Sierra 18-2727 Exhaust Water Shutter 3 Inch Rubber Flapper

The Sierra 18-2727 Exhaust Water Shutter is a marine engine exhaust component designed to prevent water from entering the engine through the exhaust system when the engine is not running. This external flapper-style shutter installs in the exhaust line and provides reliable one-way flow protection.

Key Features:

• External flapper design allows exhaust gases to exit while blocking water backflow
• Durable rubber construction resists saltwater corrosion and marine environment exposure
• Compact dimensions: 3 inches in length x 3.780 inches in width
• Direct replacement for worn or damaged exhaust shutters
• Helps prevent costly water damage to engine components

This exhaust water shutter is an essential safety component for inboard and sterndrive marine engines, particularly important when the boat is moored or stationary. The rubber flapper automatically closes when exhaust pressure stops, creating a seal that prevents waves, wake, or rising water levels from entering the exhaust system and potentially reaching the engine cylinders.