Sea Water Pump Impeller Repair Kit – Fits MerCruiser 4.5L & 6.2L (Replaces 8M0137221, 8M0137220, 8M0121940)
Sea Water Pump Impeller Repair Kit – Fits MerCruiser 4.5L & 6.2L (Replaces 8M0137221, 8M0137220, 8M0121940) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
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Sea Water Pump Impeller Repair Kit – Fits MerCruiser 4.5L & 6.2...
Sea Water Pump Impeller Repair Kit – Fits MerCruiser 4.5L & 6.2L (Replaces 8M0137221, 8M0137220, 8M0121940) is backordered and will ship as soon as it is back in stock.
Product Details
This heavy-duty Sea Water Pump Impeller Repair Kit is engineered for Mercury MerCruiser 4.5L V6 and 6.2L V8 sterndrive and inboard engines from 2014 and newer (serial numbers 2A531163 and up). It provides a complete solution for servicing your engine's raw water pump to restore cooling performance.
It serves as a direct replacement for Mercury/Quicksilver part numbers 8M0137221, 8M0121940, and 8M0137220, as well as GLM Marine equivalents 89703 and 89704.
- Installs directly into the sea water pump assembly.
- Features a high-flow design for improved engine cooling efficiency.
- Includes the impeller and both front and rear wear plates for a comprehensive service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/Quicksilver | 8M0137221 |
| Mercury/Quicksilver | 8M0121940 |
| Mercury/Quicksilver | 8M0137220 |
| GLM Marine | 89703 |
| GLM Marine | 89704 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury MerCruiser models, it is critical to verify your engine's serial number falls within the specified range to ensure correct fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury MerCruiser | 4.5L MCM | 4-Stroke | 2014+ (s/n 2A531163+) | 8M0137221 | ||
| Mercury MerCruiser | 6.2L MCM (sterndrive) | 4-Stroke | 2014+ (s/n 2A531197+) | 8M0137221 | ||
| Mercury MerCruiser | 6.2L MIE (inboard) | 4-Stroke | 2014+ (s/n 2A530774+) | 8M0137221 | ||
| Mercury MerCruiser | 6.2L TowSport | 4-Stroke | 2014+ (s/n 2A531348+) | 8M0137221 |
Technical Specs
- Product Type
- Heavy Duty Sea Water Pump Impeller Repair Kit
- Installation
- Direct replacement in sea water pump assembly
- Housing Material
- Marine Grade Nylon, Metal, Plastic
- Housing Color
- Black
- Other Technical Attributes
- High flow design for improved engine cooling
What’s in the Box
- 1 x Water Pump Impeller
- 2 x Wear Plates (1 x Rear wear plate, 1 x Overmolded inner/front wear plate)
Installation Notes
Installation should be performed by a qualified marine mechanic. Always refer to your engine's official service manual for detailed procedures, safety precautions, and torque specifications. Ensure the engine is off, the battery is disconnected, and the seacock is closed before beginning work. Upon installation, briefly run the engine and check for proper water flow and leaks.
Troubleshooting & FAQ
How do I know if this impeller kit fits my MerCruiser engine?
Check your engine's serial number. This kit is designed for 4.5L V6 and 6.2L V8 models from 2014 and newer, with serial numbers 2A531163 and above. Always cross-reference the OEM part numbers listed (8M0137221, 8M0137220, 8M0121940) with your service manual to guarantee compatibility.
What are the signs of a failing water pump impeller?
Common symptoms include rising engine temperatures at idle or low speeds, a noticeable reduction in water flow from the exhaust, or finding pieces of black rubber impeller vanes in the cooling system, heat exchanger, or thermostat housing.
How often should the sea water pump impeller be replaced?
For preventative maintenance, it's recommended to inspect the impeller annually and replace it every 100-200 operating hours or every 2–3 years, whichever comes first. This applies even if it appears undamaged, as the rubber can become brittle over time.
Is there a difference in cooling performance with this kit?
This kit features a high-flow impeller design engineered to meet or exceed OEM specifications, ensuring efficient engine cooling under normal operating conditions.
Can I replace just the impeller and not the wear plates?
While possible, it is highly recommended to replace the wear plates included in the kit. Worn or scored plates can reduce pump efficiency and cause premature failure of the new impeller.
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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