Yanmar GM1 Black Exhaust

[rogerowen]

My ultra reliable and very easy to start inboard has a hard life pushing my rather heavy Robert Ives 21' sailing boat. All is fine except when pushed - and we can see the stuff coming out of the exhaust is very black. Back off the throttle and it clears again after a while. Any ideas ? Thanks.

 

[westernman]

Overloaded. You are probably over-propped.

If you are not getting maximum rated rpms on full throttle, then you are over propped. It is then probably worth getting the prop adjusted. This is easy for a professional to do and not expensive.