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Yachtwork, Marine Engineer
Category: Boat
Satisfied Customers: 1048
Experience:  MEC3 and RYA Yachtmaster Ocean
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I work on a yacht that has 2 detroit diesel 16v92. The port

Customer Question

I work on a yacht that has 2 detroit diesel 16v92. The port main has a higher load and GPH then the starboard main and blows out a lot of black smoke from the exhaust. Injectors are all working and all pistons are firing good. We have hire several different companys to try to figure out the problem with no success. If there is something we are over looking please let me know.
Submitted: 6 years ago.
Category: Boat
Expert:  James replied 6 years ago.

Hello, welcome to JustAnswer.


Is the fuel pressure the same on both motors? Are the propellers the same pitch and diameter on both motors?

Customer: replied 6 years ago.
Yes the fuel pressure is the same and the props have the same pitch.
Expert:  James replied 6 years ago.
And they are the same diameter?
Customer: replied 6 years ago.



Expert:  Yachtwork replied 6 years ago.
Hello- Thank you for asking. I have some other ideas that may help. The engine using the excess fuel is blowing back smoke. That is unburnt fuel as also shown by the extra fuel use. The reason will be-
  • a bad injector
  • clogged air filter
  • low presure turbo (bad turbo- if you have a TE version)
  • blower seal blown
  • clogged intercooler, if fitted
Start by pulling the air filter and testing again. You can also pull the valve covers and hold down each injector one at a time listening to sound of the engine making sure each "dips" in rpm's the same as the other cylinders. This will show the bad injector. The turbo has a port to check presure. You don't say what 92 you have, but the presure will be about 1.5 bar. You can check compaired to the other engine. If you have an intercooler (TI series) then if all else fails pull it and make sure it's clean. Detroits tend to foul intercoolers when a turbo seal blows a bit of oil.

Lastly if you look in the Detroit manual they give about 20 test points on the engines . Use these if you run out of other ideas.


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