In engines with chromium-plated cylinders, piston rings must not be chromium-plated.

In engines with chromium-plated cylinders, piston rings must not be chromium-plated.

• A. Chromium-plated
• B. Steel
• C. Bronze
• D. Not chromium-plated

Answer: (D)

When a cylinder wall is chromium-plated, the surface is extremely hard and very smooth, which changes how the piston ring must seal and wear. Using chromium-plated rings on such a bore can cause problems because the plated layer on both parts can spall or wear away in a way that chips off into the oil, leading to scoring of the bore and poor sealing. Non-chromium-plated rings—plain rings made from standard cast iron or steel—are designed to work with chrome bores, forming a stable oil film and a proper seal without introducing brittle chromium onto the ring. So the best choice is rings that are not chromium-plated.

When a cylinder wall is chromium-plated, the surface is extremely hard and very smooth, which changes how the piston ring must seal and wear. Using chromium-plated rings on such a bore can cause problems because the plated layer on both parts can spall or wear away in a way that chips off into the oil, leading to scoring of the bore and poor sealing. Non-chromium-plated rings—plain rings made from standard cast iron or steel—are designed to work with chrome bores, forming a stable oil film and a proper seal without introducing brittle chromium onto the ring. So the best choice is rings that are not chromium-plated.