Complete Water Pump Kit – Fits MerCruiser MC-1/R/MR/Alpha One (Replaces 46-64141A11)
Complete Water Pump Kit – Fits MerCruiser MC-1/R/MR/Alpha One (Replaces 46-64141A11) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
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.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Product Details
This Complete Water Pump Kit – Fits MerCruiser MC-1/R/MR/Alpha One (Replaces 46-64141A11) is engineered for MerCruiser MC-1 sterndrive units (1969 and older) and R/MR/Alpha One sterndrive units (1970–1990). The kit contains all the essential components required for a comprehensive water pump service, restoring your engine's cooling system performance.
It serves as a direct interchange for a wide range of Mercury and MerCruiser part numbers, including 46-64141A11, 46-96148A8, 46-96148A5, and others, ensuring broad compatibility with specified models.
- Installs directly, matching OEM specifications for a precise fit.
- Kit includes both upper and lower housings for a complete overhaul.
- Comes with all necessary gaskets, seals, and a new impeller.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/MerCruiser | 46-64141A11 |
| Mercury/MerCruiser | 46-96148A8 |
| Mercury/MerCruiser | 46-96148A5 |
| Mercury/MerCruiser | 46-96148B8 |
| Mercury/MerCruiser | 46-58618A4 |
| Mercury/MerCruiser | 46-78400A2 |
| Mercury/MerCruiser | 46-73802A3 |
| Mercury/MerCruiser | 46-73804A3 |
| Mercury/MerCruiser | 46-96148B5 |
| Mercury/MerCruiser | 46-57234A3 |
| Mercury/MerCruiser | 46-60367A4 |
| Mercury/MerCruiser | 46-48747A3 |
| Mercury/MerCruiser | 46-44292A4 |
| Mercury/MerCruiser | 46-42579A4 |
| Mercury/MerCruiser | 46-69222A3 |
| Sierra | 18-3317 |
| Sierra | 18-3321 |
| GLM | 12110 |
| GLM | 12130 |
| Mallory | 9-48305 |
| Mallory | 9-48310 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|
| MerCruiser | MC-1 | All | 1969 & older | 46-64141A11 | Serial numbers up to 2791956 |
| MerCruiser | R | All | 1974–1982 | 46-64141A11 | Serial # 2791957-6225576 with preload pin on vertical drive shaft |
| MerCruiser | MR | All | 1983–1990 | 46-96148A8 | Alpha One transom assembly |
| MerCruiser | Alpha One | All | 1983–1990 | 46-96148A8 | Alpha One sterndrive |
| MerCruiser | 120/140 | 120/140 | 1970–1982 | 46-64141A11 | |
| MerCruiser | 165 | 165 | 1970–1982 | 46-64141A11 | |
| MerCruiser | 470 | 170 | 1976–1982 | 46-64141A11 | |
| MerCruiser | 485 | 185 | 1980–1982 | 46-64141A11 | |
| MerCruiser | 888 | 188 | 1971–1977 | 46-64141A11 | |
| MerCruiser | 228 | 228 | 1978–1982 | 46-64141A11 | |
| MerCruiser | 898/228 | 228 | 1977–1982 | 46-64141A11 | |
| MerCruiser | 233 | 233 | 1975–1977 | 46-64141A11 | |
| MerCruiser | 250 | 250 | 1977 | 46-64141A11 | |
| MerCruiser | 260 | 260 | 1978–1982 | 46-64141A11 | |
| MerCruiser | 225-S | 225 | 1974 | 46-64141A11 |
Technical Specs
- Product Type
- Complete Water Pump Kit
- Installation
- Direct replacement for MerCruiser stern drives
- Connection
- Direct mounting to sterndrive
- Dimensions
- 5.25" H x 4.75" W x 3.5" L
- Fitting Type
- Direct fit to OEM specifications
- Other Technical Attributes
- Includes upper and lower housings and all gaskets, seals, guide tube, and impeller
What’s in the Box
- 1 x Water Pump Upper Housing
- 1 x Water Pump Lower Housing
- 1 x Impeller
- All required gaskets, O-rings, and seals
- 1 x Water Guide Tube
Installation Notes
- Disconnect the battery and ensure the engine is off and cool.
- Place the drive in forward gear and drain the gearcase oil from the lower unit.
- Remove the lower unit (outdrive) from the upper housing assembly.
- Unbolt and carefully 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 gaskets, base plate, impeller, and pump housing from the kit. Ensure the impeller key is correctly placed.
- Lightly lubricate the interior of the new housing and the impeller with marine grease.
- Reinstall the water pump assembly, torquing bolts to manufacturer specifications.
- Re-install the lower unit, ensuring the water tube, shift shaft, and drive shaft align correctly.
- Refill the gearcase with the proper grade and amount of lubricant before operation.
Troubleshooting & FAQ
How do I know if this water pump kit fits my engine?
This kit fits MerCruiser MC-1 (pre-1970) and R/MR/Alpha One drives (1970-1990). The key is to match your model, year, and serial number range against the compatibility table. For R-drives, this specific kit is for models with a preload pin on the vertical drive shaft.
What are the signs of a failing water pump?
Common symptoms include the engine overheating at idle or low speeds, a weak or no stream of water from the "telltale" outlet, and a dry, cracked, or brittle impeller upon inspection. A damaged housing can also reduce water pressure.
How often should the water pump impeller be replaced?
As a general maintenance rule, the impeller should be inspected annually and replaced every 1-2 years, regardless of appearance. For boats used in saltwater or sandy/silty conditions, annual replacement is strongly recommended to prevent overheating.
What is the difference between this kit and just an impeller?
This is a complete kit that includes the upper and lower pump housings, gaskets, seals, and guide tube in addition to the impeller. Replacing the full assembly is recommended if the old housing is scored, warped, or corroded, as a new impeller in a worn housing will not produce adequate pressure.
Why are there two different Sierra/GLM part numbers listed?
Aftermarket manufacturers often create slightly different kits; for example, one might include the upper and lower housing (like this one), while another might only include the lower housing and impeller. Both cross-reference to the same OEM application but may vary in contents.
Is any special grease needed for installation?
Yes, it's highly recommended to use a 2-4-C marine lubricant or a similar waterproof marine grease on the impeller and inside the pump housing to ensure a good seal and provide lubrication during the initial dry startup.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns?
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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