Join Date: Dec 2013
Location: Tampa FL
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Re: Yanmar baffling black smoke
I have a Yanmar 2GM20 and am also blowing black smoke and dropping spots of black onto the water, but only when at revs over 2100. Too much smoke for it to be related to carbon build up. I noticed that my oil level is 20% over the 'full' mark. could this cause the black smoke etc?
It could be excess load on the engine at that RPM. Does it do that in neutral and in gear, or just in gear. If only in gear it could be that your prop is over-pitched, or you have something wrapped around the shaft, although the latter would most likely have an effect at any speed.