I think my frustration is that to me pitting in cylinders are not the cause of water its the result of. The repair i think was a headgasket and maybe even manifolds. Headgasker probably could have been done and ran without water getting in the cylinder. My non marine experience opinion. I feel the bore and balance rotate assembly was above and beyond and not needed to grt it back out on the water

Well had a call with an attorney today he suggested let them finish the work..give them a check for what he quoted and let them take me to litigation even though he said they will not find anyone to take the case since they have nothing in writing..not sure if I like the idea..although I don't think I owe him for the work I never authorized. Thoughts?

Question is, will he release the boat back to you if it's not paid in full?

If you can grab the boat, take it and let him keep the motor........but I strongly suspect the guy won't release the boat.

I'd let the mechanic keep the motor and spend the money on a new one instead.

Throwing good money out the window twice.............Lawyer will get his fees and you likely won't get a judgment that collectible (if you even get a judgment)

In what state did this occur?

In order to get the boat in your possession, insist that you take it and sea trial it. Once you physically have the boat it will tilt the advantage towards you.

My assumption is that cool heads will prevail and there will be a number someplace between the original quotation and the "final" invoice that will work for both of you. You will both take a haircut, no doubt, but it will be behind you and you will not waste any more time or emotion on it. If the original quote was $3k, and he wants $10k, if you meet someplace in the middle it will cost you an additional $3k or so. Most small business guys are "cash flow challenged" so there is incentive on his end to settle up. It will take you less time to go earn the $3,000 than to deal with it.

My day used to remind me at times that in order to keep somebody else down, you gotta stay down there with them. Have the conversation, get it settles and move on.

I highly doubt your engine "didnt" need the work thats being done to be right BUT for a shop to go from a 3000$ quote to 10,000$ WITHOUT AUTHORIZATION is crazy. Clearly they dropped the ball. At some point did you tell them "its broken, I just want it fixed, do whatever it takes"?? Even then, they should have gotten authorization before going further as everyone has a budget and as you mentioned, you would have just bought your friends 496. Laws vary greatly between states, alot of people in Michigan that are vaguely familar with the bureau of auto repair mistakenly think it covers boats and it does NOT whatsoever for example.
At my shop in Michigan, IF you dropped your truck off for repair, I told you 3000 to fix it, you agreed in writing, I did NOT call for authorization beyond that then called and told you your final bill was say 6000, one phone call to the state from you and they would be here ripping thru my work orders like a hyena. Handing out 1250$ fines for every tiny clerical violation in paper work on every job Ive ever done, force me to give you your vehicle without paying the extra, IF you did pay me to get it, they would make me reimburse you triple the overcharge and again fine me for every vehicle on property with work in progress that does not have perfect work orders, etc.
Now when it comes to a BOAT, they wouldnt care whatsoever because its not a registered road vehicle and would tell you too bad, theres no one at the "state" here in Michigan that will do anything for a boat customer. You would have to sue me, its possible if your work was done and bill was higher then you agreed to in writing and you called the sheriffs department and said I wouldnt release your property, they may force ,e to give it to you but they typically wont get involved and will tell you "its a civil matter".

The thing I worry about is that you will end up with a mechanic's lien on the boat, and end up losing it. Get the boat out of their possession ASAP.

This ?