Water Pump Impeller Repair Kit – Fits Mercury Marine 15-20 HP EFI Outboard (Replaces 8M0135821, 46-8M0135821)

Water Pump Impeller Repair Kit – Fits Mercury Marine 15-20 HP EFI Outboard (Replaces 8M0135821, 46-8M0135821)

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. It covers standard, SeaPro, and ProKicker models, ensuring your engine's cooling system functions reliably.

It serves as a direct replacement for multiple OEM and aftermarket parts, providing a comprehensive solution for maintenance and repair.

• Complete Repair Kit: Includes all necessary components for a full water pump service, including the impeller, housing, plate, gaskets, and seals.
• Direct Replacement: Engineered to meet or exceed OEM specifications for fit and performance, replacing Mercury parts 8M0135821 and 46-8M0135821.
• Critical Maintenance: Restores cooling system performance to prevent engine overheating and damage.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

This kit includes the following components:

• 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 Guide

Professional installation is recommended. The following is a general guide:

1. Disconnect the battery and remove the engine cover.
2. Place the outboard in neutral gear.
3. Remove the bolts securing the lower unit (gearcase) to the upper driveshaft housing.
4. Carefully lower the gearcase to expose the water pump assembly. You may need to disconnect the shift shaft.
5. Unbolt and remove the old water pump housing and its components. Note the orientation of all parts.
6. Clean the mounting surfaces and driveshaft.
7. Install the new wear plate, gaskets, and impeller key.
8. Slide the new impeller onto the driveshaft, turning it in the correct rotational direction.
9. Install the new insert cup and housing, followed by the new seals.
10. Re-install the water pump assembly, ensuring all bolts are torqued to manufacturer specifications.
11. Re-attach the lower unit to the outboard, aligning the driveshaft, water tube, and shift shaft.
12. Once assembled, test the engine using a water source (flusher or test tank) to confirm proper cooling system operation.

Troubleshooting & FAQ

Q: How do I confirm this kit will fit my engine?
A: This kit is designed for Mercury 15-20 HP EFI 4-Stroke models from 2006-Present with a serial number of 0R833820 or higher. Please verify your engine's model, year, and serial number against the compatibility table. For 10 HP models, some sources suggest compatibility, but we recommend checking your specific part number before ordering.

Q: What are the symptoms of a failing water pump impeller?
A: Common signs include the engine running hotter than normal, an engine overheat alarm, or a weak or inconsistent stream of water from the "tell-tale" outlet. Reduced cooling performance can cause severe engine damage.

Q: How often should the water pump impeller and kit be replaced?
A: For preventative maintenance, it is recommended to inspect the impeller annually and replace the entire water pump kit every 1-2 years or every 100-200 hours of operation, depending on usage conditions (e.g., saltwater vs. freshwater).

Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.