Aftermarket Water Pump Impeller for Nissan/Tohatsu 2–6 HP Outboards and Mercury 2–3.5 HP 4-Stroke Models
Aftermarket Water Pump Impeller for Nissan/Tohatsu 2–6 HP Outboards and Mercury 2–3.5 HP 4-Stroke Models is backordered and will ship as soon as it is back in stock.
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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.
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Aftermarket Water Pump Impeller for Nissan/Tohatsu 2–6 HP Outboards...
Aftermarket Water Pump Impeller for Nissan/Tohatsu 2–6 HP Outboards and Mercury 2–3.5 HP 4-Stroke Models is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket water pump impeller is designed for selected small Nissan/Tohatsu and Mercury/Mariner outboard applications. It supports Nissan 3.5B/NS5B engines, Tohatsu 2-stroke 2 HP, 2.5 HP, 2.5A, 3.5A, 3.5B, 3.5 HP, 4 HP, and 5 HP models, as well as Tohatsu 4-stroke MFS4, MFS5, and MFS6 HP models. The company fitment information also identifies Mercury/Mariner 4-stroke 2 HP, 2.5 HP, and 3.5 HP carbureted applications.
The impeller is a direct replacement component for water pump service when its dimensions and original part reference match your engine. Catalog records also associate the primary Tohatsu reference with selected M2/M2.5/M3.5, M4/M5, MFS2/MFS2.5/MFS3.5, and MFS4/MFS5/MFS6 engine applications. Always confirm the exact model and service information before installation.
- Single aftermarket water pump impeller.
- Six-blade design for the listed outboard applications.
- Inside diameter: 10.25 mm.
- Outside diameter: 33.6 mm.
- Width: 14.2 mm.
Part Number Matrix
The following OEM and aftermarket references are associated with this impeller. A reference number alone does not replace confirmation of the complete engine model and application.
| Brand or Supplier | Reference Number | Reference Type |
|---|---|---|
| Tohatsu | 369-65021-1 | OEM reference |
| Tohatsu | 369650211M | OEM reference format |
| Mercury Marine | 47-16154-3 | OEM reference |
| Mercury Marine | 47-161543 | OEM reference format |
| Mercury Marine | 8M0204676 | Reference number |
| Evinrude / Johnson / OMC / BRP | 5040180 | Reference number |
| Sierra | 18-3098 | Aftermarket reference |
| Mallory | 9-45302 | Aftermarket reference |
Engine & Model Compatibility
Fitment is application-specific. Keep the horsepower, stroke, model family, and any carburetor or serial-number conditions together when checking your engine. The table below summarizes the applications explicitly identified for this product and related catalog records.
| Brand | Model or Application | Rated HP | Stroke | Application Notes | Reference |
|---|---|---|---|---|---|
| Nissan | 3.5B / NS5B | 3.5–5 | Not stated in company record | Confirm exact model designation | 369-65021-1 |
| Tohatsu | 2 HP | 2 | 2-Stroke | Company-listed application | 369-65021-1 |
| Tohatsu | 2.5 HP; 2.5A; 3.5A; 3.5B | 2.5–3.5 | 2-Stroke | Company-listed application | 369-65021-1 |
| Tohatsu | 3.5 HP | 3.5 | 2-Stroke | Company-listed application | 369-65021-1 |
| Tohatsu | 4 HP / 5 HP | 4–5 | 2-Stroke | Company-listed application | 369-65021-1 |
| Tohatsu | MFS4 / MFS5 / MFS6 | 4–6 | 4-Stroke | Company-listed application | 369-65021-1 |
| Mercury / Mariner | 4-stroke 2 HP, 2.5 HP, and 3.5 HP carbureted models | 2–3.5 | 4-Stroke | Confirm carburetor version and exact model | 47-16154-3 |
Technical Specs
- Product Type
- Water Pump Impeller
- Product Construction
- Rubber impeller
- Installation
- Replacement water pump component
- Inside Diameter
- 10.25 mm
- Outside Diameter
- 33.6 mm
- Width
- 14.2 mm
- Blade Configuration
- 6 blades
- Quantity
- 1 impeller
What's in the Box
- 1 x aftermarket water pump impeller
Installation Notes
- Confirm the engine model, stroke, application details, and original impeller reference before starting work.
- Follow the outboard manufacturer's service procedure for removing the lower unit and water pump housing.
- Remove the old impeller and inspect the housing, wear plate, key, water tube, and related pump components for damage or corrosion.
- Clean debris and corrosion from the pump area before installing the replacement impeller.
- Install the impeller in the same orientation specified by the service manual. Use only an installation lubricant approved for the application.
- Reassemble the water pump and lower unit using the manufacturer's tightening sequence and torque specifications.
- Run the engine only in an appropriate water supply or service tank and verify a strong cooling-water discharge before normal operation.
Troubleshooting & FAQ
How do I confirm that this impeller fits my engine?
Compare your original impeller's reference number and dimensions, then check the complete engine model, horsepower, stroke, and application details against the compatibility information above. For Mercury/Mariner models, confirm the 4-stroke 2 HP, 2.5 HP, or 3.5 HP carbureted application. If the model or part details differ, consult the engine service manual before ordering.
What are common signs of a worn water pump impeller?
A weak or missing tell-tale stream, overheating, or visible cracked, brittle, distorted, or missing blades can indicate that the impeller or another cooling-system component requires service.
Is this an OEM part?
This is an aftermarket replacement impeller. The OEM and aftermarket numbers shown above are reference numbers used to help identify applications; the product is not represented as a genuine OEM component.
Does the package include a key, gasket, or water pump housing?
No. The package contains one water pump impeller only. A key, gasket, housing, wear plate, or complete water pump kit is not included unless separately stated in the order details.
How often should the impeller be replaced?
Replacement timing depends on the engine manufacturer's maintenance schedule and operating conditions. Inspect the impeller during scheduled water pump service and replace it if the blades show wear, cracking, distortion, or damage.
Safety & Important Information
- Verify the original part number, dimensions, engine model, horsepower, and stroke before purchase.
- Do not rely on horsepower alone to determine fitment; model family and application details can change the required impeller.
- Use the manufacturer's service manual for lower-unit removal, installation orientation, torque specifications, and testing procedures.
- This is an aftermarket replacement component and is not a genuine OEM part.
- Professional installation by a qualified marine technician is recommended when the required service procedure is unfamiliar.
About Sea Sierra
- Marine Replacement Parts — We provide aftermarket components for routine outboard maintenance and repair.
- Application-Focused Information — Product references and fitment details are presented to help customers compare their original part and engine specifications.
- Practical Service Support — Follow the engine manufacturer's service instructions for safe installation and reliable operation.
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