Cylinders are deglazed to ensure proper ring sealing.

• A. To increase compression ratio
• B. To improve lubrication
• C. To ensure proper ring sealing
• D. To reduce carbon buildup

Answer: (C)

Deglazing a cylinder bore is about making sure the piston rings can seal properly against the wall. After honing, the bore should have a controlled cross-hatch texture that helps rings bed in and hold a thin oil film. If the bore becomes glazed—smooth and glassy—the rings won’t grip or seal well, leading to blow-by and a loss of compression. Deglazing removes that glaze to restore the rough surface, re‑establishing the conditions for the rings to seat and seal effectively as the engine runs. While the roughened surface can aid oil retention during break-in, the main purpose is to ensure proper ring sealing. It doesn’t change the compression ratio, nor is it primarily about lubrication or directly reducing carbon buildup.