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Description
4" Exhaust Flapper Valve – Fits MerCruiser Stern Drives 1994 & Up (Replaces 12644A1, 12644Q01)4" Exhaust Flapper Valve Fits MerCruiser Stern Drives 1994 & Up (Replaces 12644A1, 12644Q01) This 4" exhaust flapper valve is designed for MerCruiser stern drive exhaust systems from 1994 and newer. It features a compounded EPDM rubber construction with a UV stabilizer to prevent water from entering the engine through the exhaust system, ensuring long lasting performance in marine environments. This part directly replaces MerCruiser 12644A1 and
4" Exhaust Flapper Valve – Fits MerCruiser Stern Drives 1994 & Up (Replaces 12644A1, 12644Q01)
This 4" exhaust flapper valve is designed for MerCruiser stern drive exhaust systems from 1994 and newer. It features a compounded EPDM rubber construction with a UV stabilizer to prevent water from entering the engine through the exhaust system, ensuring long-lasting performance in marine environments.
This part directly replaces MerCruiser 12644A1 and 12644Q01, Mallory 9-44001, GLM 89250, and Sierra 18-4457.
- Material: Compounded, weather-resistant EPDM rubber with UV stabilizer.
- Installation: External mount on 4" exhaust systems with the included clamp.
- Complete Kit: Includes two exhaust flapper valves and two stainless steel clamps.
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| MerCruiser | 12644A1 |
| MerCruiser | 12644Q01 |
| Mallory | 9-44001 |
| GLM | 89250 |
| Sierra | 18-4457 |
Compatible Engine Models
Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | Various Stern Drive Models | Various | 4-Stroke | 1994 & Up | 12644A1, 12644Q01 | Fits 4" exhaust systems |
| OMC/Volvo | Various Compatible Models | Various | 4-Stroke | For 4" exhaust systems |
Technical Specifications
| Specification | Value |
|---|---|
| Product Type | Exhaust Flapper Valve |
| Installation | External, with clamp |
| Size | 4" (101.6 mm) |
| Material | EPDM Rubber with UV stabilizer |
| Connection | Stainless Steel Clamp (4-1/16" to 5") |
| Housing Color | Black |
| Dimensions | 7.25 × 6.75 × 2 in (184.15 × 171.45 × 50.8 mm) |
| Weight | 0.5 lbs (0.227 kg) |
| Warranty | Limited lifetime (Sierra brand) |
Package Contents
- 2 x Exhaust Protector Valve (Replaces 12644A1, 12644Q01)
- 2 x Stainless Steel Clamp (4-1/16" to 5")
Installation Guide
- Safety First: Ensure the engine is completely cool and turned off before beginning work.
- Locate Old Flapper: Identify the existing external exhaust flapper valve on the exhaust pipe near the transom.
- Remove Clamp: Loosen and remove the clamp that secures the old flapper valve.
- Remove Old Flapper: Slide the old, worn flapper off the pipe. Thoroughly clean any dirt or residue from the pipe surface.
- Position New Flapper: Slide the new flapper valve onto the pipe. Ensure it is oriented correctly to let exhaust out and prevent water from getting in.
- Secure New Flapper: Use the provided stainless steel clamp to secure the new valve. Tighten it firmly but do not overtighten, which could damage the rubber.
- Check Operation: Manually check that the flapper moves freely and can form a seal when closed.
- Final Test: Briefly start the engine to check for any exhaust leaks around the new connection.
Troubleshooting & FAQ
Q: How do I know if this flapper valve will fit my engine?
A: This 4" flapper valve is designed for MerCruiser stern drive models from 1994 and newer and also fits some OMC/Volvo applications with 4" exhaust systems. The most reliable way to confirm fitment is to measure your exhaust pipe's outer diameter and cross-reference your existing part number with those listed (e.g., 12644A1, 9-44001).
Q: What are the signs that my exhaust flapper needs replacement?
A: Common signs of a failing exhaust flapper include a persistent rattling or clanking sound from the stern at idle, visible cracks or damage to the rubber, or finding pieces of the old flapper in the exhaust. A damaged flapper can allow water to enter the engine, leading to serious damage.
Q: Is this an internal or external flapper?
A: This is an external flapper valve that is installed on the outside of the exhaust Y-pipe and secured with a clamp.
Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.
Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.
Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.
Important Notes
- Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
- This product is an aftermarket replacement part and is not an OEM component.
- Professional installation is recommended to ensure safety and optimal performance.
Why Choose JLM MARINE?
- Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
- Fast Global Shipping: Free delivery worldwide in 5–15 days.
- Direct from Manufacturer: Competitive pricing without compromising quality.
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy