Mercury - Gasket Engine Sealing Component Marine-Grade Fiber Composite 879014. Overview. Any seasoned boater knows that a dependable seal can make or break a day on the water. A simple gasket carries more responsibility than most people realize, especially on older Johnson and Evinrude outboards where every joint and seam matters. This Mercury Marine gasket gives you peace of mind the moment you tighten it into place. It feels sturdy, precise, and ready to stand up to long weekends of exploring