Water Pump Impeller Kit for Johnson/Evinrude 4, 4.5, 5, 6 and 8 HP Outboards – Replaces 396644, 389844 and 765603
Water Pump Impeller Kit for Johnson/Evinrude 4, 4.5, 5, 6 and 8 HP Outboards – Replaces 396644, 389844 and 765603 is backordered and will ship as soon as it is back in stock.
Worry-free returns
Worry-free returns
Shop with confidence. If you’re not completely satisfied, eligible items may be returned within the return window, provided they are unused and in original packaging.
If the return is due to our error or a defective item, we’ll make it right.
Please contact us before returning any item.
Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Water Pump Impeller Kit for Johnson/Evinrude 4, 4.5, 5, 6 and 8 HP ...
Water Pump Impeller Kit for Johnson/Evinrude 4, 4.5, 5, 6 and 8 HP Outboards – Replaces 396644, 389844 and 765603 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket water pump impeller repair kit is designed for selected Johnson and Evinrude outboard motors. Listed applications include specific 2-stroke models rated at 4 HP (1986–1992), 4.5 HP (1980–1997), 5 HP (1980–1983 and 1996–1998), 6 HP (1984–2005), and 8 HP (1980–2005). It also covers selected 4-stroke models rated at 5 HP (1999–2001) and 6 HP (1999–2004).
The kit is listed as a replacement for Johnson/Evinrude part numbers 396644, 389844, and 765603, as well as Sierra reference 18-4529. Always compare the engine model, year, original part number, and existing water-pump components before ordering.
- Aftermarket replacement for the listed water-pump applications.
- Includes the impeller, housing components, gaskets, grommets, key, screws, and related service parts listed below.
- Helps restore water circulation and cooling-system performance when the original pump components are worn.
Part Number Matrix
Use these references to compare the replacement with the part number from your original water-pump assembly or service documentation.
| Brand | Part Number |
|---|---|
| Johnson/Evinrude | 396644 |
| Johnson/Evinrude | 389844 |
| Johnson/Evinrude | 765603 |
| Sierra | 18-4529 |
Engine & Model Compatibility
Confirm the engine brand, model, horsepower, stroke type, and year before purchase. The compatibility ranges below are application guides; model and serial-number details should also be checked against the engine identification plate and service information.
| Brand | Model | Rated HP | Stroke | Years | Reference 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 Specifications
- Product Type
- Water pump impeller repair kit
- Installation
- Aftermarket replacement for the listed applications
- Housing Material
- Plastic
- Housing Color
- Black
- Weight
- Approximately 0.17 kg (6.2 oz)
What’s in the Box
- 1 × Drive key — 331130, 18-3026
- 1 × Grommet — 321129, 18-1827
- 1 × Grommet — 302497, 18-3329
- 1 × Screw set — 324430, 18-4277
- 1 × Impeller housing plate — 324640, 18-4578
- 1 × Impeller housing cup — 324641, 18-4551
- 1 × Impeller housing gasket — 325040, 18-99156
- 1 × Impeller assembly — 389576, 18-3091
- 1 × O-ring — 303191, 18-7413
- 1 × Gasket — 311598
Installation Notes
- Disconnect the battery and follow the engine manufacturer’s safety procedure before beginning service.
- Remove the lower-unit fasteners and carefully separate the lower unit from the upper housing.
- Locate and remove the water-pump housing bolts and the existing pump components.
- Clean the mounting surfaces and remove old gasket material, debris, and corrosion.
- Install the gasket, wear plate, impeller with drive key, and housing cup. Confirm that the impeller is seated correctly and that the vanes are oriented in the proper direction for installation.
- Apply suitable marine grease or assembly lubricant where recommended by the engine manufacturer, including applicable housing surfaces and bolt threads.
- Secure the housing assembly with the supplied screws and tighten them according to the manufacturer’s specified torque.
- Reinstall the lower unit, making sure the driveshaft and water tube are correctly aligned.
- Test the engine in an appropriate water supply and confirm water flow from the tell-tale outlet before normal operation.
Troubleshooting & FAQ
How do I know if this kit fits my specific model?
Match your engine’s brand, model, horsepower, stroke type, and year with the compatibility table. Also compare the part number from the existing water-pump assembly or service manual with the listed references: 396644, 389844, 765603, and Sierra 18-4529. If the model or component details differ, verify fitment before ordering.
What are the signs of a failing water-pump impeller?
Common symptoms include weak or absent water flow from the tell-tale outlet, overheating, and visible damage such as cracked, brittle, distorted, or missing impeller vanes. A worn housing, plate, or gasket can also reduce pump performance.
How often should the water-pump impeller be replaced?
Inspect the impeller during routine maintenance and replace it when the vanes show wear, hardening, cracking, deformation, or damage. Replacement intervals depend on operating hours, storage conditions, and whether the engine is used in saltwater, sandy water, or other debris-containing environments.
Is this a complete kit, or do I need other parts?
This listing includes the impeller, housing components, plate, gaskets, grommets, drive key, screws, and other parts listed in the package-contents section. Confirm the supplied components against your engine’s service requirements before starting the repair, because additional parts may be required if other lower-unit or cooling-system components are damaged.
Is the included housing necessary to replace?
The housing should be inspected whenever the impeller is replaced. Scoring, warping, excessive wear, heat damage, or debris damage can prevent proper sealing and reduce water-pump performance. Replacing worn housing components with the impeller helps provide a proper repair.
What is the difference between an OEM part and this aftermarket replacement?
This listing is for an aftermarket replacement rather than an original-equipment part. It is intended for the applications and reference numbers listed on this page. Compare the original component and confirm the engine details before installation.
What are the shipping speed and cost?
Standard shipping is offered at no additional charge where available. Typical transit is 5–15 days, while expedited options and delivery estimates are shown at checkout based on the destination.
What is the warranty and return policy?
Returns are subject to the applicable store policy and normally require the item to be unused and in its original condition. Contact customer support with your order details if you receive a damaged or incorrect item or if a manufacturing issue occurs.
Safety & Important Information
- Verify the engine model, year, horsepower, stroke type, and original part number before purchase.
- Compare the replacement components with the original water-pump assembly before installation. Do not proceed if the parts differ in a way that affects fit or operation.
- This is an aftermarket replacement component and is not manufactured as an original-equipment manufacturer part.
- Follow the engine manufacturer’s service procedures and torque specifications. Professional installation is recommended when lower-unit service experience is limited.
About Sea Sierra
- Pro-Grade Standards — We supply marine replacement parts selected for dependable fit and service performance.
- Fast Global Fulfillment — We offer standard delivery to most regions, with estimated transit times shown during checkout.
- Manufacturer-Direct Value — We work with manufacturing partners to provide practical replacement solutions for marine maintenance and repair.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
