okay as it pressure tested fine. I am getting a reman long block and having the turbo rebuilt. The oil cooler comes with the block. i do not need them to test the head or the oil cooler to figure out if it was the culprit at $85 an hour. At this point I am more comfortable with having everything rebuilt.
The insurance guy is coming mid-week to make a determination if it is covered. I am not holding my breath on that one. The new motor will be here on Friday. With a little luck everything will be assembled and ready by the following weekend. The motor has a one year warranty and I will likely purchase an extended warranty for another year or two.
Going in with the attitude that I know nothing of the history of the starboard motor, I will be taking a pro-active approach on the maintenance and consider that nothing has been done. Over the next couple months I will be removing cleaning and testing all of the components starting with the heat exchanger and oil cooler. I recently had a service done on that motor so I will wait a few hours to do an oil sample. I am also going to flush the anitfreeze on that one since I now have no idea how old it is. Basically everything that is in the service manual short of rebuilding it. I will be following the manual on both motors pretty religously here on out I can assure you.
I do have the basic service manual and am pretty good mechanically. I have seen nothing that I can not service myself (save maybe turbo rebuild or injector rebuild) given the appropriate amount of time. In the end I will know it was done and done correctly.

I had always done all of my own maintenance and repairs on everything from boats to motorcycles and cars. Even worked on a few airplanes back in the day. I had gotten lazy and let other people do it for me the last few years due to committments to other things. I think I need to change that.
Blowing into the teens in boat bucks will have you quickly re-evaluate things that is for sure. Sucks that it happened but stuff breaks. I am just glad I am in a position to afford the cost.
Sorry for the long post but you guys asked.
