Frank, a couple more things to add to your check list for diagnosing smoke at cruising speed: One is poor fuel quality or gunk (water, diesel and algae) in your tank. Changing fuel and replacing filters is an easy way to rule this out. The second is a rusted exhaust mixer on Yanmar GM series engines. They clog up and cause back pressure especially in salt water. The back pressure causes poor combustion and black smoke. You can get a stainless steel replacement mixer on eBay.
Cheers, Will Harney Disco Volante C&C 35-2 #351 _______________________________________________ This list is supported by the generous donations of our members. If you like what we do, please help us pay for our costs by donating. All Contributions are greatly appreciated!
