Water Pump Impeller – Fits Mercury/Tohatsu/Nissan 8/9.9HP 4-Stroke, 6/8/9.8HP 2-Stroke

Water Pump Impeller – Fits Mercury/Tohatsu/Nissan 8/9.9HP 4-Stroke, 6/8/9.8HP 2-Stroke (Replaces 47-8037481, 3B2-65021-1)

This water pump impeller is engineered to fit a range of Mercury, Tohatsu, Nissan, and Parsun outboard motors. It serves as a crucial component for maintaining proper engine cooling by ensuring consistent water flow through the lower unit's water pump assembly.

Designed as a direct replacement for OEM parts, this impeller meets or exceeds original equipment specifications for fit, form, and function. It provides a reliable and cost-effective solution for routine maintenance or repair.

• Material: Durable neoprene rubber for longevity and performance.
• Installation: Requires a square key for mounting on the driveshaft.
• Package Includes: 1 x Water Pump Impeller and 1 x Square Key.

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.

For Tohatsu, Nissan, and Parsun models, confirm your engine model/year in the tables below.

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (Replaces 47-8037481 / 3B2-65021-1)
• 1 x Square Drive Key (for driveshaft mounting)
• Note: Package contents may vary between suppliers; some kits may only include the impeller without the key. Please verify contents upon receipt.

Explosion Diagram

Installation Guide

1. Safety First: Disconnect the battery and ensure the outboard is shifted into neutral.
2. Detach Lower Unit: Remove the bolts securing the lower unit (gearcase) to the upper leg of the outboard and carefully detach it.
3. Access Pump: Locate the water pump housing on top of the lower unit and remove its mounting bolts.
4. Remove Old Impeller: Lift the housing off. Note the rotational direction of the old impeller blades before removing the impeller and the drive key from the shaft.
5. Clean and Inspect: Thoroughly clean the inside of the pump housing and wear plate. Inspect them for scoring, warping, or corrosion and replace if necessary.
6. Install New Impeller: Place the new square key into the slot on the driveshaft. Slide the new impeller onto the shaft.
7. Seat Impeller: While pushing down on the pump housing, turn the driveshaft clockwise to correctly flex the impeller blades and seat them inside the housing.
8. Reassemble Pump: Reinstall the bolts for the water pump housing and tighten them to the manufacturer's recommended torque.
9. Reattach Lower Unit: Carefully guide the lower unit back into position, ensuring the driveshaft, shift shaft, and water tube align correctly before securing the bolts.
10. Test Operation: Reconnect the battery. With the outboard in water or connected to a proper flush device, start the engine and check for a steady stream of water from the tell-tale outlet.

Troubleshooting & FAQ

Q: How do I confirm this impeller fits my engine?
A: The most reliable method is to match your engine's model and year against the 'Compatible Engine Models' table. For Mercury/Mariner owners, we highly recommend using your engine's serial number to verify fitment. A link to our Mercury Serial Number Guide is provided above to assist you.

Q: What are the signs of a failing water pump impeller?
A: Common symptoms include the engine overheating at idle or low speeds, a weak or intermittent water stream from the tell-tale outlet, or finding brittle, cracked, or melted pieces of the old impeller during inspection.

Q: How often should I replace my impeller?
A: As a critical preventative maintenance item, we recommend replacing the impeller every 1-2 years or every 100-200 hours of use. This interval should be shortened if the engine is frequently operated in sandy, silty water or saltwater.

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.