When inspecting pistons, liners, and rings of a large two-stroke/cycle diesel engine through the cylinder ports, a wet piston crown would indicate a __________.
• function of fuel injectors vs. lubricators in a two-stroke diesel • where lubricating oil is normally applied (liner vs. piston crown) • symptoms of ring failures (compression ring vs. oil control ring)
• Ask yourself: what liquid is most likely to be found on the piston crown itself—fuel or cylinder lubricating oil? • If a ring fails, where would you expect to see abnormal oil or blow-by—on the liner walls, in the crankcase, or directly as a wet crown? • Which component, if not working correctly, would allow liquid to drip or spray into the combustion space even when it should be properly atomized or controlled?
• Be clear on the normal path of cylinder lubricating oil in a large two-stroke (it’s aimed at the liner, not intended to pool on the crown). • Recall the typical sign of a leaky injector—what does poor atomization or after-dripping do to the piston top? • Remember that a broken compression ring mainly affects sealing/compression, while a faulty oil ring mainly affects oil control on the liner, not primarily on the crown.
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