Exhaust Flapper 4"
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
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 you’re 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.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.