Water Pump Impeller Kit – Fits MerCruiser Alpha One Gen 2 & Mercury Marine 200-250 HP Outboards (Replaces 817275A5, 817275Q05)

Water Pump Impeller Kit – Fits MerCruiser Alpha One Gen 2 & Mercury Marine 200-250 HP Outboards

This water pump impeller kit is a direct replacement for MerCruiser Alpha One Gen 2 stern drives (1991-present) and Mercury/Mariner 3.0L V6 outboards (200–250 HP). It provides a complete assembly for servicing or rebuilding the lower unit water pump.

It is designed to replace Mercury Marine part number 817275A5 and MerCruiser part numbers 817275K05, 817275Q05, 817275A6, 817275A4, 817275T4, and 817275Q4.

• Installation: Vehicle-specific fit for listed models.
• Materials: Features a durable neoprene impeller, stainless steel housing, and non-asbestos gaskets for reliable, long-lasting performance.
• Complete Assembly: Includes all necessary seals, gaskets, O-rings, and hardware for a full replacement.

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.

Mercury Marine / Mariner

MerCruiser

Technical Specifications

Package Contents

• 1 x Carrier Seal (821759A4)
• 1 x Impeller (47-43026T2)
• 1 x Impeller Plate (8172761)
• 1 x Impeller Key (28-43037)
• 2 x O-Ring (25-21836)
• 1 x Seal Ring Gasket (26-45577B1)
• 1 x Face Seal and Tool (26-816575A2)
• 1 x Impeller Gasket (27-430331)
• 1 x Impeller Gasket (27-8172771)
• 1 x Drain Screw Gasket (12-191833)

Installation Guide

Warning: Ensure the engine is turned off and the battery is disconnected before beginning installation. Use caution as components may be hot.

1. Disconnect the shift cable from the engine.
2. Remove the bolts securing the lower unit (gearcase) to the upper driveshaft housing.
3. Carefully lower the gearcase to access the water pump assembly. Be prepared for some gear lube to drain out.
4. Remove the bolts holding the water pump housing cover in place.
5. Remove the old impeller, gaskets, wear plate, and seals from the housing. Clean all surfaces thoroughly.
6. Install the new wear plate and gaskets.
7. Slide the new impeller into the housing. Turn the driveshaft clockwise to help seat the impeller vanes correctly.
8. Apply a light coat of marine grease to the inside of the housing and on the new O-rings and seals before installation.
9. Install the new seals and reassemble the pump housing, ensuring all bolts are torqued to manufacturer specifications.
10. Reinstall the gearcase onto the driveshaft housing, making sure the driveshaft, water tube, and shift shaft align correctly.
11. Secure the lower unit with the mounting bolts and reconnect the shift linkage.
12. Test the engine using a water supply (flushing muffs) to confirm proper water flow from the tell-tale outlet.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my specific engine?
A: The surest way is to match your engine's serial number to the ranges listed in the compatibility table. The serial number is typically found on a plate on the transom bracket. If you are unsure, use the serial number guide links provided above or consult your owner's manual.

Q: What are the signs of a failing water pump impeller?
A: Common symptoms include a weak or non-existent water stream from the "tell-tale" outlet, engine overheating alarms, and reduced engine performance. A visual inspection may reveal brittle, cracked, or missing impeller vanes.

Q: How often should the water pump impeller be replaced?
A: As a general rule, it's recommended to inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of use, depending on operating conditions (especially in saltwater or sandy/silty 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.