Water Pump Impeller Repair Kit – Fits MerCruiser Alpha One Gen II & Vazer Drives (Replaces 817275Q05)

$74.00

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Water Pump Impeller Repair Kit – Fits MerCruiser Alpha One Gen II & Vazer Drives (Replaces 817275Q05) is backordered and will ship as soon as it is back in stock.

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You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

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Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This is a complete upper Water Pump Impeller Repair Kit for MerCruiser Alpha One Gen II sterndrive units (1991–present, serial numbers D469859 and up) and all MerCruiser Vazer drives. It provides everything needed for a full service of the upper water pump housing.

This kit serves as a direct replacement for multiple OEM and aftermarket part numbers, including Mercury MerCruiser 817275Q05, 817275A-series, Sierra 18-3147, and GLM 12414.

Engineered for direct OEM replacement fit and function.
Features a durable one-piece stainless steel housing.
Includes a new impeller, wear plate, gaskets, and all related hardware for a complete job.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Mercury MerCruiser	817275Q05
Mercury MerCruiser	817275A4
Mercury MerCruiser	817275A5
Mercury MerCruiser	817275K05
Mercury MerCruiser	817275Q4
Mercury MerCruiser	817275T4
Mercury MerCruiser	847275A5
Mercury MerCruiser	817275A1
Sierra	18-3147
GLM	12414

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For MerCruiser applications, this kit fits Alpha One Gen II and Vazer drives. Please verify your drive's serial number is D469859 or newer.

For Mercury Outboard applications, this kit fits specific 3.0L V6 2-stroke models. Check your engine's serial number against the ranges provided.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
MerCruiser	Alpha One Gen II Drive	N/A	N/A	1991–1997	817275Q05	Serial numbers D469859–0F679999
MerCruiser	Alpha One Gen II Drive	N/A	N/A	1997–1998	817275Q05	Serial numbers 0F680000–0K999999
MerCruiser	Alpha One Gen II Drive	N/A	N/A	1998+	817275Q05	Serial numbers 0L100040 & Up
MerCruiser	Vazer Drive	N/A	N/A	All Years	817275Q05
Mercury	225 (3.0L Carb)	225	2-Stroke	All Years	817275Q05	Serial numbers 0D280813-0G760299
Mercury	225 (3.0L EFI)	225	2-Stroke	All Years	817275Q05	Serial numbers 0G129222-0G760299
Mercury	225 Marathon (3.0L Carb)	225	2-Stroke	All Years	817275Q05	Serial numbers 0G245605-0G760299
Mercury	225 SeaPro (3.0L Carb)	225	2-Stroke	All Years	817275Q05	Serial numbers 0G245605-0G760299
Mercury	250 (3.0L EFI)	250	2-Stroke	All Years	817275Q05	Serial numbers 0G129222-0G760299

Technical Specs

Product Type: Upper Water Pump Repair Kit
Installation: Direct OEM replacement
Housing Material: Stainless steel (one-piece body)
Warranty: Manufacturer warranty against defects
Other Technical Attributes: Complete 11-piece kit

What’s in the Box

1 x Upper Water Pump Housing
1 x Impeller (47-43026T-2)
1 x Water Guide Fittings
1 x Impeller Plate
1 x Key
1 x Gasket
1 x O-Ring

Installation Notes

Disconnect the negative battery terminal for safety.
Remove the sterndrive unit from the transom assembly according to your service manual.
Separate the upper gearcase from the lower unit to access the water pump.
Unbolt and remove the old water pump housing, impeller, and wear plate.
Thoroughly clean all mating surfaces, removing any old gasket material or sealant.
Install the new gasket, wear plate, and key onto the driveshaft.
Slide the new impeller onto the driveshaft, turning it clockwise to align with the key.
Install the new O-ring and gasket on the housing, then fasten the new housing in place. Torque bolts to manufacturer specifications.
Reassemble the lower and upper units and reinstall the complete sterndrive.
Reconnect the battery and test for proper cooling system operation with the drive submerged in water.

Troubleshooting & FAQ

How do I know if this kit fits my Alpha One Gen II drive?

This kit is designed for MerCruiser Alpha One Gen II sterndrives manufactured from 1991 to the present. You must verify that your drive's serial number is D469859 or higher. It will not fit Gen I drives.

What are the signs of a failing water pump impeller?

Common symptoms include the engine overheating at idle or low speeds, a weak or no stream of water from the tell-tale outlet, and a low water pressure reading on the gauge. A visual inspection may show a brittle, cracked, or melted impeller.

How often should I replace my sterndrive's water pump impeller?

For preventative maintenance, it is recommended to replace the impeller every 1 to 2 years, or every 100-200 hours of engine operation. Service intervals can vary based on usage (freshwater vs. saltwater) and operating conditions.

Is this a complete kit for the upper water pump service?

Yes, this is a comprehensive 11-piece kit that includes the upper housing, impeller, wear plate, key, gaskets, O-rings, and other necessary components for a full replacement of the upper water pump assembly.

Will this kit also fit a MerCruiser Alpha One Gen 1 drive?

No. This kit is only compatible with Alpha One Gen II drives (1991 and newer) and Vazer drives. Gen I drives require a different water pump kit.

What is the difference between this and the genuine OEM kit?

This is an aftermarket replacement part, not an OEM component. It is engineered to meet or exceed original equipment specifications using comparable high-quality materials, such as a one-piece stainless steel housing for improved durability. It offers the same fit and function at a more accessible price.

What is your policy on shipping speed and cost?

We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free to most locations, and expedited options will appear at checkout if they are available for your address.

What is the warranty and return policy?

This product is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard window for items that are unused and in original condition. See our full policy page or reach out for return instructions.

Is this an OEM or aftermarket part?

This listing is for a high-quality aftermarket replacement part (not OEM). It is built to OEM-level specifications with comparable materials. Our components are manufactured in an ISO 9002 certified facility and are batch-inspected to ensure quality and consistency.

Safety & Important Info

Verify images and specifications against your original part before purchasing. If anything differs—even if your model appears on a compatibility list—do not install the part.
This is an aftermarket replacement component, not a genuine OEM part. Brand names and part numbers are used for reference purposes only.
Professional installation is highly recommended for all marine engine components to ensure safety and proper performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world reliability.
Fast Global Fulfillment — We offer free standard delivery to most regions, with an average transit time of 5–15 days.
Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.

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