Water Pump Impeller Kit – Fits Johnson/Evinrude 4-8 HP Outboards (Replaces 396644, 0396644, 18-4529)

Water Pump Impeller Kit – Fits Johnson/Evinrude 4-8 HP Outboards

This water pump impeller service kit is designed for Johnson/Evinrude 4 HP, 4.5 HP, 5 HP, 6 HP, and 8 HP 2-stroke outboard models. It provides the necessary components for repairing and maintaining your engine's cooling system.

This kit is a direct replacement for Johnson/Evinrude part numbers 396644 / 0396644, Sierra 18-4529, and GLM 12065.

• Includes a new impeller, wear plate, gaskets, and mounting hardware for a complete overhaul.
• Engineered for a direct fit, reusing the original plastic pump housing.
• Restores cooling system performance to prevent engine overheating.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Johnson/Evinrude owners, here’s a guide to help you identify your engine’s serial/model: Johnson/Evinrude Serial Number Guide.

Technical Specifications

Package Contents

• 1 x Impeller Assembly (389576, 18-3091)
• 1 x Drive Key (331130, 18-3026)
• 1 x Grommet (321129, 18-1827)
• 1 x Grommet (302497, 18-3329)
• 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 O-Ring (303191, 18-7413)
• Screws (324430, 18-4277)
• Note: This kit is designed to reuse your existing plastic water pump housing and does not include a new housing.

Installation Guide

1. Safety First: Disconnect the battery and spark plug wires before starting work.
2. Access Lower Unit: Drain the gearcase oil and remove the lower unit (gearcase) from the outboard's driveshaft housing.
3. Remove Pump Housing: Locate the water pump assembly on top of the gearcase. Unbolt and remove the pump housing to expose the impeller.
4. Inspect and Clean: Remove the old impeller, key, gaskets, and wear plate. Clean all mating surfaces thoroughly, removing any old gasket material or corrosion.
5. Install New Components: Place the new gaskets, wear plate, and insert cup. Slide the new impeller onto the driveshaft, ensuring the keyway is aligned and the blades are oriented correctly (typically clockwise).
6. Reassemble Pump: Apply a light coat of marine grease or soap-water solution to the inside of the housing and carefully slide it down over the impeller, turning the driveshaft to seat the blades.
7. Torque and Refill: Secure the housing with the new screws, torquing them to the manufacturer's specification. Reinstall the lower unit and refill the gearcase with fresh oil.
8. Test Operation: Reconnect the battery and start the engine in water. Immediately check for a steady stream of water from the "tell-tale" outlet, confirming proper pump operation.

Troubleshooting & FAQ

How do I know if this kit will fit my engine?

Verify your engine's model, HP, and year against the "Compatible Engine Models" table. You can also confirm by matching your existing part number to the cross-reference list, which includes Johnson/Evinrude 396644 / 0396644, Sierra 18-4529, and GLM 12065.

Does this kit include the plastic water pump housing?

No, this service kit is designed to reuse your existing plastic housing. It includes the internal wear components like the impeller, cup, plate, and gaskets needed for a standard service.

What are the signs that my water pump impeller is failing?

The most common signs are the engine overheating at idle or low speeds, or a weak or intermittent water stream coming from the "tell-tale" cooling outlet. Upon inspection, a worn impeller will have cracked, brittle, or permanently curved vanes.

How often should a water pump impeller be replaced?

For preventative maintenance, it is recommended to inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of engine use. Replacement intervals should be shorter in saltwater or silty water environments.

OEM vs. Aftermarket?

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.

How fast do you ship and how much does it cost?

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.

What is your warranty and return policy?

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.