SpankDog

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PatriYacht

If you are damaging that many engines in that short a period of time, something is wrong with your set-up. Normally these engines run for hundreds or thousands of hours with minimal maintanence. A piston can't hit a sparkplug. It never gets that close. A piece of a piston can break off and then hit a sparkplug. Causes for something like that could be overheating, too much ignition timing, lean fuel mixture, lousy low octane gas. The most recent bent sparkplug means that something loose flew thru the engine again. Another piece of a piston? Maybe. I doubt this is Mercruiser's fault but you can try to get them to replace it. For sure I would find another mechanic. It's far more likely that he set up something wrong or there is something wrong with your boat that he hasn't found.

SpankDog

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BillK

Spanky,
Detonation will do that type of damage to the sprak plugs. Has anything been done to the carburetor during all of these engine replacements ? If it is the original from 1992, it at leasts needs a rebuild / freshen up and probably could just stand to be replaced. Has the ignition system been tested to see if the advance system is working properly ? I dont actually work on a lot of the actual boats but seem to remember some issues with the Mercruiser ignition boxes failing in a full advance mode.

The other issue I see is that if you are not using the biat very often the fuel can be going "stale" also causing detonation. Modern fuels just dont seem to have much of a shelf life. If you are only using the biat a couple of times a year, then you definitely need to be adding a fuel stabilizer.

I also think you might need to find a different mechanic, one who has the knowledge and the equipment to properly troubleshoot the entire installation.

Just my opinion,

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

SpankDog

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jeffswav

Sorry about your problems. I have been there and I know how it feels. I do all my own wrench work however I have a machine shop that I use for the major work. I am not an engine builder but I have 100's of hours working on my own equipment. I could be somthing simple like connecting the oil lines backward. There is also valve on the filter pad that may be incorrect. Make sure they use the 30psi valve. There is a good post on oiling systems I put it to the top for you.

SpankDog

Thanks again. I am going to check out the boat again today. Going to check all the plugs and maybe do a compression test. I tried searching but I couldn't find a diagram of the oil lines, I'd like to check and make sure ours are installed correctly.

SpankDog

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SpankDog

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