Water Pump Repair Kit – Fits Yamaha F40/F70 4-Stroke Outboards (Replaces 6CJ-W0078-00-00, 6CJ-W0078-01-00)

Water Pump Repair Kit – Fits Yamaha F40/F70 4-Stroke Outboards

This comprehensive water pump repair kit provides all necessary components to service the lower unit water pump on Yamaha F40 and F70 4-stroke outboards (2011–2016). It is engineered to meet or exceed original equipment specifications for reliable performance.

This kit is a direct replacement for Yamaha part numbers 6CJ-W0078-00-00 and 6CJ-W0078-01-00, as well as Sierra 18-3494 and Quicksilver 8M6012800 (for F70 applications).

• Includes all required gaskets, seals, impeller, and hardware for a complete rebuild.
• Restores cooling system performance to prevent overheating.
• Designed for installation in the lower unit.

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 Yamaha owners, here’s a guide to help you identify your engine’s serial/model: Yamaha Serial Number Guide. You can also review exploded diagrams to verify part numbers: Yamaha Parts Diagrams & Catalog.

Technical Specifications

Package Contents

• 1 x Insert, Cartridge (63D-44322-00-00)
• 1 x Gasket, Water Pump (6CJ-44315-00-00)
• 1 x Cover, Pump Housing (63D-44312-00-00)
• 1 x Damper, Water Seal 2 (663-44366-00-00 / 663-44366-01-00)
• 1 x Impeller (6H3-44352-00-00 / 6H4-44352-02-00)
• 1 x Key, Woodruff (90280-03M03-00)
• 2 x Oil Seal (93101-23070-00)
• 1 x O-Ring (93210-46044-00 / 93210-59MG7-00)
• 1 x Gasket, Water Pump (6CJ-44316-00-00 / 63D-44316-00-00)
• 1 x Outer Plate, Cartridge (6CJ-44323-00-00 / 63D-44323-00-00)
• 1 x Gasket, Cartridge (6CJ-44324-00-00)
• 2 x Pin, Dowel (93604-10M03-00)
• 2 x Bolt, With Washer (90119-08M33-00)
• 2 x Bolt, With Washer (90119-08M14-00 / 90119-08M15-00)

Installation Guide

1. Disconnect the negative battery cable and shift the outboard into the neutral position.
2. Remove the bolts securing the lower unit (gearcase) to the upper driveshaft housing.
3. Carefully lower and separate the lower unit from the engine. Be mindful of the shift shaft linkage.
4. Unscrew the bolts on the water pump housing and remove the cover.
5. Slide the old impeller off the driveshaft, and remove the Woodruff key, gaskets, and wear plates. Note their orientation.
6. Thoroughly clean all mating surfaces, removing any old gasket material or sealant.
7. Install the new cartridge insert and outer plate from the kit, followed by the new gaskets.
8. Slide the new Woodruff key into its slot on the driveshaft and install the new impeller. Rotate the driveshaft clockwise to bend the vanes correctly.
9. Install the new O-ring, seals, and housing cover, then tighten the bolts to the manufacturer's specified torque.
10. Apply marine grease to the driveshaft splines and reinstall the lower unit, ensuring the water tube and shift shaft align correctly.
11. Securely fasten the lower unit bolts.
12. Reconnect the battery, supply water to the engine using flushing muffs, and run it to confirm proper water flow from the tell-tale outlet.

Troubleshooting & FAQ

How do I confirm this kit fits my Yamaha engine?

This kit is designed for Yamaha F40 and F70 4-stroke outboards from 2011 to 2016. To ensure a correct fit, check the "Compatible Engine Models" table to verify your specific model and year. You should also cross-reference your existing part number with those listed in our guide (e.g., Yamaha 6CJ-W0078-00-00, Sierra 18-3494) to confirm compatibility.

What are the signs my water pump needs to be replaced?

Common signs of a failing water pump include the engine overheating, a weak or non-existent "telltale" water stream from the outlet, or a visibly cracked, brittle, or damaged impeller found during a routine inspection.

How often should I replace my outboard's water pump impeller?

For preventative maintenance, it is recommended to inspect and replace the water pump impeller and related components every 100-200 operating hours or at least once per boating season. Replacement intervals should be shorter if you frequently operate in sandy, silty, or saltwater conditions.

OEM vs. Aftermarket?

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.

How fast do you ship and how much does it cost?

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.

What is your warranty and return policy?

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.