Water Pump Impeller – Fits Tohatsu/Nissan 9.9–20 HP & Mercury 8–20 HP (Replaces 334-65021-0, 47-803748)

Water Pump Impeller – Fits Tohatsu/Nissan 9.9–20 HP & Mercury 8–20 HP (Replaces 334-65021-0, 47-803748)

This water pump impeller is a direct replacement for a wide range of outboard motors, including Tohatsu/Nissan 9.9–20 HP (2-Stroke & 4-Stroke), Mercury/Mariner 8–20 HP (4-Stroke), and select Honda 7.5–10 HP models.

It directly replaces OEM part numbers: Tohatsu 334-65021-0 / 334650210 / 334650210M, Mercury 47-803748 / 8M0214944, Honda 19210-935-003, Evinrude 5040046, and Sierra 18-8921.

• Installation: Direct OEM replacement for a hassle-free fit.
• Connection: Mounts on a key-driven shaft.
• Included Parts: Includes one salt water-resistant rubber impeller.

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 Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

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 Serial Number Guide.

Confirm your engine model/year in the table below.

Tohatsu/Nissan Models

Mercury/Mariner Models

Honda Models

Evinrude Models

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (334-65021-0/47-803748)

Installation Guide

1. Safety First: Disconnect the battery and remove the spark plug wires before beginning.
2. Access the Lower Unit: Shift the outboard into neutral and remove the bolts securing the lower unit (gearcase) to the engine leg.
3. Lower the Unit: Carefully separate the lower unit from the driveshaft housing to expose the water pump assembly.
4. Disassemble Pump Housing: Remove the bolts holding the water pump cover in place. Note the orientation of all parts.
5. Remove Old Impeller: Take note of the direction the impeller blades are bent. Remove the old impeller from the driveshaft.
6. Clean & Inspect: Thoroughly clean the inside of the pump housing and wear plate. Check for scoring, warping, or corrosion.
7. Install New Impeller: Lightly lubricate the new impeller and housing interior with a marine-safe lubricant. Slide the new impeller onto the shaft, twisting it in the direction of engine rotation to correctly orient the blades.
8. Reassemble: Reinstall the water pump housing, ensuring all seals and gaskets are correctly positioned. Torque bolts to manufacturer specifications.
9. Reattach Lower Unit: Guide the lower unit back into place, aligning the driveshaft, shift shaft, and water tube. Secure it with the bolts.
10. Test Operation: Reconnect the battery and start the engine in water. Immediately check for a steady stream of water from the "tell-tale" outlet.

Troubleshooting & FAQ

Q: How do I confirm this impeller fits my specific engine model?

A: The best way to ensure compatibility is to match your engine's original part number with the numbers listed in our "Part Number Cross-Reference" table. Additionally, check your model, horsepower, and stroke against our "Compatible Engine Models" tables.

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

A: The most common indicators of a worn or damaged impeller are an overheating engine at idle or low speeds, and a weak or nonexistent water stream from the tell-tale port on the engine cowling.

Q: How often should I replace my water pump impeller?

A: As a general rule, we recommend replacing the impeller every 1-2 years or every 100-200 hours of operation, whichever comes first. This interval can vary based on usage conditions (e.g., saltwater vs. freshwater) and your engine manufacturer's specific guidelines.

Q: OEM vs. Aftermarket?

A: 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.

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

A: 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.

Q: What is your warranty and return policy?

A: 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.