Yanmar 35 HP - 3HM35F
The Yanmar diesel on our boat produces black smoke and emits black suit mixed in with the water from the exhaust when we do rapid forward and back manoeuvering, such as backing up into a slip.
The engine does not burn any oil nor does it show any symptom of malfunction. The oil and coolant level are all normal. Other than the issue described in the first paragraph, the engine works perfectly fine.
Is it normal to have black smoke and black sludge coming out of the exhaust when conducting rapid manoeuvering? If not, what can be done to rectify this?
Any advice is greatly appreciated.