A worn counterbore can lead to which issue?

• A. Excessive sleeve protrusion
• B. Piston damage during installation
• C. Sleeve cavitation
• D. Upper sleeve flange separation

Answer: (D)

A worn counterbore affects how the cylinder liner sits in the block and how the upper flange of the sleeve is supported. The counterbore provides a precise seating surface that keeps the sleeve positioned and the flange pressed against its mating surface. When that seating surface wears, the liner isn’t held as tightly or as accurately, and the top of the sleeve can lose its proper support. Under operating pressures, heat, and vibration, this reduced support can allow the upper sleeve flange to separate from the rest of the sleeve assembly. That separation is the failure described.

Excessive sleeve protrusion would come from improper depth or seating rather than wear of the counterbore, piston damage during installation isn’t a direct result of counterbore wear, and sleeve cavitation is related to cooling flow, not the mechanical seating issue caused by a worn counterbore.