Yamaha 4HP/5HP 2-Stroke Water Pump Repair Kit with Housing – Replaces 6E0-W0078-A2-00
Yamaha 4HP/5HP 2-Stroke Water Pump Repair Kit with Housing – Replaces 6E0-W0078-A2-00 is backordered and will ship as soon as it is back in stock.
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Yamaha 4HP/5HP 2-Stroke Water Pump Repair Kit with Housing – Replac...
Yamaha 4HP/5HP 2-Stroke Water Pump Repair Kit with Housing – Replaces 6E0-W0078-A2-00 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket water pump repair kit with housing is designed for selected Yamaha 4HP and 5HP 2-stroke outboards. It provides the principal components required to service the water pump and restore dependable cooling-water circulation when the existing impeller and related pump parts are worn.
The primary Yamaha reference associated with this kit is 6E0-W0078-A2-00. Yamaha parts-catalog occurrences identify this water pump repair kit on selected 4HP and 5HP 2-stroke models, including 1996 4MLHU, 4MLHU2, 4MSHU, 4MSHU2, 5MLHU, 5MLHU2, 5MSHU, and 5MSHU2 applications.
- Water pump repair kit supplied with a pump housing.
- Suitable for selected Yamaha 4HP and 5HP 2-stroke outboards.
- Intended for replacement of worn water-pump service components.
- Verify the exact model, year, and existing part number before ordering.
Part Number References
The following references are catalog or aftermarket identifiers associated with this product family. They should not be treated as universally interchangeable without confirming the engine application.
| Brand | Part Number | Reference Status |
|---|---|---|
| Yamaha | 6E0-W0078-A2-00 | Primary catalog reference |
| Yamaha | 6E0-W0078-A3-00 | Related catalog variant; confirm exact model and year |
| Yamaha | 6E0-W0078-02-00 | Catalog occurrence on selected 1984 applications; not a universal interchange claim |
Important: Sierra 18-3410 is listed in the Sierra catalog as a different Yamaha water-pump kit associated with Yamaha 68T-W0078-00-00. It is not presented here as a confirmed equivalent for this product.
Engine & Model Compatibility
Fitment must be confirmed using the complete engine model and year. Horsepower alone is not sufficient because Yamaha water-pump components can vary by model generation and application.
| Brand | Model Examples | Rated HP | Stroke | Year | Catalog Reference | Notes |
|---|---|---|---|---|---|---|
| Yamaha | 4MLHU, 4MLHU2, 4MSHU, 4MSHU2 | 4 | 2-Stroke | 1996 | 6E0-W0078-A2-00 | Catalog-listed repair-kit applications |
| Yamaha | 5MLHU, 5MLHU2, 5MSHU, 5MSHU2 | 5 | 2-Stroke | 1996 | 6E0-W0078-A2-00 | Catalog-listed repair-kit applications |
| Yamaha | 4MLHV, 4MSHV, 5MLHV, 5MSHV | 4–5 | 2-Stroke | 1997 | 6E0-W0078-A3-00 | Related catalog variant; verify before purchase |
| Yamaha | 4MLHW, 4MSHW, 5MLHW, 5MSHW | 4–5 | 2-Stroke | 1998 | 6E0-W0078-A3-00 | Related catalog variant; verify before purchase |
The available catalog evidence does not confirm fitment for Yamaha F4, F5, or F6 4-stroke engines. Those models have been removed from the confirmed compatibility claims for this listing.
Technical Specs
- Product Type
- Water pump repair kit with housing
- Application
- Selected Yamaha 4HP and 5HP 2-stroke outboards
- Installation
- Direct replacement when the exact engine application is confirmed
- Primary Yamaha Reference
- 6E0-W0078-A2-00
- Construction
- Rubber impeller with metal and molded water-pump service components
- Function
- Restores water-pump service components used for engine cooling
What’s in the Box
This is a water-pump repair kit supplied with a housing. The exact component configuration can vary by application and production version, so compare the supplied parts with the pump assembly on your engine before installation.
- Water-pump impeller
- Water-pump housing and related pump components
- Wear or impeller plate, where specified for the application
- Impeller key, gasket, seals, and installation hardware as applicable to the kit configuration
Installation Notes
- Confirm the complete engine model, year, stroke, and existing water-pump reference before disassembly.
- Stop the engine, remove the ignition key, disconnect the battery where applicable, and allow the engine to cool.
- Place the engine securely in a suitable service position and remove the lower unit according to the manufacturer's service procedure.
- Remove the water-pump housing and inspect the impeller, wear surfaces, key, seals, and mating faces.
- Clean old gasket material and debris from all sealing surfaces.
- Install the replacement components in the same orientation as the removed parts. Make sure the impeller key is fully seated.
- Apply only the lubricant recommended by the engine manufacturer and avoid contaminating gasket or sealing surfaces.
- Reassemble the pump and lower unit using the manufacturer's tightening sequence and torque specifications.
- Run the engine in a suitable test tank or water source and confirm a steady cooling-water telltale stream before normal operation.
Troubleshooting & FAQ
How do I confirm that this kit fits my Yamaha engine?
Compare the complete Yamaha model code and model year with the compatibility information above, and compare the existing water-pump reference with the listed catalog reference. Do not rely on horsepower alone. If the model, year, stroke, or pump design differs, confirm the application before ordering.
What are the signs of a worn water-pump impeller?
Common signs include a weak or interrupted telltale stream, overheating at idle or low speed, reduced cooling-water flow, or a brittle, cracked, melted, or deformed impeller during inspection.
How often should the water-pump components be inspected?
Inspect the water pump at the interval recommended for your engine and whenever the engine has been operated in sandy, silty, weedy, or saltwater conditions. Replace damaged or hardened components promptly.
Does this kit include a housing?
Yes. This listing is described as a water-pump repair kit with housing. Because component configurations can vary by application, compare the product contents with your original pump assembly before installation.
Is this an OEM Yamaha part?
No. This is an aftermarket replacement kit intended for the listed Yamaha applications. Yamaha and other brand names and part numbers are used only to identify compatibility references.
Can I use this kit on a Yamaha F4, F5, or F6 4-stroke?
Fitment for those 4-stroke models is not confirmed by the available catalog evidence for this listing. Confirm the exact engine model and water-pump reference before purchasing.
What if my original part looks different?
Do not install the kit if the housing, impeller, keyway, sealing surfaces, or other critical components differ from your original assembly. Confirm the exact model and application with a qualified marine technician.
Safety & Important Information
- Verify the complete engine model, year, stroke, and existing part number before ordering.
- Do not treat a number appearing in a cross-reference list as proof of universal interchangeability.
- Use the manufacturer's service manual for disassembly, torque, sealing, and testing procedures.
- Professional installation is recommended if you are not experienced with outboard lower-unit or water-pump service.
- This is an aftermarket replacement, not an OEM Yamaha component.
About Sea Sierra
- Marine-Focused Selection — Replacement parts selected for common outboard maintenance and repair applications.
- Application-Conscious Fitment — We recommend checking the complete model and part-number information before ordering.
- Service Support — Clear product information helps you select the correct maintenance component for your engine.
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