🔍 Key Concepts

• Function of piston compression rings in sealing combustion gases and controlling lubrication • How chrome-plated rings wear and what discoloration patterns usually mean • Relationship between blow-by, wear limits, and visible ring face condition

💭 Think About

• Think about what a blackened area on the ring face at the ports tells you about where the ring is actually making contact and sealing. • Ask yourself: if the ring were badly worn or allowing excessive blow-by, would you expect a uniform color, or a specific pattern at the port openings? • Consider what a ring in truly good condition should look like after some service: would it be bright all around, or have a distinct ‘seat’ or contact band?

✅ Before You Answer

• Compare the meaning of a localized black band at the ports versus overall ring face discoloration. • Review what a crown-face (barrel-faced) ring is supposed to do in terms of contact area with the liner. • Verify which option best matches a normal, expected contact/wear pattern rather than a failure or excessive wear indication.