18-7170 SIERRA Sealing O-ring Replaces Mercury 25-33504

18-7170 SIERRA SEALING O-RING High-performance elastomer o-ring designed for Mercury marine engine sealing applications. This OEM-equivalent component replaces Mercury part 25-33504, providing dependable fluid retention in fuel injectors, cooling manifolds, and accessory housings. Manufactured from an advanced marine-grade elastomer that resists saltwater exposure, fuel degradation, and extreme temperature variations. The o-ring maintains consistent sealing integrity and compression characteristics throughout extended service life, preventing leakage and contamination. Essential for preventive maintenance, fuel system repairs, or complete engine restoration on Mercury-equipped marine powerplants. Delivers reliable performance and maximized durability in challenging saltwater environments.