Water Pump Impeller – Fits Mercury/Mariner 3.5–9.8 HP (Replaces 47-89980, 47-68988)

Water Pump Impeller – Fits Mercury/Mariner 3.5–9.8 HP (Replaces 47-89980, 47-68988)

This water pump impeller is designed for a precise fit on a range of vintage Mercury and Mariner 2-stroke outboard motors from 3.5 HP to 9.8 HP, generally covering models from 1966 to 1986. It serves as a direct replacement for your original, worn-out impeller to restore cooling system performance.

Engineered to meet or exceed original equipment specifications, this impeller replaces multiple part numbers, ensuring wide compatibility with the specified engine models. Please verify your driveshaft diameter before ordering, as some models used different sizes.

• Installation Method: Direct OEM-style replacement.
• Included Components: Contains one water pump impeller.
• Critical Fitment Note: Your engine's driveshaft diameter must be 0.438 inches (11.0 mm) for this part to fit.

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 x Water Pump Impeller (47-89980)

Installation Guide

1. Disconnect the negative battery cable to prevent accidental starting.
2. Place a drain pan under the lower unit and remove the gearcase drain/fill screws to empty the gear lube.
3. Remove the mounting bolts that secure the lower unit (gearcase) to the outboard's upper housing.
4. Carefully separate the lower unit from the driveshaft housing. The driveshaft will come out with it.
5. Locate the water pump assembly on top of the gearcase. Remove the bolts holding the water pump cover.
6. Slide the plastic cover up and off the driveshaft. Note the orientation of the old impeller's blades.
7. Remove the old impeller, woodruff key, and any gaskets or wear plates.
8. Clean all mating surfaces of old gasket material and debris.
9. Install the new gaskets and plates as required. Slide the new impeller onto the driveshaft while turning the shaft clockwise to bend the vanes in the correct direction.
10. Reinstall the water pump housing and tighten the bolts to the manufacturer's specified torque.
11. Apply a light coat of marine grease to the driveshaft splines and reinstall the lower unit.
12. Refill the gearcase with fresh lubricant, reconnect the battery, and test the engine's cooling system in water.

Troubleshooting & FAQ

How do I confirm this fits my engine?
First, check the compatibility table on this page to ensure your model and serial number range are listed. Crucially, you must also verify your engine's driveshaft diameter. Mercury sometimes used different shafts within the same model range. This impeller only fits a driveshaft with a diameter of 0.438 inches (11.0 mm).

Will this fit a 5 HP Mercury outboard?
No, this part will not fit a 5 HP Mercury engine. Those models typically use a different impeller, part number 47-16154-3.

How often should I replace the water pump impeller?
For preventative maintenance, it is recommended to replace the impeller every 1-2 seasons or every 100-200 hours of use, whichever comes first. You should also replace it immediately if you notice a weak water stream from the tell-tale port or if the engine begins to overheat.

OEM vs. Aftermarket?
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.

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

What is your warranty and return policy?
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.