After cleaning the ring grooves of a piston, what would you use to check the top ring groove for wear?

To assess wear in the top ring groove of a piston after cleaning, utilizing a groove gauge along with an old piston ring is an effective method. The groove gauge allows you to measure the depth and width of the ring groove, ensuring it is within specifications.

Using an old piston ring helps because it can give a consistent reference for how the groove has worn over time. The old ring, which has already been subjected to the mechanical stresses of the engine, will closely match the actual fit and wear characteristics. When placed into the groove, you can evaluate the fit and see how much clearance there is between the ring and the groove, indicating whether excessive wear has occurred.

Other tools such as a tapered gauge or micrometer might not provide the immediate context needed for the specific wear patterns in the groove. Similarly, a new piston ring might not fit properly within a worn groove, leading to inaccurate conclusions about wear. Therefore, using a groove gauge in combination with an old piston ring provides a practical and reliable method for checking wear in the top ring groove.