Water Pump Repair Kit – Fits Yamaha 150–300 HP Outboards and Mercury 225 EFI (OEM 61A-W0078-A2/A3, 888687A1)
Water Pump Repair Kit – Fits Yamaha 150–300 HP Outboards and Mercury 225 EFI (OEM 61A-W0078-A2/A3, 888687A1) is backordered and will ship as soon as it is back in stock.
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Water Pump Repair Kit – Fits Yamaha 150–300 HP Outboards and Mercur...
Water Pump Repair Kit – Fits Yamaha 150–300 HP Outboards and Mercury 225 EFI (OEM 61A-W0078-A2/A3, 888687A1) is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket water pump repair kit is intended to restore the cooling-water pump on selected Yamaha outboard engines and the Mercury Mariner 225 EFI four-stroke application listed below. The Yamaha configuration is supplied as a kit with the water-pump housing and is associated with Yamaha OEM references 61A-W0078-A2-00 and 61A-W0078-A3-00. The Mercury application is associated with OEM reference 888687A1.
Use the engine model, horsepower, stroke, year, and serial-number conditions together when checking fitment. A part-number match by itself does not confirm compatibility with every engine in the same horsepower range.
- Designed for water-pump service and cooling-system restoration.
- Yamaha 2-stroke applications include the pump housing configuration listed by the manufacturer.
- Includes the water-pump service components required for the applicable configuration; compare the original assembly before installation.
- Aftermarket replacement part; not manufactured or branded by Yamaha or Mercury Marine.
Part Number References
The following references are associated with the applications covered by this listing. They are manufacturer or aftermarket catalog numbers, not the seller's internal identifier.
| Brand | Reference | Application or relationship |
|---|---|---|
| Yamaha | 61A-W0078-A2-00 | Water pump repair kit reference for selected 2-stroke applications |
| Yamaha | 61A-W0078-A3-00 | Water pump repair kit reference for selected 2-stroke applications |
| Sierra | 18-3396-1 | Aftermarket water pump kit reference associated with the Yamaha application |
| Mercury Mariner | 888687A1 | Water pump repair kit reference for 225 EFI four-stroke engines with serial number 0T653945 and up |
Engine & Model Compatibility
Confirm the complete engine identification before ordering. The Yamaha fitment below is grouped by stroke and model conditions; the Mercury fitment is listed separately because it uses a different engine family and OEM reference.
| Brand | Model or model group | Rated HP | Stroke | Year or serial condition | Reference |
|---|---|---|---|---|---|
| Yamaha | P150 | 150 | 2-Stroke | 1992–1996 | 61A-W0078-A2/A3 |
| Yamaha | P175 | 175 | 2-Stroke | 1994–1996 | 61A-W0078-A2/A3 |
| Yamaha | P200 | 200 | 2-Stroke | 1991–1996 | 61A-W0078-A2/A3 |
| Yamaha | C150 | 150 | 2-Stroke | 1996; selected 1997–1999 models | 61A-W0078-A2/A3 |
| Yamaha | L150–L250 | 150–250 | 2-Stroke | 1996 | 61A-W0078-A2/A3 |
| Yamaha | S150–S250 | 150–250 | 2-Stroke | 1996 | 61A-W0078-A2/A3 |
| Yamaha | 225 and 250 | 225–250 | 2-Stroke | 1992–2023 as listed; verify exact model | 61A-W0078-A2/A3 |
| Yamaha | S150, SX150, S200, SX200, S250, SX250, V150–V250, VX150–VX250, VZ150–VZ200 (2.6L), Z150–Z300, P150–P200, C150 | 150–300 | 2-Stroke | 1997–1999 | 61A-W0078-A2/A3 |
| Yamaha | PX150 | 150 | 2-Stroke | 1999 | 61A-W0078-A2/A3 |
| Yamaha | F150, F200, F225 | 150–225 | 4-Stroke | As listed in the company fitment record; verify exact model and serial number | 61A-W0078-A2/A3 |
| Mercury Mariner | 225 EFI | 225 | 4-Stroke | USA serial number 0T653945 and up | 888687A1 |
Technical Specifications
- Product Type
- Water pump repair kit
- Yamaha Configuration
- Kit with water-pump housing for the listed Yamaha applications
- Yamaha Stroke Coverage
- Selected 2-stroke applications; selected 4-stroke F150, F200, and F225 applications are also listed
- Mercury Configuration
- Selected 225 EFI four-stroke application, serial number 0T653945 and up
- Primary Yamaha References
- 61A-W0078-A2-00 and 61A-W0078-A3-00
- Mercury Reference
- 888687A1
- Aftermarket Reference
- Sierra 18-3396-1
- Brand Status
- Aftermarket replacement
Kit Contents
The Yamaha company records describe this product as a water-pump service kit with housing. Catalog information for the associated Yamaha kit configuration identifies service components such as a water-pump impeller, housing, impeller key, gaskets, wear plate or insert, O-rings, dowel pins, washers, and fasteners. Component style and quantity can vary by engine application, so compare the supplied parts with the original water-pump assembly before installation.
- Water-pump service kit for the applicable engine configuration
- Water-pump housing for the listed Yamaha with-housing configuration
- Impeller and associated sealing and mounting components as applicable to the selected application
Installation Notes
- Confirm the engine model, stroke, year, and serial number before beginning service.
- Disconnect the battery and follow the engine manufacturer's service procedure.
- Remove the lower unit and access the water-pump assembly according to the service manual for the specific engine.
- Remove the old housing, impeller, key, gaskets, seals, and related service components.
- Clean all mating surfaces and inspect the driveshaft, water-pump base, insert, and wear surfaces for damage.
- Install the new components in the correct order using the manufacturer's torque specifications.
- Orient the impeller correctly and lubricate it with a suitable water-based lubricant before fitting the pump housing.
- Reinstall the lower unit, reconnect the battery, and test for proper cooling-water flow before normal operation.
Troubleshooting & FAQ
What engines does this kit fit?
It fits selected Yamaha 150–300 HP outboards, including the Yamaha model groups and year ranges shown above, plus the listed Yamaha F150, F200, and F225 applications. It also covers the Mercury Mariner 225 EFI four-stroke application with USA serial number 0T653945 and up. Verify the complete engine identification before ordering.
Does the Yamaha version include the water-pump housing?
Yes. The company records matching this product describe the Yamaha service-kit configuration as including the water-pump housing. Confirm that the housing and other supplied components match your original assembly before installation.
Is this an OEM Yamaha or Mercury part?
No. This is an aftermarket replacement kit that references the listed Yamaha, Sierra, and Mercury part numbers for identification and fitment.
When should a water-pump kit be replaced?
Inspect the water-pump assembly during scheduled maintenance and whenever cooling-water flow is weak, the engine overheats, or the telltale stream is reduced. Follow the maintenance interval and inspection procedure specified for your engine.
Why must I check the serial number?
Water-pump designs can change between model years, strokes, shaft configurations, and serial-number ranges. The Mercury application listed here specifically requires USA serial number 0T653945 and up, while Yamaha fitment is separated by model and year conditions.
Safety & Important Information
- Verify the exact engine model, year, stroke, horsepower, and serial number before purchase.
- Do not rely on horsepower alone to determine compatibility.
- Compare the original water-pump housing, impeller, key, gaskets, and sealing components with the replacement kit.
- Use the engine service manual for torque values, lower-unit removal, and installation procedures.
- Professional installation is recommended when the correct service procedure or fitment is uncertain.
About Sea Sierra
- Marine Replacement Parts — We provide aftermarket service components for marine engines and cooling systems.
- Application-Focused Fitment — Product information is organized around engine model, year, stroke, horsepower, and serial-number conditions.
- Service-Ready Selection — Our listings are intended to help you identify the correct replacement components for routine marine maintenance.
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