Water Pump Impeller Kit – Fits Mercury/Mariner, Tohatsu 2.5 & 3.5 HP (Replaces 8M0181314, 47-161543, 369-65021-1, 309-65021-1)
Water Pump Impeller Kit – Fits Mercury/Mariner, Tohatsu 2.5 & 3.5 HP (Replaces 8M0181314, 47-161543, 369-65021-1, 309-65021-1) 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.
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Water Pump Impeller Kit – Fits Mercury/Mariner, Tohatsu 2.5 & 3...
Water Pump Impeller Kit – Fits Mercury/Mariner, Tohatsu 2.5 & 3.5 HP (Replaces 8M0181314, 47-161543, 369-65021-1, 309-65021-1) is backordered and will ship as soon as it is back in stock.
Product Details
This Water Pump Impeller Kit is a direct-fit replacement designed for Mercury/Mariner and Tohatsu 2.5 HP and 3.5 HP 4-stroke outboard engines manufactured from 2006 onwards. For Mercury models, it is essential to confirm that your engine's serial number is 0R131842 or higher to ensure compatibility, as these are Tohatsu-manufactured powerheads.
It directly interchanges with Mercury part numbers 8M0181314 and 47-161543, as well as Tohatsu equivalents 369-65021-1 and 309-65021-1, providing a reliable and cost-effective solution for routine lower unit maintenance.
- Installs directly with standard marine service tools.
- The neoprene impeller is engineered for durability in both freshwater and saltwater environments.
- Manufactured in an ISO 9002 certified facility for consistent quality and performance.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Mercury | 8M0181314 |
| Mercury | 47-161543 |
| Tohatsu | 369-65021-1 |
| Tohatsu | 309-65021-1 |
Engine & Model Compatibility
Confirm your engine model and year in the table below to ensure accurate fitment.
For Mercury/Mariner owners: Your engine must have a serial number of 0R131842 or higher. These models are mechanically identical to their Tohatsu counterparts.
For Tohatsu owners: This kit fits MFS2.5 and MFS3.5 models from 2006 and newer. Check your OEM part number to verify.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | F2.5 | 2.5 | 4-Stroke | 2006 and newer | 8M0181314 / 47-161543 | SN 0R131842+ (Tohatsu-manufactured) |
| Mercury | F3.5 | 3.5 | 4-Stroke | 2006 and newer | 8M0181314 / 47-161543 | SN 0R131842+ (Tohatsu-manufactured) |
| Tohatsu | MFS2.5 | 2.5 | 4-Stroke | 2006 and newer | 369-65021-1 / 309-65021-1 | Parts identical to Mercury |
| Tohatsu | MFS3.5 | 3.5 | 4-Stroke | 2006 and newer | 369-65021-1 / 309-65021-1 | Parts identical to Mercury |
Technical Specs
- Product Type
- Water Pump Impeller Kit
- Installation
- Direct replacement with standard tools
- Material
- Neoprene rubber impeller with plastic hub
- Number of Blades
- 6
- Hub Diameter
- 0.472 in (12 mm)
- External Diameter
- 1.693 in (43 mm)
- Thickness
- 0.563 in (14.3 mm)
- Fitment Type
- Direct OEM replacement
- Warranty
- 1 Year (aftermarket)
- Production Standards
- ISO9002 certified manufacturing
What’s in the Box
- 1 x Water Pump Impeller (369-65021-1 / 309-65021-1)
- 1 x Water Pump Gasket (3F0-65018-0)
- 1 x Water Pump Gasket (3F0-65029-0)
- 1 x Impeller Key (369-65022-0)
- 2 x Gearbox Drain/Fill Screw Fibre Washer (332-60006-0)
Installation Notes
- Disconnect the spark plug lead to prevent accidental starting.
- Place a drain pan under the gearcase and remove the drain/fill screws to empty the gear oil.
- Remove the bolts securing the lower unit (gearcase) to the midsection and carefully lower it.
- Unbolt and remove the water pump housing to access the old impeller.
- Clean any debris or old gasket material from the housing and base plate.
- Install the new impeller key, gaskets, and impeller. Ensure the impeller vanes are oriented correctly (typically clockwise).
- Reassemble the housing, reinstall the lower unit, and refill the gearcase with fresh oil using new washers.
- Reconnect the spark plug lead, start the engine in water, and confirm a steady stream from the "tell-tale" outlet.
Important: This kit is not compatible with any 2-stroke engines, which use a different water pump design.
Troubleshooting & FAQ
How do I know if this impeller fits my specific engine?
This kit fits Mercury/Mariner 2.5/3.5 HP 4-stroke models with serial number 0R131842 or higher, and Tohatsu MFS2.5/MFS3.5 4-stroke models from 2006+. It is critical to verify your engine's model, horsepower, and serial number (for Mercury) before ordering. It does not fit any 2-stroke engines.
When should I replace my water pump impeller?
For preventative maintenance, it is recommended to replace the impeller every 1-2 years or every 100-200 hours of operation. Service intervals should be shorter if operating frequently in sandy, silty, or saltwater conditions.
What are the signs of a failing impeller?
The most common signs include a weak or no water stream from the engine's tell-tale (pee hole), or an engine overheating alarm. Reduced engine performance can also be an indicator. Immediate inspection is required if you notice these symptoms.
What makes this kit different from an OEM Quicksilver kit?
Our kit contains all the essential core components for a standard water pump service: the impeller, key, and necessary gaskets. Some OEM service kits (like Quicksilver's 8M0181314) may include additional small hardware like shear pins or cotter pins. Our components are manufactured to the same specifications for fit and function.
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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