Water Pump Impeller with Key – Fits Yamaha 4HP 5HP 6HP (Replaces 6E0-44352-00, 18-3073, 500325, 9-45611)

Product Details

This Water Pump Impeller with Key is an aftermarket replacement designed for Yamaha 4HP, 5HP, and 6HP outboard motors. It fits both 2-stroke and 4-stroke engines manufactured from 1984 and up, ensuring reliable cooling system performance across a wide range of models including Yamaha F4, F6, and legacy 4HP/5HP units.

This impeller directly replaces Yamaha OEM part numbers 6E0-44352-00, 6E0-44352-01, and 6E0-44352-03, as well as aftermarket equivalents from Sierra Marine (18-3073), CEF Marine (500325), and Mallory Marine (9-45611).

• Includes impeller key/pin for secure installation
• 6-blade rubber design with precise OEM-spec dimensions
• Compatible with both 2-stroke and 4-stroke Yamaha outboards

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Technical Specs

Blades

6

Impeller Height

12.6 mm / 0.50 inch

Overall Diameter

40.0 mm / 1.57 inch

Hub Shaft Diameter

11.0 mm / 0.43 inch

Net Weight

0.35 oz

What's in the Box

• Outboard Rubber Impeller with Key / Pin

Installation Notes

1. Disconnect fuel line and remove engine cowling to access the lower unit.
2. Drain lower unit gear oil completely before disassembly.
3. Remove water pump housing bolts and carefully separate the housing from the lower unit.
4. Extract the old impeller using pliers or an impeller puller; note the rotation direction of the blades.
5. Clean the impeller chamber thoroughly, removing all debris, old gasket material, and corrosion.
6. Lubricate the new impeller blades with glycerin or waterproof grease—never petroleum-based products.
7. Insert the impeller key into the driveshaft slot, ensuring it is fully seated.
8. Install the new impeller by hand, bending blades in the correct rotational direction.
9. Replace the water pump gasket and O-rings; reattach the housing and torque bolts to manufacturer specifications.
10. Refill lower unit with appropriate gear oil and check for leaks.
11. Run the engine with water supply (muffs or tank) and verify steady water flow from the tell-tale port.

Troubleshooting & FAQ

How do I know when to replace my impeller?

Replace your impeller annually or every 200–300 operating hours, whichever comes first. Signs of failure include overheating, reduced or no water flow from the tell-tale, cracked or missing blades, and loss of engine power under load.

Will this impeller fit my specific Yamaha model?

This impeller is designed for Yamaha 4HP, 5HP, and 6HP outboards (both 2-stroke and 4-stroke) from 1984 onward. Cross-check your engine's model and serial number with the compatibility table above, and verify your current impeller part number matches one of the OEM references listed.

What's the correct way to install the impeller key?

The key must be inserted into the driveshaft slot before mounting the impeller. Ensure it sits flush and does not protrude beyond the shaft surface. The impeller hub will slide over the key, locking the impeller to the driveshaft for proper rotation.

Can I reuse the old gasket and O-rings?

No. Always replace gaskets and O-rings during impeller service to prevent leaks and ensure proper sealing. Reusing worn seals can lead to water intrusion, overheating, and premature impeller failure.

Why is my engine still overheating after impeller replacement?

Check for blockages in the cooling passages, a damaged water pump housing, incorrect impeller installation (blades bent the wrong direction), a faulty thermostat, or a clogged tell-tale port. Ensure the impeller key is correctly seated and the pump plate is properly aligned.

What lubricant should I use on the impeller?

Use glycerin, waterproof grease, or dishwashing liquid. Never use petroleum-based lubricants, as they will degrade the rubber and cause premature failure.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

• Verify images/specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.
• This is an aftermarket replacement, not an OEM component.
• Professional installation is recommended for safety and performance.

About Sea Sierra

• Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
• Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
• Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.