Where is the greatest amount of cylinder wear typically found?

Where is the greatest amount of cylinder wear typically found?

• A. Near the top of the ring travel area
• B. At the bottom of ring travel area
• C. In the middle of the bore
• D. On the piston crown

Answer: (B)

Cylinder bore wear is controlled by where the piston rings actually rub against the bore and how well the oil film is maintained there. The bottom of the ring travel area tends to experience the most sliding contact and the oil film is harder to keep thick there, especially as the piston moves toward the bottom of the stroke. That combination—more ring-to-bore rubbing and thinner lubrication—produces the greatest wear in that region. The top portion of the bore is hotter and under high combustion pressure, but the oil film can still be more effectively driven toward the top, and the wear from rubbing isn’t as severe there. The middle of the bore sees less extreme rubbing than the bottom, so wear is less there. The piston crown itself isn’t a bore surface, so wear there isn’t counted among cylinder bore wear.

Cylinder bore wear is controlled by where the piston rings actually rub against the bore and how well the oil film is maintained there. The bottom of the ring travel area tends to experience the most sliding contact and the oil film is harder to keep thick there, especially as the piston moves toward the bottom of the stroke. That combination—more ring-to-bore rubbing and thinner lubrication—produces the greatest wear in that region. The top portion of the bore is hotter and under high combustion pressure, but the oil film can still be more effectively driven toward the top, and the wear from rubbing isn’t as severe there. The middle of the bore sees less extreme rubbing than the bottom, so wear is less there. The piston crown itself isn’t a bore surface, so wear there isn’t counted among cylinder bore wear.