You suspect that a diesel generator set on your offshore supply boat has a misfiring cylinder because the engine, although warm, is running roughly. The six-cylinder engine is fitted with a high-pressure distributor type pump with hydraulically operated injector nozzles. When you slacken the high-pressure fuel line at #4 fuel injector nozzle, the engine runs even rougher than before. Upon re-tightening the high-pressure fuel line fitting, the engine reverts back to the original roughness before the fitting was slackened. What does this indicate?
• Diesel engine cylinder cut-out test – what you learn by loosening a single injector line • Effect of removing fuel from a good (firing) cylinder vs a bad (misfiring) cylinder on engine smoothness and speed • How a multi‑cylinder engine shares the load among cylinders
• When you slacken an injector line on a cylinder that is working well, what should happen to engine smoothness and RPM? Does it usually get better, worse, or stay the same? • If you slacken an injector line on a cylinder that is already not contributing (misfiring), how much additional change in roughness or RPM would you expect? Why? • Based on the scenario, did loosening #4 make the engine contribution from that cylinder better, worse, or unchanged? What does that imply about #4 compared to the others?
• Be clear whether the test is removing fuel from that cylinder or adding fuel to it. • Think about whether the engine got more rough or less rough during the test and what that says about #4’s contribution. • Verify your logic: if #4 were already dead, would loosening its line be expected to make a noticeable additional change in how the engine runs?
No comments yet
Be the first to share your thoughts!