Water Pump Impeller Kit – Fits Mercury/Mariner 3.5-9.8 HP Outboards (Replaces 47-89980T1, 89980Q1)

Water Pump Impeller Kit – Fits Mercury/Mariner 3.5-9.8 HP Outboards (Replaces 47-89980T1, 89980Q1)

This water pump impeller kit is designed for specific Mercury/Mariner 1-cylinder, 2-stroke outboards from 3.5 HP to 9.8 HP manufactured between 1979 and 1986. It is critical to ensure your engine's impeller has a 0.438" inner diameter for this kit to fit.

This kit serves as a direct replacement for several OEM and aftermarket part numbers, ensuring a precise fit and restoring your engine's cooling performance. It is engineered to meet or exceed original equipment specifications.

• Engineered as a direct replacement for a straightforward installation.
• Kit includes the impeller, wear plate, O-rings, and sleeve for a complete service.
• The impeller is made from a durable, high-performance neoprene/rubber compound for longevity.

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 Sleeve (700-12963)
• 1 x Impeller (700-89800)
• 1 x Wear Plate (700-12560)
• 1 x O-Ring (700-81230)
• 1 x O-Ring (700-81090)
• 1 x Seal (700-85651)

Installation Guide

1. Safety First: Disconnect the battery and shift the outboard into the neutral position.
2. Remove Lower Unit: Locate and unbolt the lower unit (gearcase) from the main engine housing. Keep track of all bolts.
3. Access Water Pump: With the lower unit removed, find the water pump housing, which sits on top of the gearcase.
4. Disassemble Housing: Remove the bolts securing the water pump cover to expose the impeller.
5. Remove Old Impeller: Note the rotational direction of the old impeller blades before carefully sliding it off the driveshaft. A flathead screwdriver may be needed to gently pry it up.
6. Clean Surfaces: Thoroughly clean any old gasket material, sealant, or debris from the housing, cover, and wear plate.
7. Install New Components: Place the new wear plate and gaskets into the housing as provided in the kit.
8. Lubricate: Apply a light coat of marine-grade grease to the interior of the pump housing and the new impeller.
9. Install New Impeller: Slide the new impeller onto the driveshaft. While pushing down, turn the driveshaft clockwise to bend the vanes into the correct orientation.
10. Reassemble Pump: Reinstall the water pump housing cover and tighten the bolts to the manufacturer's specified torque.
11. Reinstall Lower Unit: Carefully guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube are correctly aligned. Secure it with the mounting bolts.
12. Test Operation: Reconnect the battery and start the engine using a water supply (flushing muffs or a test tank) to confirm a steady water stream from the telltale outlet.

Troubleshooting & FAQ

How do I confirm this fits my engine?
This kit fits specific Mercury/Mariner 1-cylinder, 2-stroke outboards (3.5 HP to 9.8 HP) made from 1979-1986. The most crucial check is the impeller inner diameter (ID), which must be 0.438 inches. Please measure your existing impeller or driveshaft and cross-reference your engine model with our compatibility table before ordering.

What are the signs of a failing water pump impeller?
Common symptoms include a weak or inconsistent water stream from the "telltale" outlet, engine overheating alarms, or a melted water pump housing. Upon inspection, a worn impeller may appear cracked, brittle, torn, or have stiff blades.

How often should I replace the impeller?
For preventative maintenance, we recommend inspecting the impeller annually and replacing it every 1-2 years. Replacement frequency depends on usage hours, operating conditions (saltwater vs. freshwater), and storage practices.

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, especially the 0.438" impeller ID, 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.