Water Pump Impeller for Tohatsu, Nissan & Mercury Mariner 25–35 HP Outboards – 345-65021-0
Water Pump Impeller for Tohatsu, Nissan & Mercury Mariner 25–35 HP Outboards – 345-65021-0 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Water Pump Impeller for Tohatsu, Nissan & Mercury Mariner 25–35...
Water Pump Impeller for Tohatsu, Nissan & Mercury Mariner 25–35 HP Outboards – 345-65021-0 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket water pump impeller is designed for selected Tohatsu and Nissan 2-stroke and 4-stroke outboard applications, including 25–30 HP 2-stroke models, selected 35 HP 2-stroke models, and 25–30 HP 4-stroke models. The same product is also listed for selected Mercury Mariner 25 and 30 HP EFI 4-stroke applications.
The impeller is a critical cooling-system component that circulates water through the outboard to help maintain proper operating temperature. Always confirm the exact engine model, stroke, year or serial range, and existing impeller part number before ordering.
Part Number Matrix
The following manufacturer and aftermarket references are listed for this impeller. A reference number alone does not replace model-specific fitment verification.
| Brand or source | Reference number | Reference type |
|---|---|---|
| Tohatsu | 345-65021-0; 345650210M; 3R0650210M; 3R0-65021-0 | OEM references |
| Nissan / Tohatsu | 18-8923 | Aftermarket reference: Sierra Marine |
| Nissan / Tohatsu | 9-45400 | Aftermarket reference: Mallory Marine |
| Mercury Mariner | 47-16154 1 | Company-listed OEM reference; verify formatting against the engine documentation |
| Mercury Marine | 161541 | Company-listed reference |
Engine & Model Compatibility
Fitment conditions must remain together. The applications below are grouped by brand, horsepower, and stroke rather than treated as a universal fit across all engines in the same horsepower range.
| Brand | Engine or model family | Rated HP | Stroke | Applicable reference | Fitment note |
|---|---|---|---|---|---|
| Tohatsu | M25C2, M25C3, M25/30H, MX25/30H and related selected models | 25–30 | 2-Stroke | 345-65021-0 | Catalog occurrences support selected M25/M30 and MX25/MX30 applications; verify model and year. |
| Nissan | NS25C2, NS25C3, NS30A3, NS30A4 and related selected models | 25–30 | 2-Stroke | 345-65021-0 | Verify the exact model and engine documentation before purchase. |
| Tohatsu / Nissan | Selected 35 HP models, including M35C or NS35C applications where specified | 35 | 2-Stroke | 345-65021-0 | Company fitment lists selected 35 HP 2-stroke applications; do not extend this listing to 35 HP 4-stroke engines. |
| Tohatsu | MFS25/30B and MFS25/30C families | 25–30 | 4-Stroke | 345-65021-0 | Selected 4-stroke MFS applications are listed; confirm the model generation and serial range. |
| Tohatsu / Nissan | MFS25/30 and related 4-stroke applications | 25–30 | 4-Stroke | 345-65021-0 | Company data explicitly includes 4-stroke MFS25/30 HP fitment. |
| Mercury Mariner | 25 & 30 HP EFI | 25–30 | 4-Stroke | 47-16154 1 | Company data lists this product for selected 4-stroke EFI applications; verify the engine part number before ordering. |
Technical Specifications
- Product Type
- Water pump impeller
- Product Configuration
- Single impeller, not a kit
- Application
- Selected Tohatsu, Nissan, and Mercury Mariner outboards
- Stroke Coverage
- Selected 25–35 HP 2-stroke applications and selected 25–30 HP 4-stroke applications
- Material
- Neoprene rubber
- Number of Blades
- 6
- Inner Diameter
- 17 mm
- Outer Diameter
- 44 mm
- Blade Width
- 20 mm
- Color
- Black
What’s in the Box
- 1 x Water pump impeller
This is a single replacement impeller. The water-pump key, housing, gasket, wear plate, and other service parts are not included unless separately stated. Reuse only serviceable original components or purchase replacement service parts separately as required by the engine manufacturer.
Installation Notes
- Disconnect the battery, place the engine in a stable position, and allow it to cool completely before beginning work.
- Follow the engine service manual for lower-unit removal and gearcase-oil draining requirements.
- Remove the water-pump housing and carefully remove the old impeller.
- Inspect the water-pump key, housing, wear plate, gaskets, and related components. The key is not included with this single-impeller listing.
- Clean the housing and confirm that the new impeller matches the old part in diameter, width, hub, and blade configuration.
- Install the original serviceable key or a separately purchased replacement key, then fit the new impeller according to the service manual.
- Install the housing and new gaskets or seals where required. Tighten fasteners to the manufacturer’s specifications.
- Reassemble the lower unit, refill gearcase oil if applicable, and reconnect all components.
- Run the engine only with an appropriate water supply and confirm a strong cooling-water discharge before returning the boat to service.
Troubleshooting & FAQ
How do I confirm this impeller fits my specific engine?
Match the complete engine model, horsepower, stroke, year or serial range, and existing impeller number. The most useful references for this listing include 345-65021-0, 345650210M, 3R0650210M, 3R0-65021-0, and the listed aftermarket references. Also compare the old impeller’s physical dimensions and hub configuration before ordering.
Does this fit both 2-stroke and 4-stroke engines?
Yes, but not under one unrestricted fitment range. Company data lists selected 25–30 HP 2-stroke applications, selected 35 HP 2-stroke applications, selected Tohatsu/Nissan MFS25/30 HP 4-stroke applications, and selected Mercury Mariner 25/30 HP EFI 4-stroke applications. Verify the exact model and part number.
Does the package include the impeller key?
No. This product is a single impeller rather than a kit. The key and other water-pump service parts are not included.
What are the signs of a failing water-pump impeller?
Common signs include overheating at idle or low speed, a weak or missing telltale-water stream, and a high-temperature warning. A cracked, brittle, or worn impeller may not circulate cooling water effectively.
How often should the impeller be replaced?
Inspect the impeller during scheduled service and replace it according to the engine manufacturer’s maintenance guidance. More frequent inspection may be appropriate for engines used in saltwater, sandy water, silty water, or after extended storage.
Is this an OEM part?
No. This listing is for an aftermarket replacement impeller. The manufacturer and aftermarket numbers shown above are reference numbers used to help identify compatible applications; they do not indicate that this product is manufactured by the original engine brand.
What if my engine is not listed?
Do not assume compatibility solely from horsepower or brand. Compare the exact model, stroke, year or serial range, part number, and impeller dimensions with the information in your service manual or the original part.
Safety & Important Information
- Verify the complete engine model, stroke, horsepower, year or serial range, and part number before purchase.
- Do not operate an outboard without an adequate cooling-water supply.
- Inspect the water-pump housing, key, wear plate, gaskets, and seals during installation.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended if you are not familiar with lower-unit or water-pump service.
About Sea Sierra
- Marine replacement parts selected for common outboard service applications.
- Product information organized around part-number and engine-fitment verification.
- Support for customers who need help comparing an original part with a replacement.
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