Yanmar 2GM20F blew oil/fuel out exhaust

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Yanmar 2GM20F blew oil/fuel out exhaust

Postby lee » Wed Jul 05, 2017 10:37 am

I was coming out of a harbor when I cranked up my Yanmar 2GM20F a little higher than normal (cruising at approx 5 knots with growth on hull). at the worst moment (busy inlet) my motor blew a bunch of oil (all over my new dingy but that's another matter ) out the exhaust. I turned the key off and proceeded to put up the sails in about a knot of breeze. I was having trouble finding a breeze to fill my sails, but the boat was inexplicably tracking well. It took me a minute to notice that the motor was still running as I had instinctively turned the key instead of starving the fuel. It was no longer leaking any oil so after a time and enough wind for steerage, I turned the motor off, checked the oil and added a tiny bit, tuned the motor back on and limped home at half speed (3.o knots motorsailing) for about 6 hours.
The motor never gave me any trouble after that. Checked the oil and kept an eye on the exhaust port but the engine behaved fine the rest of the trip.
I am told that sometimes unburnt fuel can build up in the engine and then let go at once? Any other ideas about how oil or fuel can get shot out an exhaust?
lee
 
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Re: Yanmar 2GM20F blew oil/fuel out exhaust

Postby GeoffSchultz » Wed Jul 05, 2017 6:03 pm

What was the consistency of what it blew out? Are you sure that it was oil and not carbon?

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Re: Yanmar 2GM20F blew oil/fuel out exhaust

Postby lee » Thu Jul 06, 2017 11:42 am

Thank you for replying Geoff. I have since come to the conclusion that it was in fact Carbon. This is my first inboard diesel and after talking to several people and going over the consistency of what we cleaned off the digny I am sure that was the case. Its a long learning curve but we are making progress. We are having a great time with the boat.
How are you making out?
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Re: Yanmar 2GM20F blew oil/fuel out exhaust

Postby GeoffSchultz » Fri Jul 07, 2017 5:15 am

Glad to hear that you think that it was something benign. There may have been a build-up that accumulated in the muffler or in the exhaust elbow. You may "want" to pull of the exhaust elbow and check it for build-up and clean it.

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