Heavy Duty Sea Water Pump Impeller Kit – Fits Mercury MerCruiser 4.5L, 6.2L MCM, MIE & TowSport Models (Replaces 47-8M0137221)

Heavy Duty Sea Water Pump Impeller Kit – Fits Mercury MerCruiser 4.5L, 6.2L MCM, MIE & TowSport Models

This heavy-duty sea water pump impeller kit is designed for specific Mercury MerCruiser engines. It is a direct-fit replacement component engineered to meet or exceed original equipment standards for performance and durability. This kit is intended for Mercury MerCruiser 4.5L engines (serial numbers 2A531163 and above) and 6.2L MCM (sterndrive), MIE (inboard), and TowSport engines (serial numbers 2A531197+, 2A530774+, and 2A531348+ respectively).

This component directly replaces Mercury/MerCruiser part numbers 47-8M0137221 and the superseded part number 98-8M0121940.

• Engineered with 8 blades and a profile 0.030" shorter than standard for specific applications.
• Installation method is a direct replacement of the original pump components.
• Complete kit includes the impeller and necessary wear plates for a full service.

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 Shorter Heavy Duty Impeller (8M0103389)
• 1 x Rear Wear Plate
• 1 x Overmolded Inner (Front) Wear Plate (8M0072979)
• 1 x Outer Wear Plate with Seal (8M0114788)

Installation Guide

1. Disconnect the negative battery cable and close the engine's seacock.
2. Locate the sea water pump housing and place a drain pan underneath.
3. Remove the bolts securing the pump cover and carefully detach the cover plate.
4. Note the rotational direction of the old impeller vanes before removal.
5. Use needle-nose pliers or an impeller puller tool to grip the hub and pull the old impeller straight out.
6. Remove the old front and rear wear plates.
7. Thoroughly clean the interior of the housing, removing any old gasket material or debris.
8. Install the new rear wear plate, inner wear plate, and outer wear plate with its seal.
9. Apply a light coat of water-resistant grease or dish soap to the inside of the housing and the new impeller.
10. Compress the blades of the new impeller and insert it into the housing, ensuring the blades are oriented in the correct rotational direction.
11. Reinstall the pump cover and tighten the bolts in a star pattern to the manufacturer's specified torque.
12. Open the seacock, reconnect the battery, start the engine, and immediately check for waterflow and leaks.

Troubleshooting & FAQ

How do I confirm this kit fits my engine?
This kit's compatibility is determined by your engine's serial number. Please verify that your serial number is at or above the ones listed for the 4.5L and 6.2L MerCruiser models. For example, it fits 4.5L engines with serial number 2A531163 and above.

What is the difference between this impeller and a standard one?
This is a heavy-duty impeller that is 0.030 inches shorter than the standard version, a key functional difference for the specified engine applications. It also features an 8-blade design for robust performance.

How often should I replace the sea water pump impeller?
It is recommended to inspect the impeller annually and replace it every 1-2 seasons or every 100-200 hours of operation. If you frequently operate in sandy or silty water, or if the pump has been run dry, more frequent replacement may be necessary.

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.