Water Pump Repair Kit – Fits Yamaha 9.9HP & 15HP 4-Stroke Outboard Engines (Replaces 63V-W0078-01-00, 63V-W0078-00-00)

Water Pump Repair Kit – Fits Yamaha 9.9HP & 15HP 4-Stroke Outboard Engines

This water pump repair kit is designed for Yamaha 9.9HP and 15HP 4-Stroke outboard engines from 1996 to present, including F15, F9.9, and high-thrust T9.9 models. It provides the necessary components to restore your engine's cooling system for optimal performance and reliability.

This kit serves as a direct aftermarket replacement for Yamaha OEM parts 63V-W0078-01-00 and 63V-W0078-00-00. It also cross-references with Sierra 18-3433, Sierra 18-3412 (with housing), and SeaSierra equivalents.

• Engineered for a direct replacement fit to restore cooling performance.
• Available in two versions: a full kit with housing or a basic kit without housing.
• Restores cooling system function to prevent engine overheating.

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

This kit is available in two versions. Please select the correct version for your needs.

Kit With Housing (Replaces Sierra 18-3412):

• 1 x Impeller (18-3040)
• 1 x Insert Cup (18-3444)
• 1 x Water Pump Housing (18-3356)
• 1 x Impeller Plate (18-3195)
• 1 x Water Seal Damper (18-1833)
• 1 x Impeller Key

Kit Without Housing (Replaces Sierra 18-3433):

• Includes essential components such as the impeller, gaskets, and seals for a repair when the original housing is not damaged. Contents may vary; verify parts against your needs before ordering.

Installation Guide

Professional installation is recommended. The following are general steps and may not be specific to your exact model.

1. Disconnect the spark plug leads and battery cables for safety.
2. Drain the gearcase oil from the lower unit.
3. Unbolt and carefully remove the lower unit (gearcase) from the outboard's midsection.
4. Place the lower unit on a workbench. Unbolt and remove the old water pump housing.
5. Note the orientation of the old parts as you remove the impeller, wear plate, and gaskets.
6. Clean all mating surfaces thoroughly, removing any old gasket material or sealant.
7. Install the new lower gasket, wear plate, and impeller key.
8. Install the new impeller. Turn the driveshaft clockwise while pushing down to seat the vanes correctly.
9. Fit the new insert cup into the housing, and slide the new housing assembly down over the impeller.
10. Apply a light coat of marine-grade grease or soap to the inside of the housing to help seat the impeller.
11. Bolt down the new housing to the specified torque.
12. Reinstall the lower unit, refill with fresh gear lube, and test engine operation in water, ensuring a steady stream from the tell-tale.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my engine?

A: This kit is specifically for Yamaha 9.9HP and 15HP 4-Stroke models from 1996 to present. Please review the "Compatible Engine Models" table and cross-reference your engine's model and year. The kit replaces OEM part numbers 63V-W0078-01-00 and 63V-W0078-00-00.

Q: What is the difference between the kit with housing and the kit without?

A: The full kit (replaces Sierra 18-3412) includes the metal water pump housing. The basic kit (replaces Sierra 18-3433) does not. You only need the basic kit if your existing housing is in good condition, free of cracks, corrosion, or warping.

Q: How often should I replace my water pump impeller?

A: For preventative maintenance, it is recommended to inspect the impeller annually and replace it every 1-2 years or every 100-200 hours of operation, whichever comes first. Service intervals should be shorter for engines used in saltwater or sandy/silty conditions.

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

A: The most common signs include the engine overheating at idle or low speeds, or a weak or non-existent water stream from the "tell-tale" outlet port. A brittle, cracked, or deformed impeller found during an inspection also indicates an immediate need for replacement.

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.