Water Pump Impeller – Fits Tohatsu/Nissan/Mercury 9.9/15/18/20 HP (Replaces 334-65021-0, 334-65021-1)
Water Pump Impeller – Fits Tohatsu/Nissan/Mercury 9.9/15/18/20 HP (Replaces 334-65021-0, 334-65021-1) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Water Pump Impeller – Fits Tohatsu/Nissan/Mercury 9.9/15/18/20 HP (...
Product Details
This Water Pump Impeller – Fits Tohatsu/Nissan/Mercury 9.9/15/18/20 HP is a direct replacement component for the cooling systems of various outboard engines. It is designed to fit a wide range of Tohatsu/Nissan 9.9–20 HP (2-Stroke & 4-Stroke), Mercury/Mariner 9.9–20 HP, and Honda 7.5–10 HP 4-Stroke models.
This impeller serves as an interchange for numerous OEM and aftermarket part numbers, including Tohatsu/Nissan 334-65021-0, Mercury 47-803748, Honda 19210-935-003, and Sierra 18-8921.
- Installation Method: Direct OEM replacement
- Engine Position: Outboard
- Application: Marine outboard cooling system
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Tohatsu / Nissan | 334-65021-0 |
| Tohatsu / Nissan | 334-65021-1 |
| Tohatsu / Nissan | 334-65021-00 |
| Tohatsu / Nissan | 334-65021-0M |
| Mercury | 47-803748 |
| Mercury | 47-8M0214944 |
| Mercury | 8M0135803 |
| Honda | 19210-935-003 |
| Honda | 19210-935-A01 |
| Sierra | 18-8921 |
| CEF | 500383 |
| Johnson / Evinrude | 5040046 |
| Johnson / Evinrude | 05040046 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Tohatsu/Nissan: Compatible with a variety of 2-stroke and 4-stroke models from 9.9 HP to 25 HP.
Mercury/Mariner: Fits 9.9 HP, 15 HP, and 20 HP models (both 2-stroke and 4-stroke).
Honda: Designed for BF7.5 (7.5 HP) and BF10 (10 HP) 4-stroke outboard engines.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Tohatsu | F9.9B2 | 9.9 | 4-Stroke | 334-65021-0 | ||
| Tohatsu | F15B2 | 15 | 4-Stroke | 334-65021-0 | ||
| Tohatsu | F18B2 | 18 | 4-Stroke | 334-65021-0 | ||
| Tohatsu | F9.9C | 9.9 | 4-Stroke | 334-65021-0 | ||
| Tohatsu | F15C | 15 | 4-Stroke | 334-65021-0 | ||
| Tohatsu | F20C | 20 | 4-Stroke | 334-65021-0 | ||
| Tohatsu | MFS9.9C | 9.9 | 4-Stroke | 334-65021-0 | ||
| Tohatsu | MFS15C | 15 | 4-Stroke | 334-65021-0 | ||
| Tohatsu | MFS20C | 20 | 4-Stroke | 334-65021-0 | ||
| Tohatsu | 9.9D | 9.9 | 2-Stroke | 334-65021-0 | ||
| Tohatsu | 15D2 | 15 | 2-Stroke | 334-65021-0 | ||
| Tohatsu | 18E2 | 18 | 2-Stroke | 334-65021-0 | ||
| Tohatsu | M9.9D2 | 9.9 | 2-Stroke | 334-65021-0 | ||
| Tohatsu | M15D2 | 15 | 2-Stroke | 334-65021-0 | ||
| Tohatsu | M18E2 | 18 | 2-Stroke | 334-65021-0 | ||
| Tohatsu | M16A2 | 16 | 2-Stroke | 334-65021-0 | ||
| Tohatsu | M20A2 | 20 | 2-Stroke | 334-65021-0 | ||
| Tohatsu | M25A2 | 25 | 2-Stroke | 334-65021-0 | ||
| Mercury | 9.9 | 9.9 | 2-Stroke & 4-Stroke | 47-803748 | ||
| Mercury | 15 | 15 | 2-Stroke & 4-Stroke | 47-803748 | ||
| Mercury | 20 | 20 | 2-Stroke & 4-Stroke | 47-803748 | ||
| Honda | BF7.5 | 7.5 | 4-Stroke | 19210-935-003 | ||
| Honda | BF10 | 10 | 4-Stroke | 19210-935-003 |
Technical Specs
- Product Type
- Water Pump Impeller
- Installation
- Direct OEM replacement
- Material
- Rubber (Neoprene)
- Number of Blades
- 8
- Shaft Size
- 13.8 mm
- Outer Diameter
- 41 mm
- Impeller Width
- 23.5 mm
- Weight
- 50 g (1.76 oz)
- Product Dimensions
- 18.0 cm x 10.5 cm x 2.5 cm
What’s in the Box
- 1 × Water Pump Impeller
Installation Notes
- Disconnect the battery and remove the engine cover.
- Locate and remove the lower unit (gearcase) by unfastening the mounting bolts.
- Place the lower unit on a workbench and remove the water pump housing cover screws.
- Carefully lift the housing, noting the orientation of the old impeller.
- Remove the old impeller, drive key, and gaskets. Clean all mating surfaces thoroughly.
- Install new gaskets and insert the drive key onto the driveshaft.
- Slide the new impeller onto the driveshaft, rotating the shaft clockwise while pushing down to bend the blades correctly.
- Apply a light coat of marine-grade grease or a soap-and-water solution inside the pump housing.
- Reinstall the water pump housing, ensuring a proper seal, and tighten screws to the manufacturer's torque specifications.
- Reattach the lower unit to the engine and reconnect the battery.
- Start the engine with a proper water supply (e.g., using flushing muffs) to verify water is pumping from the tell-tale outlet.
Troubleshooting & FAQ
How do I know if this impeller fits my engine?
First, check if your original part number is listed in our Part Number Matrix. Second, find your engine in the Engine & Model Compatibility table. If your part number or engine model is listed, it is compatible. For complete peace of mind, compare the dimensions in the Technical Specs with your old part before ordering.
The impeller blades look bent. Is it defective?
No, this is normal. Impeller blades are flexible and must be bent during installation to fit inside the pump housing. To install, rotate the driveshaft in its normal direction of operation (usually clockwise) while pressing the impeller down to ensure blades bend correctly without damage.
How often should I replace my water pump impeller?
As a general maintenance rule, you should inspect your impeller annually and replace it every 1-2 years or every 100-200 hours of operation, whichever comes first. This interval can change based on usage conditions (e.g., frequent use in sandy/silty water may require more frequent changes).
What are the signs of a failing impeller?
Common symptoms of a worn or damaged impeller include a weak or non-existent water stream from the "tell-tale" outlet, engine overheating alarms, steam from the exhaust, or finding brittle, cracked, or stiff blades during a visual inspection.
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.
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