Exhaust Flapper 4″

A 4″ marine exhaust flapper valve and clamp assembly designed to help reduce backflow into your exhaust system in rough-water situations.

Key Features

• 4″ exhaust flapper valve assembly
• Weather-resistant rubber flapper valve
• Includes stainless steel hose clamp

Product Compatibility

• Marine exhaust systems (exhaust mufflers/flappers and related hose connections)
• Gasoline or diesel sterndrive/outboard installations that use an exhaust flapper design

Product Details

• Sierra Exhaust Flapper 4″
• Part/Model on listing: 47-4457
• Includes stainless steel hose clamp
• Weather resistant rubber flapper valve
• Size: 4″

Parts Desk Insights

Best Use Case: Use this flapper when your exhaust system needs a replacement one-way (flapper) valve at the outlet/connection point to help discourage water from entering during following seas or when backing down.

Common Issues: Common failure points for flapper-style valves include rubber deterioration and reduced one-way sealing over time. If youre replacing it, inspect the mating hose/exhaust connection for cracks, wear, or corrosion and confirm the hose diameter matches the 4″ application before tightening the clamp.

Related Products & Accessories

• Exhaust Systems – Browse the Exhaust Systems collection for related exhaust hoses, mufflers, and flapper components.