🔍 Key Concepts

• Heat expansion of piston rings and the purpose of ring end gap • How contact patterns (where shiny/bright spots appear) reveal where parts have been rubbing or striking • Difference between overall wear around the ring vs. wear concentrated only at the ring ends

💭 Think About

• Ask yourself: If the only bright or shiny areas are right at the two ends of the ring, what does that say about which parts have been touching or striking each other? • Consider what happens to a ring as it heats up in the cylinder and expands—what part of the ring will close first, and what if there is not enough clearance there? • Compare which choices would cause wear all around the ring surface versus only at the ends of the ring.

✅ Before You Answer

• Verify which condition would cause the ring ends to touch or collide with each other as temperature increases • Check which listed fault would most likely produce localized bright spots at the ring tips, not uniform scoring or polishing around the full circumference • Eliminate any option that should produce generalized wear over the whole ring face rather than just at the two ends