Water Pump Impeller Repair Kit – Fits Mercury Marine 15-20 EFI (Replaces 8M0135821, 46-8M0135821)
Water Pump Impeller Repair Kit – Fits Mercury Marine 15-20 EFI (Replaces 8M0135821, 46-8M0135821) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
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Water Pump Impeller Repair Kit – Fits Mercury Marine 15-20 EFI (Rep...
Water Pump Impeller Repair Kit – Fits Mercury Marine 15-20 EFI (Replaces 8M0135821, 46-8M0135821) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Repair Kit is designed for Mercury Marine 15–20 HP EFI 4-Stroke outboard motors (2006–Present) with serial numbers 0R833820 and above, including ProKicker and SeaPro models. It provides all necessary components for routine cooling system maintenance and restoration.
It serves as a direct aftermarket replacement for Mercury part numbers 8M0135821 and 46-8M0135821, and provides an interchange for Sierra 18-7913 and QuickMarine 8M0135821.
- Engineered as a direct OEM-spec replacement for a precise fit.
- Addresses common cooling system issues by replacing all wear items.
- Kit includes the impeller, housing, wear plate, seals, and gaskets.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 8M0135821 |
| Mercury | 46-8M0135821 |
| Sierra | 18-7913 |
| QuickMarine | 8M0135821 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit is designed for specific Mercury Marine EFI 4-Stroke models from 2006 to the present with serial numbers 0R833820 and higher. Verify your model and serial number before ordering.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | EFI | 15 | 4-Stroke | 2006–Present | 8M0135821 | Serial # 0R833820 & above |
| Mercury | EFI SeaPro | 15 | 4-Stroke | 2006–Present | 8M0135821 | Serial # 0R833820 & above |
| Mercury | EFI ProKicker | 15 | 4-Stroke | 2006–Present | 8M0135821 | Serial # 0R833820 & above |
| Mercury | EFI | 20 | 4-Stroke | 2006–Present | 8M0135821 | Serial # 0R833820 & above |
| Mercury | EFI | 10 | 4-Stroke | 2006–Present | 8M0135821 | Per PartsVu & Soxa Marine |
Technical Specs
- Product Type
- Water Pump Impeller Repair Kit
- Installation
- Direct OEM replacement
- Fuel Type
- Gasoline
- Housing Material
- Plastic, Metal, Rubber
- Housing Color
- Black/Silver
- Fitting Type
- Vehicle Specific Fit
- Other Technical Attributes
- For cooling system maintenance
What’s in the Box
- 1 x Water Pump Impeller (8M0135803)
- 1 x Housing (8M0134492)
- 1 x Insert Cup (803751)
- 1 x Wear Plate (8M0135805)
- 1 x Key (8M0137347)
- 1 x Oil Seal (803752)
- 1 x Seal (8036674)
- 2 x Gaskets (8M0135804, 8M0135806)
Installation Notes
- Disconnect the negative battery cable and remove the upper shift linkage cover.
- Remove the bolts securing the lower unit (gearcase) to the engine.
- Carefully lower the gearcase to access the water pump assembly.
- Unbolt and remove the old water pump housing and all its components.
- Thoroughly clean the driveshaft and all mating surfaces of old gasket material or corrosion.
- Install the new wear plate and gasket onto the gearcase.
- Slide the new impeller onto the driveshaft with the new key, ensuring the vanes are oriented correctly.
- Install the new seals into the new housing and slide the assembly down over the impeller.
- Secure the new housing with the original bolts, torqued to manufacturer specifications.
- Carefully reinstall the lower unit, ensuring the driveshaft, water tube, and shift shaft align properly.
- Reconnect the shift linkage and battery. Start the engine in water and verify a strong tell-tale stream.
Troubleshooting & FAQ
How do I confirm this fits my engine?
Check that your engine is a Mercury 15–20 HP EFI 4-Stroke (2006+) and that its serial number is 0R833820 or higher. The most reliable method is to cross-reference your existing part number with those listed in our Part Number Matrix.
What are the signs of a failing water pump impeller?
Common symptoms include a weak or non-existent water stream from the "telltale" outlet, frequent engine overheating alarms, and a noticeable reduction in engine performance, especially at higher RPMs.
How often should this kit be used for maintenance?
For optimal reliability and to prevent overheating damage, we recommend inspecting the impeller annually and replacing it every 1–2 years or every 100–200 hours of operation, whichever occurs first.
My engine is a 10 HP EFI model. Is this compatible?
While some aftermarket sources suggest compatibility with 10 HP EFI models from the same generation, we advise visually comparing your existing pump components to our product images and part numbers to guarantee a match before purchasing.
Is this an OEM part or an aftermarket equivalent?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, it is batch-inspected for consistency and quality.
What are your shipping speed and costs?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free to most regions; expedited options will appear at checkout where available for your location.
What is the warranty and return policy?
This part is covered by a 1-year warranty against manufacturing defects under normal use. If any issues arise, please contact our support team with your order details. Returns are accepted within our standard window if the item is unused and in its 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 component, not an OEM part.
- Professional installation is recommended for safety and 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 — Enjoy free standard delivery to most regions, with typical transit times of 5–15 days.
- Manufacturer-Direct Value — We deliver fair pricing on high-quality components without compromising on materials or quality control.
Payment & Security
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