Water Pump Repair Kit – Yamaha 4 HP & 5 HP 2-Stroke Outboards (Selected 1984–2002 Models)
Water Pump Repair Kit – Yamaha 4 HP & 5 HP 2-Stroke Outboards (Selected 1984–2002 Models) is backordered and will ship as soon as it is back in stock.
Worry-free returns
Worry-free returns
Shop with confidence. If you’re not completely satisfied, eligible items may be returned within the return window, provided they are unused and in original packaging.
If the return is due to our error or a defective item, we’ll make it right.
Please contact us before returning any item.
Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Water Pump Repair Kit – Yamaha 4 HP & 5 HP 2-Stroke Outboards (...
Water Pump Repair Kit – Yamaha 4 HP & 5 HP 2-Stroke Outboards (Selected 1984–2002 Models) is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket water pump repair kit is designed for selected Yamaha 4 HP and 5 HP 2-stroke outboards. It is listed in engine parts catalogs as a water pump repair kit for specific Yamaha models and model years from 1984 through 2002. Confirm the exact model, year, and existing water pump part number before ordering.
The kit is associated with Yamaha water pump repair kit references including 6E0-W0078-02-00 for selected 1984–1985 models, 6E0-W0078-A2-00 for selected 1996 models, and 6E0-W0078-A3-00 for selected 1997–2002 models. These references apply only to the model and year combinations shown below; a shared part number does not confirm fitment for every 4 HP or 5 HP outboard.
- Replacement water pump repair kit for selected Yamaha 4 HP and 5 HP 2-stroke outboards.
- Designed for water pump service and restoration of proper cooling-water circulation.
- Use the existing parts and the engine service information to confirm installation orientation and required hardware.
Part Number Matrix
The following references are documented for the specific Yamaha applications listed in the compatibility table. They should not be treated as universal equivalents outside those applications.
| Brand | Water Pump Repair Kit Reference | Documented Application Scope |
|---|---|---|
| Yamaha | 6E0-W0078-02-00 | Selected 1984–1985 Yamaha 4 HP and 5 HP 2-stroke models |
| Yamaha | 6E0-W0078-A2-00 | Selected 1996 Yamaha 4 HP and 5 HP 2-stroke models |
| Yamaha | 6E0-W0078-A3-00 | Selected 1997–2002 Yamaha 4 HP and 5 HP 2-stroke models |
Engine & Model Compatibility
Fitment is limited to the documented Yamaha 2-stroke applications below. Model suffixes, year, and stroke must all match. Always compare the part number on the original water pump kit with the applicable reference before purchase.
| Brand | Model Examples | Rated HP | Stroke | Years | Applicable Reference |
|---|---|---|---|---|---|
| Yamaha | 4LK, 4LN, 4SK, 4SN | 4 | 2-Stroke | 1984–1985 | 6E0-W0078-02-00 |
| Yamaha | 5LK, 5LN, 5SK, 5SN | 5 | 2-Stroke | 1984–1985 | 6E0-W0078-02-00 |
| Yamaha | 4MLHU, 4MLHU2, 4MSHU, 4MSHU2 | 4 | 2-Stroke | 1996 | 6E0-W0078-A2-00 |
| Yamaha | 5MLHU, 5MLHU2, 5MSHU, 5MSHU2 | 5 | 2-Stroke | 1996 | 6E0-W0078-A2-00 |
| Yamaha | 4MLHV, 4MSHV, 4MLHW, 4MSHW, 4MLHX, 4MSHX | 4 | 2-Stroke | 1997–1999 | 6E0-W0078-A3-00 |
| Yamaha | 5MLHV, 5MSHV, 5MLHW, 5MSHW, 5MLHX, 5MSHX | 5 | 2-Stroke | 1997–1999 | 6E0-W0078-A3-00 |
| Yamaha | 5MLHY, 5MSHY, 5MSHKZ, 5MSHZ, 5MSHA | 5 | 2-Stroke | 2000–2002 | 6E0-W0078-A3-00 |
Not confirmed: Yamaha 4-stroke F4 models and Mariner models are not included in the verified application scope for this listing. Do not use the kit for those engines unless the exact engine catalog and part number independently confirm compatibility.
Technical Specifications
- Product Type
- Water pump repair kit
- Application
- Selected Yamaha 4 HP and 5 HP 2-stroke outboards
- Installation
- Replacement water pump service component
- Aftermarket Status
- Aftermarket replacement; not manufactured by Yamaha
What’s in the Box
This listing is supplied as a water pump repair kit. The kit is intended to replace the water pump service components shown in the product imagery and associated application listing. Component configuration may vary by production batch; compare the supplied parts with the original assembly before installation.
- Water pump repair components for the applicable Yamaha lower unit
- Impeller and related water pump service components as applicable to the kit configuration
- Gaskets, seals, plates, insert, dowel pin, and fasteners where included in the illustrated kit configuration
Do not assume that every component listed for a Yamaha OEM assembly is included unless it is visible in the package or specifically identified by the seller.
Installation Notes
- Disconnect the spark plug wire and secure the engine against accidental starting. Follow the service manual for your exact model.
- Remove the lower unit according to the engine manufacturer's procedure, taking care not to damage the shift shaft, driveshaft, or water tube.
- Remove the existing water pump components and note the orientation of the impeller vanes, gasket, plate, and water pump housing.
- Clean all mating surfaces and inspect the driveshaft, keyway, water tube, and lower-unit sealing surfaces before assembly.
- Install the replacement gasket, plate, impeller, key or dowel, and housing components in the same arrangement as the original assembly and service-manual diagram.
- Rotate the driveshaft in the specified direction while seating the impeller so the vanes fold correctly inside the housing.
- Install and tighten the water pump fasteners to the torque specification for the exact engine model.
- Reinstall the lower unit, confirming correct alignment of the driveshaft, shift shaft, and water tube.
- Run the engine in an appropriate test tank or in the water and confirm a strong, continuous cooling-water discharge before normal operation.
Maintenance & FAQ
How do I know if the water pump needs service?
Common warning signs include weak or absent cooling-water discharge, overheating, an engine temperature alarm, or an impeller that is cracked, brittle, deformed, or damaged. Inspect the complete water pump assembly if cooling performance changes.
Will this kit fit every Yamaha 4 HP or 5 HP outboard?
No. Fitment is limited to the Yamaha 2-stroke model and year combinations documented in the compatibility table. Horsepower alone is not sufficient to confirm fitment because water pump designs and part references can vary by model suffix and year.
Does this kit fit Yamaha F4 four-stroke engines?
Four-stroke F4 fitment is not confirmed for this listing. Use the exact four-stroke engine model and serial information to identify the correct water pump kit.
Does this kit fit Mariner 4 HP or 5 HP outboards?
Mariner fitment is not confirmed for this listing. Do not order based only on horsepower or a similar-looking engine; verify the exact Mariner model, year, serial range, and water pump reference first.
Is this an OEM Yamaha part?
No. This is an aftermarket replacement water pump repair kit. Yamaha and the listed Yamaha part references are used only to identify the documented application and replacement reference.
How often should the impeller be replaced?
Inspect the impeller and water pump during scheduled service and replace them when wear, cracking, hardening, deformation, or reduced cooling-water flow is found. Operating conditions such as saltwater, sand, or silt may require more frequent inspection.
Safety & Important Information
- Verify the complete engine model, year, stroke, and part number before ordering.
- Do not rely on horsepower alone to determine compatibility.
- Use the service manual for the exact engine when removing or installing the lower unit and water pump.
- Do not operate the engine if the cooling-water discharge is weak or absent.
- Professional installation is recommended when lower-unit or water-pump service procedures are unfamiliar.
About Sea Sierra
- Replacement marine parts for routine maintenance and repair.
- Application-focused listings with model and part-number information where available.
- Support for selecting replacement components based on the engine's exact specifications.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
