Water Pump Impeller – Fits Tohatsu & Nissan 9.9HP-20HP (Replaces 334-65021-0, 47-803748, 19210-935-003, 5040046)
Water Pump Impeller – Fits Tohatsu & Nissan 9.9HP-20HP (Replaces 334-65021-0, 47-803748, 19210-935-003, 5040046) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
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 Impeller – Fits Tohatsu & Nissan 9.9HP-20HP (Replace...
Product Details
This aftermarket Water Pump Impeller – Fits Tohatsu & Nissan 9.9HP-20HP is designed for reliable performance in 2-stroke and 4-stroke outboard motors. It serves as a crucial component for engine cooling, fitting a wide range of Tohatsu models (M9.9, M12, M15, M18, MFS9.9, MFS15, MFS18, MFS20) and Nissan outboards (NS9.9, NS15, NS18, NSF9.9, NSF15, NSF18, NSF20).
It serves as a direct interchange for several OEM and aftermarket part numbers, including Tohatsu 334-65021-0, Nissan 334-65021-0, Mercury 47-803748, Honda 19210-935-003, Evinrude 5040046, and Sierra 18-8921.
- Installation: Installs as a direct replacement for the original part.
- Environment: Engineered with a plastic hub for saltwater use.
- Inclusions: Includes one high-quality water pump impeller.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Tohatsu | 334-65021-0 / 334650210 / 334650210M |
| Nissan | 334-65021-0 / 334650210 / 334650210M |
| Mercury | 47-803748 / 8M0214944 |
| Honda | 19210-935-003 |
| Evinrude | 5040046 |
| Sierra | 18-8921 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This impeller is known to fit the following Tohatsu 2-stroke and 4-stroke outboard models.
It is also compatible with the listed Nissan 2-stroke and 4-stroke outboard models.
| Brand | Model | Rated HP | Stroke | OEM Part No. |
|---|---|---|---|---|
| Tohatsu | M9.9 | 9.9 | 2-Stroke | 334-65021-0 |
| Tohatsu | M12 | 12 | 2-Stroke | 334-65021-0 |
| Tohatsu | M15 | 15 | 2-Stroke | 334-65021-0 |
| Tohatsu | M18 | 18 | 2-Stroke | 334-65021-0 |
| Tohatsu | MFS9.9 | 9.9 | 4-Stroke | 334-65021-0 |
| Tohatsu | MFS15 | 15 | 4-Stroke | 334-65021-0 |
| Tohatsu | MFS18 | 18 | 4-Stroke | 334-65021-0 |
| Tohatsu | MFS20 | 20 | 4-Stroke | 334-65021-0 |
| Nissan | NS9.9 | 9.9 | 2-Stroke | 334-65021-0 |
| Nissan | NS15 | 15 | 2-Stroke | 334-65021-0 |
| Nissan | NS18 | 18 | 2-Stroke | 334-65021-0 |
| Nissan | NSF9.9 | 9.9 | 4-Stroke | 334-65021-0 |
| Nissan | NSF15 | 15 | 4-Stroke | 334-65021-0 |
| Nissan | NSF18 | 18 | 4-Stroke | 334-65021-0 |
| Nissan | NSF20 | 20 | 4-Stroke | 334-65021-0 |
Technical Specs
- Product Type
- Water Pump Impeller
- Installation
- Direct Replacement
- Fuel Type
- Gasoline
- Housing Material
- Plastic Hub
- Dimensions
- Overall Diameter: 41.11mm, Height: 23.51mm, Internal Shaft Insert Diameter: 13.88mm
- Weight
- 12g (0.42oz)
- Number of Blades
- 8
- Other Technical Attributes
- For saltwater use
What’s in the Box
- 1 x Water Pump Impeller (334-65021-0)
Installation Notes
- Disconnect the battery and remove the engine cover before starting.
- Locate and unbolt the lower unit (gearcase) from the engine's midsection and carefully lower it.
- Remove the water pump housing bolts and lift the housing to expose the old impeller.
- Take note of the blade direction of the old impeller before removing it from the driveshaft.
- Clean the interior of the water pump housing and inspect the wear plate for scoring or damage.
- Slide the new impeller onto the driveshaft. Turn the driveshaft clockwise while pressing down to correctly seat the blades inside the housing cup.
- Reinstall the water pump housing, ensuring any gaskets are properly aligned.
- Reattach the lower unit to the engine, refill the gear oil, and secure all bolts.
- Once assembled, test the engine in water to confirm a steady stream from the cooling system's tell-tale port.
Troubleshooting & FAQ
How do I know if this impeller fits my specific engine?
The best way to confirm fitment is to match your original part number to the references in our Part Number Matrix. You can also check your model against the Engine & Model Compatibility table. If you are still unsure, please check the images and specifications against your old part before ordering.
What are the signs of a failing water pump impeller?
Common signs include a weak or non-existent water stream from the engine's tell-tale port, engine overheating alarms, or a noticeable decrease in engine performance. A visual inspection may show cracked, stiff, or broken blades.
How often should I replace my outboard's impeller?
As a general maintenance rule, it is recommended to replace the water pump impeller every 1-2 years or every 100-200 hours of use, whichever comes first. This interval may be shorter if you frequently operate in sandy, silty, or saltwater conditions.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
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.
