Water Pump Impeller Kit – Fits Johnson/Evinrude 4, 4.5, 5, 6, 8 HP (Replaces 396644, 389844)
Water Pump Impeller Kit – Fits Johnson/Evinrude 4, 4.5, 5, 6, 8 HP (Replaces 396644, 389844) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Water Pump Impeller Kit – Fits Johnson/Evinrude 4, 4.5, 5, 6, 8 HP ...
Product Details
This aftermarket Water Pump Impeller Kit is designed for a range of Johnson and Evinrude outboard motors. It fits specific 2-stroke models including 4 HP (1986–1992), 5 HP (1980–1983, 1996–1998), 6 HP (1984–2005), and 8 HP (1980–2005). It also covers 4-stroke models such as 5 HP (1999–2001) and 6 HP (1999–2004).
The kit serves as a direct replacement for Johnson/Evinrude part numbers 396644, 389844, and 765603, as well as Sierra 18-4529.
- Engineered for direct OEM-equivalent installation.
- Includes a new plastic housing, impeller, and all necessary seals and hardware.
- Restores cooling system performance to prevent overheating.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.
| Brand | Part Number |
|---|---|
| Johnson/Evinrude | 396644 |
| Johnson/Evinrude | 389844 |
| Johnson/Evinrude | 765603 |
| Sierra | 18-4529 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit is designed exclusively for the Johnson and Evinrude outboard models listed.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Johnson/Evinrude | Various | 4 | 2-Stroke | 1986–1992 | 396644, 389844 |
| Johnson/Evinrude | Various | 4.5 | 2-Stroke | 1980–1997 | 396644, 389844 |
| Johnson/Evinrude | Various | 5 | 2-Stroke | 1980–1983, 1996–1998 | 396644, 389844 |
| Johnson/Evinrude | Various | 5 | 4-Stroke | 1999–2001 | 396644, 389844 |
| Johnson/Evinrude | Various | 6 | 2-Stroke | 1984–2005 | 396644, 389844 |
| Johnson/Evinrude | Various | 6 | 4-Stroke | 1999–2004 | 396644, 389844 |
| Johnson/Evinrude | Various | 8 | 2-Stroke | 1980–2005 | 396644, 389844 |
Technical Specs
- Product Type
- Water Pump Impeller Repair Kit
- Installation
- Direct OEM Replacement
- Housing Material
- Plastic
- Housing Color
- Black
- Weight
- Approximately 0.17 kg (6.2 oz)
What’s in the Box
- 1 x Drive Key (331130, 18-3026)
- 1 x Grommet (321129, 18-1827)
- 1 x Grommet (302497, 18-3329)
- 1 x Screws (324430, 18-4277)
- 1 x Impeller Housing Plate (324640, 18-4578)
- 1 x Impeller Housing Cup (324641, 18-4551)
- 1 x Impeller Housing Gasket (325040, 18-99156)
- 1 x Impeller Assembly (389576, 18-3091)
- 1 x O-Ring (303191, 18-7413)
- 1 x Gasket (311598)
Installation Notes
- Disconnect the battery and remove the lower unit cowling.
- Unbolt and carefully separate the lower unit (gearcase) from the upper engine housing.
- Locate and remove the old water pump housing bolts and housing assembly.
- Clean the mounting surfaces, removing any old gasket material or corrosion.
- Install the new gasket, wear plate, impeller (with key), and housing cup. Ensure the impeller vanes are oriented correctly.
- Apply marine grease to the inside of the housing and bolt threads.
- Secure the new housing assembly with the provided screws, tightening to the manufacturer's specified torque.
- Reinstall the lower unit, ensuring the driveshaft and water tube align correctly.
- Reconnect the battery and test the engine in a water supply to verify proper water flow from the tell-tale outlet.
Troubleshooting & FAQ
How do I know if this kit fits my specific model?
The most reliable method is to match your engine's model, horsepower, and year to the compatibility table. Cross-referencing the OEM part number from your old unit or service manual with the numbers in our Part Number Matrix (396644, 389844) also ensures a correct fit.
What are the signs of a failing water pump impeller?
Common signs include a weak or non-existent stream of water from the "tell-tale" outlet, engine overheating alarms, and reduced engine performance. Visible damage to the old impeller, such as cracked, brittle, or missing vanes, confirms it needs replacement.
How often should the water pump impeller be replaced?
As a best practice for preventative maintenance, we recommend inspecting the impeller annually and replacing it every 1-2 years or every 100-200 hours of operation, depending on usage conditions (e.g., saltwater vs. freshwater).
Is this a complete kit, or do I need other parts?
This is a comprehensive repair kit containing the impeller, housing, plate, gaskets, grommets, and other essential components for a standard water pump service. No other parts are typically needed for this specific job.
Is the included housing a necessary replacement?
Yes, it is highly recommended. The plastic housing can warp or score from heat and debris over time, which compromises the seal against the new impeller and reduces water pressure. Replacing the housing and impeller together ensures a reliable, long-lasting repair.
What is the difference between OEM and this aftermarket part?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. It's manufactured in an ISO 9002 facility and batch-inspected for consistency, offering similar performance and fit at a better value.
What are your shipping speed and cost?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options will appear at checkout where available.
What is the warranty and return policy?
This part is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter any issues, please contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. See our policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part before purchase. If anything differs, even if your model is listed as compatible, do not proceed.
- This is an aftermarket replacement component, not an original equipment manufacturer (OEM) part.
- Professional installation is recommended for safety and optimal performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
- Fast Global Fulfillment — We offer free standard delivery to most regions, with an average transit time of 5–15 days.
- Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.
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