Mercury Tappet Bucket - 8M0142491. The Mercury Tappet Bucket 8M0142491 is an essential OEM part for maintaining proper valve clearance and smooth engine timing in your Mercury marine engine. Crafted for durability and precision, this tappet bucket ensures optimal camshaft-to-valve interaction, helping your engine run quietly, efficiently, and with reduced wear over time.. Key Features. Genuine Mercury Marine Part - Identified by part number 8M0142491 for accurate OEM replacement. Hardened Constr