🔍 Key Concepts

• Function of piston rings in a two-stroke diesel engine (sealing vs. lubrication vs. heat transfer) • What black discoloration on a sealing surface usually indicates (think combustion gases vs. oil film) • Meaning of blow-by and how it affects ring and liner surfaces

💭 Think About

• Ask yourself: What has to happen for combustion residue to reach and stain the sealing surface of the rings? • Which condition would most likely allow hot, dirty gases to pass the rings rather than stay above the piston? • Which of these choices mainly affects temperature or load, and which one directly affects sealing between piston and liner?

✅ Before You Answer

• Be clear on the primary symptom: black areas on the sealing surface, not just general wear or scoring • Match each option to its direct effect on ring/liner contact and gas sealing, not just overall engine health • Decide which condition most strongly suggests combustion gases leaking past the rings rather than only heat or lubrication issues