Join Date: Jan 2002
Location: Western Canada
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Rep Power: 14
Black Exhaust Stains On Transom
I took a diesel maintenance course a few years back. the instructor was not impressed with how sailors treat diesel engines--he wanted us to run them nearly wide open and under load and long enough for them to get hot. We run them at low rpm, which means the Advance of about 17 degrees is wrong and the burn is inefficient. We run them cold, just enough to get out of the harbour. I think carbon buildup is the cause of the black and the solution may be 6 hours of running the engine at near maximum rpm. the problem with that, as we explained to the instructor, was loading up the prop and drivetrain because you are then trying to push the boat faster than hullspeed, which is not good for the rest of the system. Mine gets an "Italian Tuneup" twice a year, it is a 1984 raw water cooled Volvo and it runs fine.