Upper Water Pump Repair Kit – Fits MerCruiser Alpha One Gen II (Replaces 817275Q05)

Upper Water Pump Repair Kit – Fits MerCruiser Alpha One Gen II (Replaces 817275Q05)

This is an aftermarket upper water pump repair kit designed for MerCruiser Alpha One Generation II stern drive units manufactured from 1991 and newer (serial numbers 0D469859 and up). It provides a reliable, direct-fit solution for maintaining your engine's cooling system.

This kit serves as a direct replacement for Mercury part numbers 817275Q05 and 817275K05, as well as Sierra 18-3147 and GLM 12043.

• Includes all necessary components for a complete upper unit overhaul, including the housing, impeller, gaskets, and plates.
• Features a durable stainless steel housing for corrosion resistance and longevity.
• Engineered for a direct fit, simplifying the installation process.

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.

MerCruiser

Mercury Marine

Technical Specifications

Package Contents

• 1 x Upper Housing
• 1 x Impeller
• 1 x Key (for impeller)
• 1 x Gasket, Water Pump Base
• 1 x O-ring
• Multiple x Water Guide Fittings
• Multiple x Additional Gaskets and Plates
• 1 x Face Seal with Installation Tool (Note: may not be in all kits)

Installation Guide

1. Safety First: Disconnect the boat's battery before beginning any work.
2. Drain Fluid: Place a drain pan under the stern drive and remove the gear lube drain/fill screws to empty the fluid.
3. Separate Drive: Remove the trim ram nuts and the main nuts holding the Alpha drive to the bell housing. Carefully separate the drive unit.
4. Access Pump: With the drive separated, locate the upper water pump assembly. Remove the bolts securing the pump housing.
5. Remove Old Pump: Lift off the old pump housing. Remove the old impeller, key, wear plate, and gaskets.
6. Clean Surfaces: Thoroughly clean all mating surfaces, ensuring they are free of old gasket material and corrosion.
7. Install New Kit: Assemble the new kit in reverse order. Place the new base gasket, plate, impeller, and key.
8. Seat Housing: Install the new O-rings and guide fittings. Carefully slide the new housing into place and tighten the bolts to the manufacturer's specified torque.
9. Reassemble Drive: Re-attach the stern drive to the bell housing, ensuring the driveshaft and water tube align correctly.
10. Refill & Test: Refill the drive with fresh gear lube. Reconnect the battery, start the engine using a water supply (muffs), and confirm a steady water stream from the tell-tale outlet.

Troubleshooting & FAQ

Q: How do I confirm this fits my Alpha One Gen II?

A: This kit is specifically for MerCruiser Alpha One Gen II drives. You must verify your drive's serial number. It fits units with serial numbers 0D469859 and higher. If your serial number is lower, you likely have a Gen I drive, which requires a different kit.

Q: What are the symptoms of a failing water pump?

A: The most common sign is the engine running hotter than normal or overheating. Other indicators include a weak or non-existent water stream from the "tell-tale" outlet, or finding brittle, cracked, or broken vanes on the impeller during a visual inspection.

Q: How frequently should the water pump impeller be replaced?

A: As a critical preventative maintenance item, it is best practice to inspect the impeller annually. We recommend replacing it every 1-2 years or every 100-200 hours of operation, whichever comes first, especially if you operate in saltwater or debris-heavy water.

Q: OEM vs. Aftermarket?

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.