Sierra 18-4457 Marine Exhaust Protector Valve 4 Inch

The Sierra 18-4457 is a compounded rubber flapper valve designed to prevent water from entering the exhaust system of marine inboard and sterndrive engines. This exhaust protector helps prevent water from backing up into the exhaust system in following seas and when maneuvering astern, providing critical protection against engine damage from water intrusion.

Key Features:

• Constructed with weather-resistant EPDM rubber with UV stabilizer for long-lasting durability
• Designed for use on 4-inch through-hull exhaust outlets and fits 4-inch O.D. exhaust tube
• Includes stainless steel clamp for secure installation
• Size: 4 inches or 101.6mm
• Heavy-duty rubber construction for reliable operation in harsh marine environments

Replaces OEM Part Numbers: MerCruiser 12644Q01 and 12644A1, GLM 89250, Mallory 9-44001. This direct replacement part meets or exceeds original equipment specifications and is compatible with MerCruiser, OMC, Volvo Penta, Chris-Craft, Chrysler, Crusader, and Pleasurecraft marine engines.