Water Pump Repair Kit – Fits Yamaha 20/25 HP 2-Stroke Outboards (Replaces 6L2-W0078-00-00)

Product Details

This Water Pump Repair Kit – Fits Yamaha 20/25 HP 2-Stroke Outboards (Replaces 6L2-W0078-00-00) contains all the necessary components to service and rebuild your water pump. It is designed for Yamaha 2-stroke outboard engines in the 20-25 HP range, ensuring your engine maintains proper cooling and performance.

This kit is a direct interchange for Yamaha part number 6L2-W0078-00-00 and Sierra Marine 18-3431.

• Engineered for Yamaha 20–25 HP two-cylinder 2-stroke outboards.
• Complete kit includes the impeller, cartridge insert, outer plate, O-ring, bolts, and woodruff key.
• Restores cooling system function to prevent overheating and maintain engine reliability.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This kit is designed for a wide range of Yamaha two-cylinder outboards. Please verify your model and year before ordering to ensure a correct fit.

Technical Specs

Product Type

Water Pump Repair Kit

Installation

Outboard Engine

Fuel Type

Gasoline

Housing Material

Metal

Engine Type

2-Stroke

Engine Position

Outboard

Application

Yamaha 20-25 HP Two-Cylinder 2-Stroke Outboards

Warranty

Manufacturer Standard

Package Dimensions

17" L x 16" W x 7" H

What’s in the Box

• 1 x Cartridge Outer Plate (6L2-44323-00-00)
• 1 x O-Ring (93210-45161-00 or 93210-37M67-00)
• 1 x Impeller (6L2-44352-00-00)
• 1 x Cartridge Insert (6L2-44322-00-00)
• 4 x Bolt (97095-06040-00)
• 1 x Woodruff Key (90280-03024-00)

Installation Notes

1. Always disconnect the battery and secure the engine before beginning work.
2. Drain the gearcase lubricant before removing the lower unit from the outboard motor.
3. Carefully unbolt and remove the existing water pump housing.
4. Take note of the old impeller's vane direction before removing it, along with the key, plates, and gaskets.
5. Thoroughly clean all mating surfaces, removing any old gasket material or corrosion.
6. Install the new cartridge insert, outer plate, and O-ring from the kit.
7. Slide the new woodruff key onto the driveshaft and install the new impeller. Rotate the driveshaft in its normal clockwise direction to correctly orient the vanes.
8. Reinstall the water pump housing and tighten the bolts to the manufacturer's specified torque.
9. Reattach the lower unit to the engine and refill the gearcase with fresh lubricant.
10. After reassembly, test the engine in water to confirm a strong, steady stream from the tell-tale outlet.

Troubleshooting & FAQ

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.