47-89980 47-68988 8M0032835 Water Pump Impeller for Mercury Mariner | JLM Marine

Water Pump Impeller for Mercury Mariner 3.5–9.8 HP Outboard Engines (47-89980, 47-68988, 8M0032835)

This aftermarket water pump impeller is engineered for Mercury and Mariner 1-cylinder, 2-stroke outboard engines ranging from 3.5 HP to 9.8 HP, manufactured between 1979 and 1985. It features a neoprene rubber construction with a brass hub and is designed for motors with a 0.438-inch shaft diameter.

Direct Replacements: This impeller replaces Mercury Marine OEM part numbers 47-89980, 47-68988, and 8M0032835, as well as Sierra Marine 18-3054, Mercury Mariner Marine 47-89980B, and Mercury Mariner Marine 47-89980T-1.

• Includes outboard rubber impeller with key/pin
• Compatible with engines using 0.438-inch internal diameter shaft only (not for 5 HP models with 0.456-inch shaft)
• Installation requires lubrication with silicone grease, glycerine, or dish soap (not included)

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.

Technical Specifications

Package Contents

• 1 × Outboard Rubber Impeller with Key/Pin

CRITICAL NOTE: This impeller is designed for Mercury Mariner outboards with a 0.438-inch internal diameter shaft. If your impeller has an inside diameter of 0.456 inch, this is NOT the correct impeller for you. This impeller will NOT fit 5 HP Mercury Mariner engines. For 0.456-inch internal diameter impellers, please see part number 47-89981.

Installation Guide

1. Disconnect the spark plug wire and ensure the engine is off and cool.
2. Remove the lower unit from the outboard motor following your service manual instructions.
3. Disassemble the water pump housing by removing the retaining bolts and carefully separating the housing components.
4. Remove the old impeller from the shaft; inspect the housing and plate for wear or damage.
5. Clean all surfaces thoroughly, removing old gasket material and debris.
6. Lubricate the new impeller generously with silicone grease, glycerine, or dish soap (do not use petroleum-based products).
7. Install the key/pin into the impeller slot, ensuring it is properly seated.
8. Carefully slide the impeller onto the drive shaft, aligning the key with the shaft keyway. Rotate the blades in the correct direction of rotation during installation.
9. Reassemble the water pump housing with new gaskets, ensuring proper alignment and torque specifications.
10. Reinstall the lower unit onto the outboard motor, reconnecting all linkages and fasteners.
11. Fill the lower unit with the correct gear oil and check for leaks.
12. Reconnect the spark plug wire, start the engine in a test tank or on the water, and confirm strong water flow from the tell-tale indicator.

Troubleshooting & FAQ

Q: How do I confirm this impeller fits my Mercury or Mariner engine?
A: Verify that your engine is listed in the Compatible Engine Models table and that your drive shaft has an internal diameter of 0.438 inch. Measure the center hole of your old impeller to confirm. If your shaft diameter is 0.456 inch, you need part number 47-89981 instead.

Q: What are the signs that my water pump impeller needs replacement?
A: Common symptoms include reduced or no water flow from the tell-tale, engine overheating, steam from the powerhead, or visible cracks and missing vanes on the old impeller. Replace the impeller annually or every 200–300 operating hours as preventive maintenance.

Q: Can I use petroleum-based grease when installing the impeller?
A: No. Petroleum-based products can damage neoprene rubber. Always use silicone grease, glycerine, or dish soap for lubrication during installation.

Q: Will this impeller fit my 5 HP Mercury Mariner outboard?
A: No. Most 5 HP Mercury Mariner engines require an impeller with a 0.456-inch internal diameter (part number 47-89981). This impeller is designed for 0.438-inch shafts only.

Q: How often should I replace the water pump impeller?
A: We recommend annual replacement or every 200–300 hours of operation, whichever comes first. If the engine has been stored dry or run in sandy/silty water, inspect and replace more frequently.

Q: Is this an OEM part or 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.