Water Pump Impeller – Fits Mercury/Mariner 8/9.9 HP 4-Stroke, 6/8/9.8 HP 2-Stroke (Replaces 47-8037481)

Water Pump Impeller – Fits Mercury/Mariner 8/9.9 HP 4-Stroke, 6/8/9.8 HP 2-Stroke (Replaces 47-8037481)

This water pump impeller is a direct replacement for various Mercury, Mariner, Tohatsu, Nissan, and Parsun outboard engines. It is designed to fit 8–9.9 HP 4-Stroke models (2005 and newer) and 6–9.8 HP 2-Stroke models from Mercury/Mariner, as well as a range of 2-stroke and 4-stroke Tohatsu, Nissan, and Parsun engines.

This component is a direct replacement for Mercury part numbers 47-8037481, 8M0214945, and Tohatsu part number 3B2-65021-1. Please verify compatibility with your engine's model and serial number before ordering.

• Constructed from durable neoprene rubber with a plastic hub for reliable performance.
• Includes the water pump impeller and a square drive key for installation.
• Engineered to meet or exceed OEM specifications for cooling efficiency.

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.

Mercury/Mariner

Tohatsu/Nissan

Parsun

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (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.

Installation Guide

1. Disconnect the battery and shift the outboard into the neutral position.
2. Remove the lower unit (gearcase) from the outboard's driveshaft housing. This typically involves removing several bolts.
3. Locate and unbolt the water pump housing, which is usually found on top of the gearcase.
4. Carefully lift the housing to expose the old impeller. Note the orientation of the impeller blades.
5. Remove the old impeller from the driveshaft. You may also need to remove the old drive key.
6. Clean any debris or corrosion from the housing interior and wear plate.
7. Install the new square drive key into the slot on the driveshaft.
8. Slide the new impeller onto the driveshaft, aligning the keyway with the drive key.
9. While pushing down, turn the driveshaft clockwise to bend the impeller blades into the correct rotational direction.
10. Reinstall the water pump housing and tighten the bolts to the manufacturer's specified torque.
11. Reattach the lower unit to the outboard, ensuring the driveshaft, shift shaft, and water tube are correctly aligned.
12. Securely tighten all lower unit mounting bolts and reconnect the battery before testing.

Troubleshooting & FAQ

Q: How do I confirm this impeller fits my engine?
A: The best way to ensure fitment is to match your engine's model and year against the compatibility tables above. Cross-referencing your old part number with the numbers listed (e.g., Mercury 47-8037481, Tohatsu 3B2-65021-1) is also highly recommended. Use the provided guides for Mercury to help find your serial number.

Q: What are the signs of a worn or failing impeller?
A: Common symptoms include a weak or non-existent water stream from the "telltale" outlet, engine overheating alarms, and a decrease in overall cooling performance. A visual inspection may reveal cracked, brittle, or broken blades on the old impeller.

Q: How often should I replace my water pump impeller?
A: As a general maintenance rule, it is recommended to inspect your impeller annually and replace it every 1-2 years, or after every 100-200 hours of use. Replacement intervals can vary based on operating conditions, especially in saltwater or sandy/silty environments.

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.