4" Exhaust Flapper Valve for MerCruiser Stern Drives 1994 and Newer — Replaces 12644A1 and 12644Q01
4" Exhaust Flapper Valve for MerCruiser Stern Drives 1994 and Newer — Replaces 12644A1 and 12644Q01 is backordered and will ship as soon as it is back in stock.
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4" Exhaust Flapper Valve for MerCruiser Stern Drives 1994 and ...
4" Exhaust Flapper Valve for MerCruiser Stern Drives 1994 and Newer — Replaces 12644A1 and 12644Q01 is backordered and will ship as soon as it is back in stock.
Product Details
This 4-inch exhaust flapper valve is designed for compatible MerCruiser stern-drive exhaust systems from 1994 and newer. Installed at the exhaust outlet, it helps reduce the risk of water entering the engine through the exhaust system while allowing exhaust gases to exit normally.
The valve is made from compounded EPDM rubber with a UV stabilizer for resistance to weather and marine operating conditions. It is an aftermarket replacement for MerCruiser references 12644A1 and 12644Q01.
- For compatible 4-inch exhaust outlets.
- External exhaust-outlet installation.
- Weather-resistant EPDM rubber construction with UV stabilizer.
- Sold as one exhaust flapper valve. Clamps and additional valves are not included unless specifically shown in the order options or product photos.
Part Number References
Use the following numbers as cross-reference information and verify the dimensions and configuration of your existing part before ordering.
| Brand or Source | Reference Number |
|---|---|
| MerCruiser | 12644A1 |
| MerCruiser | 12644Q01 |
| Mallory | 9-44001 |
| GLM | 89250 |
| Sierra | 18-4457 |
Engine and Model Compatibility
This valve is intended for compatible MerCruiser stern-drive applications using a 4-inch exhaust system and corresponding exhaust flapper configuration. Model coverage can vary by exhaust design, so confirm the original part number, outlet diameter, and mounting arrangement before purchase.
| Brand | Application | Years | Exhaust Size | OEM Reference | Notes |
|---|---|---|---|---|---|
| MerCruiser | Compatible stern-drive models | 1994 and newer | 4 inches | 12644A1, 12644Q01 | Verify the original valve and exhaust outlet dimensions before installation. |
Technical Specifications
- Product Type
- Exhaust flapper valve
- Installation
- External exhaust-outlet installation
- Nominal Exhaust Size
- 4 inches (101.6 mm)
- Material
- EPDM rubber with UV stabilizer
- Clamp Requirement
- Uses an appropriate external clamp; clamp is not included with this single-valve product
- Color
- Black
- Approximate Dimensions
- 7.25 × 6.75 × 2 inches (184.15 × 171.45 × 50.8 mm)
- Approximate Weight
- 0.5 lb (0.227 kg)
What's in the Box
- 1 × 4-inch exhaust flapper valve
Note: This listing is for a single valve. Stainless-steel clamps and a second valve are not included.
Installation Notes
- Ensure the engine is switched off and completely cool, and secure the vessel before beginning work.
- Locate the applicable exhaust outlet on the transom or stern-drive exhaust assembly.
- Loosen and remove the existing clamp, then remove the old flapper valve.
- Clean the outside of the exhaust outlet and inspect it for corrosion, damage, or deformation.
- Position the replacement flapper over the exhaust outlet in the same orientation as the original part.
- Install a suitable clamp over the valve and place it in the correct mounting position.
- Tighten the clamp securely without overtightening or damaging the rubber.
- If the vessel has more than one exhaust outlet, inspect and service each outlet separately using the correct replacement parts.
Troubleshooting and FAQ
How do I confirm that this valve fits my MerCruiser application?
Confirm that your stern-drive exhaust system uses a 4-inch outlet and compare the original valve with the listed dimensions and reference numbers, 12644A1 or 12644Q01. Exhaust configurations can vary, so verify the mounting arrangement before ordering.
What are the signs of a failing exhaust flapper?
Common signs include cracks, stiffness, brittleness, distortion, or a loose or rattling flapper. A damaged or missing flapper may increase the risk of water entering through the exhaust system. Inspect the valve during routine or seasonal maintenance.
How often should an exhaust flapper be replaced?
Inspect it at least annually and whenever the boat is serviced. Replacement timing depends on use and exposure to saltwater, heat, and weather. Replace the valve if the rubber is cracked, hardened, torn, or no longer moves freely.
Can I install this valve myself?
Installation is generally a straightforward mechanical repair for an experienced boat owner, but the engine must be cool and the vessel must be secured. If the exhaust system is difficult to access or you are uncertain about the correct orientation, use a qualified marine technician.
Is this a single flapper or a pair?
This product is sold as one exhaust flapper valve. It is not a two-valve kit, and clamps are not included.
Is this an OEM part?
This is an aftermarket replacement valve, not a MerCruiser-branded OEM component. It is listed as a replacement for the stated MerCruiser reference numbers.
Safety and Important Information
- Verify the original part number, exhaust diameter, dimensions, and mounting arrangement before ordering.
- Do not operate the engine with a damaged, improperly installed, or missing exhaust flapper.
- Do not reuse a damaged or corroded clamp; use a suitable replacement clamp when required.
- Professional installation is recommended if you are unsure about fitment or installation.
About Sea Sierra
- Marine Replacement Parts — Practical replacement components for routine boat maintenance and repair.
- Application-Focused Information — Check dimensions, reference numbers, and installation requirements before ordering.
- Support for Marine Maintenance — Choose the correct component for your exhaust system and service conditions.
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