Water Pump Impeller Kit – Fits Mercury Mariner 2-Stroke 3.5–9.8 HP (Replaces 47-89980T1, 47-89980Q1)

Water Pump Impeller Kit – Fits Mercury Mariner 2-Stroke 3.5–9.8 HP (Replaces 47-89980T1, 47-89980Q1)

This water pump impeller service kit is designed for Mercury and Mariner 2-stroke outboard motors, including 3.5 HP, 3.6 HP, 3.9 HP, 4 HP, 4.5 HP, 6 HP, 7.5 HP, and 9.8 HP models manufactured between 1979 and 1986.

It serves as a direct replacement for multiple OEM and aftermarket part numbers, ensuring broad compatibility for engines requiring the smaller .438" impeller drive shaft. Please verify your engine specifications before ordering.

• Engineered for Mercury & Mariner 2-Stroke 3.5–9.8 HP outboards.
• Complete kit includes a neoprene impeller, SS316 wear plate, and installation hardware.
• Critical Note: Fits models with a 0.438-inch (11.1 mm) impeller inside diameter only.

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.

Important Fitment Note: Mercury used two different diameter drive shafts on outboard motors from 4 HP to 9.8 HP, often within the same serial number ranges. This impeller kit is designed exclusively for the smaller .438" (11.1 mm) impeller inside diameter. Please measure your existing impeller or driveshaft before ordering to ensure correct fitment.

Compatible Serial Number Ranges

Technical Specifications

Package Contents

• 1 x Impeller (47-89980/89980B)
• 1 x Wear Plate (46895)
• 1 x Key, Woodruff Impeller
• 1 x Sleeve, Water Guide Tube
• 3 x O-rings

Installation Guide

1. Shift the outboard into neutral and disconnect the battery.
2. Unbolt the lower unit (gearcase) from the outboard's main housing and disconnect the shift linkage.
3. Place the lower unit on a workbench and remove the bolts securing the water pump housing.
4. Lift the housing off, paying attention to the position of any O-rings or seals.
5. Slide the old impeller off the driveshaft, removing the Woodruff key that locks it in place.
6. Remove the old wear plate and any gaskets from the housing and base.
7. Clean all mating surfaces to remove corrosion or old gasket material.
8. Install the new wear plate and seals/O-rings included in the kit.
9. Insert the new Woodruff key into the driveshaft slot and guide the new impeller onto the shaft.
10. Apply downward pressure on the pump housing while rotating the driveshaft clockwise to seat the impeller blades correctly.
11. Secure the housing with its bolts, tightening them to the torque specs recommended by the manufacturer.
12. Re-install the lower unit, reconnect the shift linkage, and test the engine in water to confirm proper water flow.

Troubleshooting & FAQ

How do I confirm this kit fits my engine?
The most important step is to verify your engine's drive shaft diameter. This kit is only for models that use an impeller with a 0.438-inch (11.1 mm) inside diameter. Mercury used two different sizes in this HP range, so measuring your old part is the best way to guarantee fitment, even if your model and year are listed.

What are the signs of a failing water pump impeller?
Common signs include a weak or non-existent water stream from the "telltale" outlet, engine overheating alarms, and reduced engine performance. A visual inspection may also show cracked, brittle, or worn-down impeller blades.

How often should I replace the impeller?
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 frequency may vary depending on usage conditions (e.g., saltwater vs. freshwater).

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.