Mercury - Quicksilver V-Belt Engine Drive Belt 40" (1,016mm) 69143Q. Overview. A dependable belt keeps your MerCruiser's systems running in sync - from the alternator to the water pump. The Mercury Marine 69143Q Quicksilver V-Belt is a 40-inch (1,016mm) OEM replacement belt built for MerCruiser sterndrive and inboard engines. It's made from durable, reinforced rubber that stays flexible under heat and load. Designed to the same specs as the original factory belt, it provides quiet, steady power