Water Pump Repair Kit Without Housing – Fits Yamaha 2-Stroke 25–30 HP 3-Cylinder Outboards (Replaces 6J8-W0078-A1-00 and 6J8-W0078-A2-00)
Water Pump Repair Kit Without Housing – Fits Yamaha 2-Stroke 25–30 HP 3-Cylinder Outboards (Replaces 6J8-W0078-A1-00 and 6J8-W0078-A2-00) is backordered and will ship as soon as it is back in stock.
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Water Pump Repair Kit Without Housing – Fits Yamaha 2-Stroke 25–30 ...
Water Pump Repair Kit Without Housing – Fits Yamaha 2-Stroke 25–30 HP 3-Cylinder Outboards (Replaces 6J8-W0078-A1-00 and 6J8-W0078-A2-00) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Repair Kit Without Housing is an aftermarket water pump service kit for selected Yamaha 2-stroke 25 HP and 30 HP three-cylinder outboards. It is intended to refresh the water pump assembly and help restore reliable cooling-system performance during routine service or repair.
The kit is supplied without the water pump housing. Confirm the engine's horsepower, cylinder configuration, stroke, year range, and existing OEM reference before ordering.
- For selected Yamaha 2-stroke 25 HP and 30 HP three-cylinder outboards.
- Service-kit configuration supplied without the water pump housing.
- Includes the pump-service components specified for this application, including the impeller, gaskets, plates, cartridge components, and hardware.
- Designed as an aftermarket replacement for the applicable water pump repair kit references.
Part Number Matrix
Use the references below together with your engine model and year to help confirm compatibility.
| Brand or Supplier | Part Number | Reference Type |
|---|---|---|
| Yamaha | 6J8-W0078-A1-00 | OEM reference |
| Yamaha | 6J8-W0078-A2-00 | OEM reference |
| Aftermarket | 18-3430 | Aftermarket reference |
Engine & Model Compatibility
The company fitment record identifies the following application scope. Model-specific fitment can vary, so match all available engine-identification details before installation.
| Brand | Horsepower | Stroke | Cylinder Configuration | Year Range | OEM Reference |
|---|---|---|---|---|---|
| Yamaha | 25 HP or 30 HP | 2-Stroke | 3-Cylinder | 1996–2002 | 6J8-W0078-A2-00 |
| Yamaha | 30 HP | 2-Stroke | 3-Cylinder | 1982–1995 | 6J8-W0078-A1-00 |
Technical Specs
- Product Type
- Water pump repair kit
- Housing
- Not included; service kit is supplied without the water pump housing
- Application
- Selected Yamaha 2-stroke 25 HP and 30 HP three-cylinder outboards
- Replacement Type
- Aftermarket replacement
What’s in the Box
This is a water pump service kit supplied without the water pump housing. The kit includes the service components listed for this application:
- 1 x Cartridge insert
- 1 x Water pump impeller
- Water pump gaskets
- 1 x Cartridge outer plate
- 1 x Cartridge gasket
- Bolts with washers
The existing water pump housing is not included and must be reused if it is serviceable or replaced separately when required.
Installation Notes
- Disconnect the battery and shift linkage before beginning work, following the engine service manual.
- Remove the lower-unit mounting bolts and carefully lower the gearcase from the engine.
- Unbolt and remove the water pump housing to access the impeller and service components.
- Remove the old impeller, plates, and gaskets. Note the orientation of the impeller vanes before removal.
- Clean all mating surfaces thoroughly and remove old gasket material, debris, and corrosion.
- Inspect the reusable water pump housing for scoring, distortion, corrosion, or excessive wear before reassembly.
- Install the replacement cartridge components, plates, gaskets, and impeller from the kit in the order specified by the service manual.
- Slide the impeller onto the driveshaft and rotate it in the direction of engine operation while seating the housing.
- Apply only the lubricant or sealant recommended by the service manual and tighten fasteners to the manufacturer's specifications.
- Reinstall the lower unit, align the driveshaft, water tube, and shift shaft, reconnect the linkage, and test the cooling-water flow using an appropriate water supply.
Troubleshooting & FAQ
How do I know if this kit fits my Yamaha outboard?
Confirm that your engine is a Yamaha 2-stroke 25 HP or 30 HP three-cylinder model within the applicable year range: 25 HP or 30 HP models from 1996–2002, or 30 HP models from 1982–1995. Also compare the existing water pump repair kit reference with 6J8-W0078-A1-00 or 6J8-W0078-A2-00.
Does this kit include the water pump housing?
No. This product is a water pump repair kit supplied without the water pump housing. Inspect your existing housing and reuse it only if it remains within serviceable condition.
What are common signs that a water pump needs service?
A weak or missing telltale stream, overheating, reduced cooling-water flow, or an impeller with cracked, brittle, or damaged vanes can indicate that the water pump requires inspection and service.
Can I install the kit without replacing the housing?
Yes, when the existing housing is compatible and serviceable. Check it for scoring, corrosion, distortion, and wear before installation. A damaged housing should be replaced separately.
Is this an OEM component?
No. This listing is for an aftermarket replacement water pump repair kit. Yamaha part numbers are provided only as OEM reference numbers for compatibility identification.
How often should the water pump be serviced?
Inspect and service the water pump according to the engine manufacturer's maintenance schedule and whenever cooling-water flow is reduced. Service may be needed more frequently in saltwater, silty, or debris-filled operating conditions.
Safety & Important Info
- Verify the complete engine model, horsepower, stroke, cylinder configuration, year, and OEM reference before ordering.
- The water pump housing is not included.
- Do not operate an outboard with inadequate cooling-water flow.
- Follow the manufacturer's service manual for disassembly, torque values, lubrication, sealant, and testing procedures.
- Professional installation is recommended when lower-unit service experience or the correct service documentation is not available.
About Sea Sierra
- Marine Replacement Parts — Practical aftermarket components for routine marine maintenance and repair.
- Application-Focused Fitment — Product references and engine conditions are provided to support compatibility checks.
- Service-Ready Solutions — Replacement parts designed to help restore dependable marine-system performance.
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