Yanmar 2GM20F Burning Oil

[Neo]

The 1987 Yanmar 2GM20F in my Pearson31 burns 8 ounces of oil (240 ml) per 8 hours run time. It also makes a very loud tapping noise when first started. I bring the revs up to 1000 rpm as soon as it starts, and the tapping goes away, I presume because the higher revs get the oil circulating. Once warmed up and running at about 2100 rpm, I can see some smoke coming out the exhaust, if I look closely.

I know I should be running her at 2600-2800 rpm, but 2100 seems to be the sweet spot, and I don’t want to push it considering the previously stated issues. And at higher revs, the boat tends to vibrate more than I’d like.

Is burning oil, in and of itself, an issue? She starts right up, and makes about 4.3 knots at 2100rpm.

Is the burning of oil related to the tapping?

First boat, first diesel, and not sure what to do?

[sabray]

How many hours on the engine? I am guessing that rings/ cylinder sleeves need replacing. Basic rebuild. Hope I am wrong.

[Neo]

This yanmar did not come with an hour meter, so no telling the hours. But it's in a sailboat in New England, so I don't think it has more than 3,000 hours.

[djmarchand]

That it starts right up is good. Implies rings are good. So oil burning may be through valve guides. Post your symptoms on boatdiesel. Ski or someone may have a simple test to isolate valve guides as the problem.

Then rebuild top end if so. Fairly easy for a DIYer.

David

[Neo]

Originally Posted by djmarchand

That it starts right up is good. Implies rings are good. So oil burning may be through valve guides. Post your symptoms on boatdiesel. Ski or someone may have a simple test to isolate valve guides as the problem.

Then rebuild top end if so. Fairly easy for a DIYer.

David

Many thanks, David. I wouldn't mind getting my hands dirty for a change. I'll post on boatdiesel as you suggest.