Water Pump Impeller Kit for MerCruiser Alpha One Gen II Sterndrives and Mercury/Mariner 200–250 HP 3.0L Outboards — Replaces 817275A5 and 817275Q05
Water Pump Impeller Kit for MerCruiser Alpha One Gen II Sterndrives and Mercury/Mariner 200–250 HP 3.0L Outboards — Replaces 817275A5 and 817275Q05 is backordered and will ship as soon as it is back in stock.
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Water Pump Impeller Kit for MerCruiser Alpha One Gen II Sterndrives...
Water Pump Impeller Kit for MerCruiser Alpha One Gen II Sterndrives and Mercury/Mariner 200–250 HP 3.0L Outboards — Replaces 817275A5 and 817275Q05 is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit is an aftermarket replacement water-pump service kit for specified Mercury and Mariner 200–250 HP 3.0L outboards and MerCruiser Alpha One Generation II sterndrives. It is designed to restore water-pump performance and help maintain proper engine cooling when the original impeller, wear plate, seals, or related service components are worn.
The kit is listed as a replacement for Mercury Marine 817275A5 and related MerCruiser references including 817275K05, 817275Q05, 817275A6, 817275A4, 817275T4, and 817275Q4. Additional aftermarket reference numbers include Sierra 18-3147 and Mallory 9-48315. Confirm the complete model, year, stroke, and serial-number range before ordering; part-number similarity alone does not establish fitment.
- Application-specific water-pump service kit for listed marine engines and sterndrives.
- Neoprene impeller with stainless-steel pump and wear components.
- Includes gaskets, seals, O-rings, impeller key, and related service hardware listed below.
- Aftermarket replacement part; not manufactured or sold as an OEM component.
Part Number Matrix
Use the following references together with your engine identification information when checking replacement compatibility.
| Brand | Part Number |
|---|---|
| Mercury Marine | 817275A5 |
| MerCruiser | 817275K05 / 817275Q05 / 817275A6 / 817275A4 / 817275T4 / 817275Q4 |
| Sierra | 18-3147 |
| Mallory | 9-48315 |
Engine and Model Compatibility
The compatibility information below is provided for identification and cross-reference purposes. Mercury and Mariner outboard fitment depends on the exact model configuration and serial number. The listed DFI, EFI, and carbureted 3.0L applications are two-stroke outboard applications; do not use a generic four-stroke designation to determine fitment.
For MerCruiser applications, confirm that the drive is an Alpha One Generation II sterndrive. The water-pump arrangement and service parts differ between Alpha One Generation I and Generation II drives.
| Brand | Model | Rated HP | Stroke | Year Coverage | Reference | Serial Number |
|---|---|---|---|---|---|---|
| Mercury/Mariner | 200 DFI | 200 | 2-Stroke | Up to 2008 | 817275A5 | 0G590000–0T800999 |
| Mercury/Mariner | 200 DFI 3.0L | 200 | 2-Stroke | Up to 2010 | 817275A5 | 0T801000–1B504988 |
| Mercury | 200 DFI 3.0L DTS | 200 | 2-Stroke | Up to 2010 | 817275A5 | 0T980000–1B504988 |
| Mercury/Mariner | 200 EFI 3.0L | 200 | 2-Stroke | Up to 2010 | 817275A5 | 0T750164–1B504988 |
| Mercury/Mariner | 225 Carbureted 3.0L | 225 | 2-Stroke | Up to 2006 | 817275A5 | 0G760300–0T408999 |
| Mercury/Mariner | 225 DFI | 225 | 2-Stroke | Up to 2010 | 817275A5 | 0G590000–1B504988 |
| Mercury/Mariner | 225 DFI 3.0L | 225 | 2-Stroke | Up to 2010 | 817275A5 | 0T801000–1B504988 |
| Mercury/Mariner | 225 DFI 3.0L DTS | 225 | 2-Stroke | Up to 2010 | 817275A5 | 0T599000–1B504988 |
| Mercury/Mariner | 225 EFI 3.0L | 225 | 2-Stroke | Up to 2010 | 817275A5 | 0G760300–1B504988 |
| Mercury/Mariner | 225 EFI 3.0L SeaPro/Marathon | 225 | 2-Stroke | Up to 2009 | 817275A5 | 0T801000–1B417701 |
| Mercury | 225 Pro XS DFI 3.0L | 225 | 2-Stroke | Up to 2009 | 817275A5 | 1B104549–1B426560 |
| Mercury/Mariner | 225 SeaPro/Marathon Carbureted 3.0L | 225 | 2-Stroke | Up to 2006 | 817275A5 | 0G760300–0T408999 |
| Mercury/Mariner | 250 EFI 3.0L | 250 | 2-Stroke | Up to 2010 | 817275A5 | 0G760300–1B504988 |
| Mercury | 250XB EFI 3.0L | 250 | 2-Stroke | Up to 2008 | 817275A5 | 0G980600–0T800999 |
| Mercury/Mariner | 3.0L EFI SeaPro/Marathon | 200–250 | 2-Stroke | Up to 2008 | 817275A5 | 0T409000–0T800999 |
| Brand | Model | Drive Type | Year Coverage | Reference | Application Note |
|---|---|---|---|---|---|
| MerCruiser | Alpha One Generation II | Sterndrive | 1991 and later | 817275K05 / 817275Q05 | Confirm Generation II drive before purchase. |
Technical Specifications
- Product Type
- Water-pump impeller service kit with housing and related components
- Installation
- Application-specific replacement; verify model and serial number
- Fuel Type
- Gasoline marine engines
- Housing and Wear Components
- Stainless steel
- Impeller Material
- Neoprene
- Gasket Material
- Non-asbestos gasket material
- Weight
- Approximately 0.72 kg (1.59 lb)
What's in the Box
- 1 × Carrier seal — 821759A4
- 1 × Impeller — 47-43026T2
- 1 × Impeller plate — 8172761
- 1 × Impeller key — 28-43037
- 2 × O-ring — 25-21836
- 1 × Seal-ring gasket — 26-45577B1
- 1 × Face seal and installation tool — 26-816575A2
- 1 × Impeller gasket — 27-430331
- 1 × Impeller gasket — 27-8172771
- 1 × Drain-screw gasket — 12-191833
Installation Notes
- Disconnect the battery and place the engine or drive in neutral.
- Place a drain pan under the lower unit and remove the gearcase drain and fill screws to drain the oil.
- Remove the fasteners securing the lower unit or gearcase to the upper housing. Record the position of any different-length fasteners.
- Lower the gearcase carefully while disengaging the shift shaft and driveshaft.
- Remove the existing water-pump housing and impeller assembly.
- Clean all mounting and sealing surfaces, removing old gasket material and sealant.
- Install the new components in the correct order. Apply only the lubricant specified by the applicable service procedure, and ensure that the impeller key is fully seated.
- Install the water-pump assembly on the driveshaft and orient the impeller vanes according to the applicable manufacturer procedure.
- Reinstall the lower unit, aligning the driveshaft, water tube, and shift shaft.
- Install and tighten the fasteners to the manufacturer's specified torque.
- Refill the gearcase with the correct marine gear oil and reconnect the battery.
- Run the engine in the water or with an appropriate flushing attachment and verify normal cooling-water flow.
Troubleshooting and FAQ
How do I confirm fitment?
Compare the engine or sterndrive model, year, stroke, and complete serial number with the compatibility information above. For Mercury and Mariner outboards, the serial-number range is especially important. For MerCruiser applications, confirm that the drive is Alpha One Generation II rather than Generation I.
What are common signs of a worn water-pump impeller?
Possible symptoms include overheating at idle or low speed, weak cooling-water discharge, reduced water pressure, or a brittle, cracked, deformed, or missing impeller vane during inspection.
How often should the impeller be replaced?
Replacement intervals vary with the engine manufacturer's maintenance schedule and operating conditions. Inspect and replace the impeller at the recommended interval, and consider more frequent service when operating in sandy, silty, or saltwater conditions.
Is the face-seal installation tool included?
Yes. The listed package contents include the face seal and installation tool identified as 26-816575A2.
How can I distinguish Alpha One Generation II from Generation I?
Do not rely on appearance alone. Confirm the drive generation from the drive identification, service manual, original part number, or a qualified marine technician. Generation I and Generation II water-pump components are not automatically interchangeable.
Is this an OEM part?
No. This is an aftermarket replacement kit. The OEM and aftermarket numbers shown on this page are reference numbers used for identification and cross-reference purposes.
How fast do you ship?
Typical transit is 5–15 days, with standard shipping available to most locations. Expedited options may be available at checkout depending on destination.
What warranty and return coverage applies?
The kit is covered by a 1-year warranty against manufacturing defects under normal use. Returns are accepted within the applicable standard return window for unused parts in original condition. Contact support for current policy and return instructions.
Safety and Important Information
- Verify the complete engine or sterndrive identification and compare the original water-pump components before ordering.
- Do not assume compatibility from horsepower or a similar-looking part number alone.
- This is an aftermarket replacement, not an OEM component.
- Follow the applicable service manual and use a qualified marine technician when required.
About Sea Sierra
- Pro-Grade Standards — Marine replacement parts designed for demanding real-world service conditions.
- Fast Global Fulfillment — Standard delivery is available to most regions, with delivery timing depending on destination.
- Manufacturer-Direct Value — Competitive pricing supported by controlled materials and quality processes.
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