Water Pump Repair Kit – Fits Mercury/Mariner Outboards & MerCruiser Alpha One Gen II (Replaces 8M0100526, 47-8M0100526)

Water Pump Repair Kit – Fits Mercury/Mariner Outboards & MerCruiser Alpha One Gen II

This water pump repair kit is a direct replacement for various Mercury/Mariner outboards and MerCruiser Alpha One Gen II sterndrives. It provides the necessary components for a complete overhaul of your water pump assembly, restoring cooling system performance and reliability.

This kit fits a wide range of engines, including Mercury/Mariner 40–115 HP 4-Stroke models, 60–250 HP 2-Stroke models, and Verado 4 & 6-cylinder outboards with 4.80" torpedo gearcases. It is also compatible with MerCruiser Alpha One Gen II sterndrives (serial number 0D469859 and above).

• Includes a complete 15-piece kit with impeller, gaskets, seals, and O-rings for a full service.
• Engineered for direct OEM replacement, ensuring proper fit and function.
• Impeller elastomers are designed for improved flexibility across a broad range of temperatures and provide enhanced flow rates for better cooling.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers. This kit is a direct replacement for the following parts:

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.

Mercury/Mariner Outboards

MerCruiser Sterndrives

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (8M0025709)
• 1 x Impeller Drive Key (8M0032833)
• 1 x Water Pump Faceplate (8172761)
• 1 x Water Pump Gasket (8172771)
• 1 x Faceplate Gasket (8M0050720)
• 1 x Face Seal (8M2014338)
• 1 x Face Seal Setting Tool (818769)
• 1 x Quad Ring (455771)
• 2 x O-ring (0.796 in. x 0.139 in.) (21836)
• 1 x O-ring (0.921 in. x 0.139 in.) (90196)
• 2 x Drain Plug Seal (830749)

Installation Guide

1. Disconnect the battery cables from the battery.
2. Place a drain pan under the lower unit and remove the gearcase lubricant drain screw to empty the old oil.
3. Remove the bolts securing the lower unit (gearcase) to the engine.
4. Carefully lower and remove the gearcase from the drive shaft housing.
5. Unbolt and remove the old water pump housing, impeller, faceplate, and gaskets. Note the orientation of the old parts.
6. Thoroughly clean the mating surfaces on the gearcase where the new pump will be installed.
7. Install the new gaskets, faceplate, and drive key.
8. Slide the new impeller onto the drive shaft, rotating it in the correct direction (typically clockwise) while pushing down.
9. Lubricate the inside of the new pump housing and install it over the impeller, ensuring a proper seal. Torque bolts to manufacturer specifications.
10. Reinstall the lower unit onto the engine, making sure the driveshaft, shift shaft, and water tube align correctly.
11. Refill the gearcase with the recommended marine gear lubricant before reinstalling and tightening the drain plug seals.
12. Reconnect the battery, start the engine in a suitable water supply, and verify a steady stream of water from the cooling system's tell-tale outlet.

Troubleshooting & FAQ

How do I confirm this kit fits my engine?

Review the "Compatible Engine Models" tables to verify that your specific model and serial number range are listed. For Mercury/Mariner and MerCruiser owners, we strongly recommend using the serial number lookup guides linked above to guarantee an exact match before ordering.

What are the signs my water pump needs replacing?

A failing water pump can cause serious engine damage. Key signs include a weak or non-existent water stream from the "tell-tale" outlet, frequent engine overheating alarms, or a noticeably higher-than-normal engine temperature reading on your gauges.

How often should I replace my water pump impeller?

For preventative maintenance, it is recommended to inspect the impeller annually and replace the entire water pump kit every 1-2 years or every 100-200 hours of operation. Service intervals should be shorter for boats used in saltwater or in water with high levels of sand or silt.

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.