Oil in exhaust?

[dmksails]

My Yanmar 3GM30F with 1040 hours normally runs great with no smoke except at startup. I've just completed a short trip where I motored for 6 hours. During 3 of those hours I was towing a 30-ft sailboat with a very dirty bottom. During the trip I did not notice any smoking from the engine. Once back in port I notice a dark stain flowing down from the exhaust. I checked the oil level and it appears to be the same as when I left. Do I need to be concerned about this and if so, what do I check?

[tkeithlu]

I doubt that on the basis of what you described that you have much of a problem. It looks like normal soot, and it would be better that you engine not produce any, but under load it may. Ever seen an 18 wheeler accelerate and send out a monster black cloud? Same "problem," but much worse.

[a64pilot]

Towing a heavy boat is similar to being over propped, that and most Yanmar’s are famous for not burning all their fuel cleanly.
I don’t think you have a problem, if your concerned I’d take the injectors in to be tested and cleaned, that can’t hurt especially if you don’t know when it was last done.

[jimbunyard]

Turn on all your lights and run it at about 3000 rpm in neutral for about 10 minutes?

[Compass790]

Originally Posted by a64pilot

Towing a heavy boat is similar to being over propped, that and most Yanmar’s are famous for not burning all their fuel cleanly.
I don’t think you have a problem, if your concerned I’d take the injectors in to be tested and cleaned, that can’t hurt especially if you don’t know when it was last done.

Wot he said,
Pretty much you were over-fuelling frm too much load so more fuel was getting injected into yr cylinders than could be burnt with availiable air.
Once yr diesel engine starts blowing black smoke you need to back off on the throttle.