Water Pump Repair Kit with Housing for Yamaha 2-Stroke 40–55 HP Outboards – 6H4 Code
Water Pump Repair Kit with Housing for Yamaha 2-Stroke 40–55 HP Outboards – 6H4 Code is backordered and will ship as soon as it is back in stock.
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Water Pump Repair Kit with Housing for Yamaha 2-Stroke 40–55 HP Out...
Water Pump Repair Kit with Housing for Yamaha 2-Stroke 40–55 HP Outboards – 6H4 Code is backordered and will ship as soon as it is back in stock.
Product Details
This water pump repair kit includes the water pump housing and is designed for selected Yamaha 2-stroke outboards using the 6H4 code. It is intended for servicing the complete water pump assembly and includes the primary components needed for a water pump replacement.
The company application data identifies this product for Yamaha 2-stroke 40–55 HP outboards, including 40 HP, 48 HP, 50 HP, and 55 HP applications listed below. Confirm the exact engine model, year, and 6H4 code before ordering.
- Water pump service kit with housing included.
- Designed for selected Yamaha 2-stroke 6H4-code outboards.
- Suitable for replacing worn or damaged water pump service components.
- Reference application: Yamaha OEM number 6H4-W0078-00 with housing.
Part Number References
The following numbers are reference listings associated with this water pump application. They are provided for identification and interchange research only; always compare the original assembly and engine details before purchase.
| Brand or Source | Reference Number | Notes |
|---|---|---|
| Yamaha | 6H4-W0078-00 | Company reference; housing included |
| Yamaha | 6H4-W0078-00-00 | Catalog reference for the 6H4 water pump repair kit |
| Yamaha | 6H4-W0078-A0-00 | Catalog reference associated with the same application family |
| Sierra | 18-3429 | Aftermarket water pump kit reference |
Engine & Model Compatibility
Fitment is limited to Yamaha 2-stroke outboards using the 6H4 code. The horsepower and year ranges below come from the company application data.
| Brand | Rated HP | Stroke | Years | Engine Code | Application Notes |
|---|---|---|---|---|---|
| Yamaha | 40 | 2-Stroke | 1984–1987 | 6H4 | Selected 40 HP applications |
| Yamaha | 40 | 2-Stroke | 1992–1994 | 6H4 | Selected 40 HP applications |
| Yamaha | 48 | 2-Stroke | 1995–2000 | 6H4 | Selected 48 HP applications |
| Yamaha | 50 | 2-Stroke | 1984–1987 | 6H4 | Selected 50 HP applications |
| Yamaha | 50 | 2-Stroke | 1992–1994 | 6H4 | Selected 50 HP applications |
| Yamaha | 55 | 2-Stroke | 1989–1995 | 6H4 | Selected 55 HP applications |
Technical Specifications
- Product Type
- Water pump repair kit with housing
- Application
- Selected Yamaha 2-stroke outboards with the 6H4 code
- Horsepower Range
- 40–55 HP, including listed 40 HP, 48 HP, 50 HP, and 55 HP applications
- Housing
- Included
- Installation
- Replacement water pump service installation; verify the exact engine application before fitting
What’s in the Box
This product is sold as a water pump service kit with the housing included. The kit is intended to replace the water pump assembly components required for the stated application. Exact component styles and hardware may vary by engine model and production version, so compare the supplied parts with the original assembly before installation.
- Water pump housing
- Water pump impeller
- Water pump service gaskets and wear components
- Installation hardware and related water pump service parts for the applicable 6H4 assembly
Installation Notes
- Confirm the outboard model, year, horsepower, 6H4 code, and original water pump configuration before beginning work.
- Disconnect the battery and place the outboard in neutral.
- Remove the lower unit according to the manufacturer's service procedure, supporting it securely during removal.
- Remove the existing water pump housing and inspect the driveshaft, keyway, water tube, and mating surfaces.
- Clean away old gasket material and debris without damaging the sealing surfaces.
- Install the new water pump service components and housing in the correct order for the specific engine model.
- Install the impeller with the vanes oriented in the correct direction for driveshaft rotation.
- Reassemble the water pump and lower unit using the manufacturer's specified tightening sequence and torque values.
- Reconnect the shift linkage and water tube, then verify that the lower unit is securely mounted.
- Run the engine using the correct water supply procedure and confirm a strong cooling-water tell-tale stream before normal operation.
Maintenance & Troubleshooting
Inspect the water pump whenever the engine shows overheating symptoms, reduced tell-tale flow, or signs of cooling-system restriction. Replace the impeller and related service components when they are cracked, brittle, deformed, or excessively worn. Maintenance intervals depend on operating hours, storage conditions, and exposure to salt, sand, or silt.
How do I confirm that this kit fits my engine?
Check the engine model, year, horsepower, and 6H4 code against the compatibility table. Do not rely on horsepower alone because Yamaha applications can vary by model and production year.
Does this product include the water pump housing?
Yes. The company product record identifies this water pump service kit as a housing-included version.
What are common signs of a failing water pump?
Possible signs include overheating, weak or missing tell-tale flow, reduced cooling-water circulation, and visible impeller damage during inspection.
Why might the engine still overheat after installation?
Check impeller orientation, gasket alignment, water-tube engagement, intake passages, the tell-tale outlet, thermostat, and other cooling-system components. If the problem continues, stop operating the engine and have it inspected by a qualified marine technician.
Is this an OEM Yamaha part?
This listing is for a replacement water pump service kit. Yamaha and aftermarket numbers are shown only as reference numbers; the product should not be represented as a genuine Yamaha-manufactured part.
Safety & Important Information
- Verify the complete engine model and 6H4 application before ordering.
- Compare the original housing, impeller, gaskets, key, and mounting hardware with the supplied parts before installation.
- Follow the manufacturer's service manual for removal, installation, torque values, lubrication, and testing.
- Do not operate an outboard that is overheating or not producing a normal cooling-water tell-tale stream.
- Professional installation is recommended when the correct application or installation procedure is uncertain.
About Sea Sierra
- Marine Replacement Parts — Replacement components for common outboard maintenance and repair applications.
- Application-Focused Listings — Product information is organized around engine model, horsepower, year, and part-number references.
- Support for Routine Service — Practical parts information to help customers identify the correct maintenance component before ordering.
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