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Old 02-13-2020, 08:39 AM
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Quote:
Originally Posted by ndutton View Post
If that were the case wouldn't it happen every time the engine was used? Since the boat came from the factory?

No, your cooling system pressure tests and compression test confirm everything is intact, your exhaust system drawing tells us it is properly done and your assertion the raw water thru-hull was closed during prolonged cranking eliminated backflooding through the exhaust as the cause of your watered down oil. So what's left? How did water get into the oil?


You have enjoyed 200 hours of trouble free motoring until this episode (save slightly elevated temperature) and now all of a sudden there is water in the oil. Cause and effect. You should probably check the anti-siphon valve for proper operation too.

About the elevated temperature, I suggest it is probably time for a heat exchanger disassembly and cleanout. While you're at it you might consider MMI's new thermostat too.
I am going to agree with you about 98%. I doubt the boat has been flooding the engine since new as well. One thing I have found out the hard way is some hose runs are critical to the inch and it doesn't take a lot to put a new hose "almost in the same place" and cause a problem you did not have before.
That long exhaust hose run to the stern would be one such run. The high section running aft will do fine with a slight slope going down as it goes aft and if rearranged to have the aft end slightly higher will send a lot of water running back to the water lock. This could make a hard-to-start engine much more prone to flood. I would check this run and make sure it has not gotten loose or moved in such a way that would encourage flooding. IMHO
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