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Problem. Twin Yanmar 75hp diesels in a Seaward 25 displacement hull. Up to 2300 rpm no worries, runs like a sewing machine but over 2400 rpm huge black smoke from BOTH engines and will not go over 2500 (should be 3500 max). With no load the engines both rev easily to 3500. The injectors have been serviced, the hull is clean – relaunched a month ago. We could understand maybe a turbo or fuel pump problem, but on both engines at the same time? The engines have done about 900 hours each. Any suggestions gratefully received.
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How about we start with some easy items. Post some pictures of the engine room so that we can see things. I am particularly interested in the exhaust setup. Exhaust directly runs the turbos and that in turn pushed more air into the combustion system. Black smoke is usually indicative of more fuel than air, so some kind of air restriction. Maybe some kind of restriction that keeps the turbo from spinning. What do the air filters look like?
Pics first then maybe we can figure a more appropriate avenue.
What is your boat speed at 2300 and then what is your boat speed at 2400 when things start to smoke?
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