Water Pump Repair Kit – Fits Mercury 9.9–20 HP 4-Stroke Outboards (Replaces 8M0135821)

Water Pump Repair Kit – Fits Mercury 9.9–20 HP 4-Stroke Outboards (Replaces 8M0135821)

This water pump repair kit is designed for Mercury 4-Stroke 9.9–20 HP outboard engines with serial numbers 0R833820 and above, including ProKicker and SeaPro models. It provides a direct replacement solution built to meet or exceed original equipment manufacturer specifications.

Replaces the following part numbers: Mercury/Quicksilver 8M0135821, 98-8M0135821, Mercury 8M0137849, and Tohatsu 3RS-87322-1.

• Engineered for a direct fit to the lower unit for straightforward installation.
• Produced to meet Mercury Marine original equipment manufacturer specifications for reliable performance.
• Complete kit includes the essential components for a water pump service: impeller, upper/lower housings, and plate.

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.

Confirm your engine model/year in the table below.

Technical Specifications

Package Contents

• 1 x Water Pump Repair Kit Assembly (Replaces 8M0135821)
• 1 x Water Pump Impeller
• 1 x Upper Housing
• 1 x Lower Housing
• 1 x Plate

Installation Guide

1. Disconnect the battery and shift the outboard into neutral.
2. Remove the propeller and drain the gearcase oil.
3. Unbolt and carefully lower the gearcase from the drive shaft housing.
4. Remove the old water pump housing bolts and lift the housing assembly off.
5. Clean the mounting surfaces and inspect the driveshaft for any wear or damage.
6. Install the new gaskets, plate, and impeller, ensuring the keyway is aligned.
7. Lubricate the inside of the new housing and impeller with grease.
8. Install the new housing, ensuring the impeller vanes are turned in the correct direction (clockwise).
9. Tighten the housing bolts to the manufacturer's specified torque.
10. Re-install the gearcase, making sure the water tube and shift shaft align correctly.
11. Refill the gearcase with fresh oil and re-install the propeller.
12. Reconnect the battery and test the engine in the water, verifying water is exiting the tell-tale port.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my Mercury outboard?

A: This kit is designed for Mercury 4-Stroke 9.9–20 HP outboards with serial numbers 0R833820 and higher. Please use our Mercury Serial Number Guide to verify your engine's serial number before ordering.

Q: What are the signs of a failing water pump?

A: Common signs include a weak or non-existent water stream from the "tell-tale" outlet, engine overheating alarms, or a melted/deformed pump housing upon inspection.

Q: How often should the water pump impeller be replaced?

A: For preventative maintenance, it is recommended to inspect the water pump impeller annually and replace it every 1-2 years or every 100-200 hours of use, depending on operating 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.