Water Pump Impeller Kit – Fits Mercury/MerCruiser Alpha One Gen 2 & Outboard 40-250 HP (Replaces 8M0100526, 47-43026Q06)

Water Pump Impeller Kit – Fits Mercury/MerCruiser Alpha One Gen 2 & Outboard 40-250 HP

This water pump impeller repair kit is designed for a wide range of Mercury and MerCruiser engines, including Alpha One Gen 2 sterndrives (1998+) and various 2-stroke and 4-stroke outboards from 40 HP to 275 HP. It provides a reliable solution for maintaining your engine's cooling system for optimal performance and longevity.

This kit serves as a direct replacement for Mercury/Quicksilver part numbers 8M0100526, 47-8M0100526, 47-43026Q06, 43026T10, 43026T8, 43026T7, 43026T6, 43026T11, 43026Q5, and Sierra 18-3265.

• Complete Repair Kit: Includes the impeller, housing, faceplate, gaskets, seals, and drive key for a full service.
• Enhanced Durability: Features advanced impeller elastomers for improved flexibility across a broad range of temperatures and redesigned for better flow rates.
• Direct Installation: Engineered to match OEM specifications for a direct fit, requiring only basic tools for installation.

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 (8M0025709, 47-43026Q02)
• 1 x Impeller Drive Key (8M0032833, 28-43037)
• 2 x O-ring (0.796 in. x 0.139 in.) (21836, 25-21836)
• 1 x O-ring (0.921 in. x 0.139 in.) (90196, 25-90196, 18-7178)
• 1 x Quad Ring/Seal Ring (455771, 26-45577)
• 1 x Faceplate Gasket (8M0050720, 27-43033-1)
• 1 x Water Pump Faceplate (8172761)
• 1 x Water Pump Gasket (8172771, 27-8172771)
• 1 x Face Seal (8M2014338, 26-816575A2)
• 1 x Face Seal Setting Tool (818769)
• 2 x Drain Plug Seal (830749, 26-830749)
• 1 x Water Tube (32-860220) - Note: This part is included in some kits only.

Installation Guide

1. Safety First: Disconnect the battery and ensure the engine is in a stable, secure position.
2. Drain Gearcase Oil: Place a drain pan under the lower unit and remove the upper and lower gearcase oil drain screws to drain the oil.
3. Remove Lower Unit: Remove the bolts securing the lower unit (gearcase) to the upper driveshaft housing. Carefully separate the lower unit.
4. Access the Water Pump: With the lower unit removed, locate and unbolt the water pump housing cover.
5. Remove Old Components: Take note of the orientation of all parts. Remove the old impeller, gaskets, faceplate, and seals from the housing.
6. Clean and Inspect: Thoroughly clean the housing and all mating surfaces. Inspect the housing for any scoring, cracks, or warping.
7. Install New Components: Lightly grease the new seals and O-rings. Install the new faceplate, gaskets, and drive key from the kit.
8. Install New Impeller: Lubricate the inside of the housing and the new impeller. Slide the impeller onto the driveshaft, turning the shaft clockwise to seat the vanes correctly.
9. Reassemble Pump: Install the new housing cover and tighten the bolts to the manufacturer's specified torque.
10. Reattach Lower Unit: Reinstall the lower unit, ensuring the driveshaft, shift shaft, and water tube align correctly. Secure with bolts.
11. Refill Gearcase Oil: Fill the gearcase with fresh marine gear lube from the bottom drain hole until it seeps out the top hole. Reinstall drain screws with new seals.
12. Test Operation: Reconnect the battery. Start the engine using a water supply (flushing muffs) and verify a steady stream of water from the tell-tale outlet.

Troubleshooting & FAQ

The most reliable method is to match your engine's serial number to the ranges listed in the "Compatible Engine Models" table. If your serial number falls within the specified range for your model, this kit is compatible.

Common symptoms include the engine overheating at idle or low speeds, a weak or non-existent water stream from the "tell-tale" outlet, and in some cases, a high temperature alarm from your engine's monitoring system.

As a preventative maintenance measure, it is widely recommended to replace your impeller every 1-2 years or every 100-200 hours of operation, whichever comes first. This can vary based on your operating conditions (e.g., saltwater vs. freshwater).

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.

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.

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.