Water Pump Impeller Kit – Fits Mercury/Mariner 40-250 HP and MerCruiser Alpha One Gen 2 (Replaces 47-43026Q06)

Water Pump Impeller Kit – Fits Mercury/Mariner 40-250 HP and MerCruiser Alpha One Gen 2 (Replaces 47-43026Q06)

This water pump impeller service kit provides all the necessary components to restore the cooling system on a wide range of Mercury/Mariner outboards, MerCruiser Alpha One Generation 2 stern drives, and select Honda outboards. Engineered for durability and a precise fit, it ensures your engine maintains optimal operating temperature, preventing overheating and potential damage.

It serves as a direct replacement for multiple OEM and aftermarket part numbers, including Mercury 47-43026Q06 and 47-8M0100526, Sierra 18-3214, and Honda 19021-ZW1-003, offering a reliable and cost-effective solution for your marine maintenance needs.

• Direct Replacement: Designed to meet or exceed OEM specifications for a perfect fit and reliable performance.
• Complete Kit: Includes the neoprene impeller, wear plate, gaskets, seals, and other hardware required for a full service.
• Broad Compatibility: Fits a vast range of outboards and stern drives from 1991 to current models.

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 and MerCruiser 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 Stern Drives

Honda Outboards

Confirm your engine model/year in the table below.

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (Replaces 47-43026T2)
• 1 x Impeller Plate (Replaces 817276)
• 1 x Impeller Key (Replaces 28-43037)
• 1 x Impeller Gasket (Replaces 27-817277)
• 1 x Impeller Gasket (Replaces 27-430331)
• 1 x Face Seal (Replaces 26-816575A2)
• 1 x Coupling Assembly (Replaces 816597A1) - For Alpha One Gen 2 applications only
• 4 x O-Ring (Replaces 25-21836)

Note: Package contents are based on our most recent inventory. While contents may vary slightly, each kit is guaranteed to include all necessary components for a complete service.

Installation Guide

Professional installation is recommended. The following are general steps for replacing a water pump impeller:

1. Disconnect Power: Disconnect the negative battery cable for safety.
2. Drain Gear Lube: Place a drain pan under the lower unit and remove the upper and lower gear lube drain screws to drain the oil.
3. Remove Lower Unit: Remove the bolts securing the lower unit (gearcase) and carefully lower it from the engine.
4. Access Impeller: Unbolt and remove the water pump housing cover to expose the old impeller.
5. Inspect and Remove: Note the rotational direction of the old impeller blades. Remove the old impeller, wear plate, gaskets, and seals.
6. Clean Surfaces: Thoroughly clean all mating surfaces, removing any old gasket material or corrosion.
7. Install New Components: Install the new wear plate, gaskets, and impeller key onto the driveshaft.
8. Install New Impeller: Lubricate the inside of the pump housing. Slide the new impeller onto the driveshaft while turning the shaft clockwise to seat the blades correctly.
9. Reassemble Pump: Reinstall the water pump housing and torque the bolts to the manufacturer's specified value.
10. Reinstall Lower Unit: Guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube are properly aligned. Secure with bolts.
11. Refill Gear Lube: Fill the gearcase with fresh marine gear lube from the bottom drain hole until it seeps out the top hole, then reinstall both drain screws.
12. Test Operation: Connect a water supply (flushing muffs). Start the engine and confirm a steady stream of water from the telltale outlet.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my engine?
A: The most reliable method is to match the part number from your old impeller or service manual to the numbers in our Part Number Cross-Reference table. Additionally, verify your engine's model, year, and serial number against our compatibility tables. For MerCruiser Alpha One Gen 2 drives, this kit fits serial numbers 0D469859 and up.

Q: What are the signs of a failing water pump impeller?
A: Common symptoms include the engine overheating, a weak or intermittent water stream from the "tell-tale" outlet, and in some cases, a faint burning rubber smell. Upon inspection, a worn impeller may have cracked, brittle, or missing blades.

Q: How often should I replace the impeller?
A: As a critical maintenance item, we recommend replacing your impeller every 1-2 years or every 100-200 hours of use, whichever comes first. More frequent changes may be necessary if you operate in sandy, silty, or saltwater environments.

Q: This is an aftermarket part. How does it compare to OEM?
A: 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.

Q: How fast do you ship and how much does it cost?
A: 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.

Q: What is your warranty and return policy?
A: 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.