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Boat Marine 369-87322-0 Water Pump Impeller Repair Kit for Tohatsu Nissan 4 5 6 HP Outboard Motor NS4C M4C NSF4 MFS4 NS5B M5B NSF5 MFS5 NSF6 MFS6 Replace 369873220M 369873221M

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Boat Marine 369-87322-0 Water Pump Impeller Repair Kit for Tohatsu Nissan 4 5 6 HP Outboard Motor NS4C M4C NSF4 MFS4 NS5B M5B NSF5 MFS5 NSF6 MFS6 Replace 369873220M 369873221M is backordered and will ship as soon as it is back in stock.


Worry-free returns

You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This aftermarket Water Pump Impeller Repair Kit is designed for Tohatsu and Nissan 4 HP, 5 HP, and 6 HP 4-stroke outboard motors, including MFS4, MFS5, MFS6, NSF4, NSF5, and NSF6 series engines. It provides all necessary components for a complete water pump service to restore engine cooling performance.

It serves as a direct replacement for Tohatsu part numbers 369-87322-0, 369873220M, and 369873222M; Nissan 369-87322-1 and 369873221M; and Mercury 16159A03.

  • Engineered for direct-fit installation.
  • Includes impeller, gaskets, and guide plates.
  • Constructed with durable plastic and metal housing components.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand Part Number Superseded By
Tohatsu 369-87322-0
Tohatsu 369873220M 369873222M
Nissan 369-87322-1
Mercury 16159A03

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Tohatsu outboards, this kit fits various M-series and MFS-series 4-stroke engines from 4 HP to 6 HP.

For Nissan outboards, this kit fits NS-series and NSF-series 4-stroke engines from 4 HP to 6 HP.

Brand Model Rated HP Stroke Years OEM Part No. Notes
Tohatsu MFS4B 4 4-Stroke 2002–2014 369-87322-0
Tohatsu MFS4C 4 4-Stroke 2011–2014 369-87322-0
Tohatsu M5B 5 4-Stroke 2003 369-87322-0
Tohatsu MFS5B 5 4-Stroke 2002–2010 369-87322-0
Tohatsu MFS5C 5 4-Stroke 2011–2014 369-87322-0
Tohatsu MFS6B 6 4-Stroke 2002–2010 369-87322-0
Tohatsu MFS6C 6 4-Stroke 2011–2014 369-87322-0
Nissan NSF4B 4 4-Stroke 2002–2010 369-87322-1
Nissan NSF4C 4 4-Stroke 2011–2014 369-87322-1
Nissan NS5B 5 4-Stroke 2003 369-87322-1
Nissan NSF5A2 5 4-Stroke 2002 369-87322-1
Nissan NSF5B 5 4-Stroke 2002–2010 369-87322-1
Nissan NSF5C 5 4-Stroke 2011–2014 369-87322-1
Nissan NSF6B 6 4-Stroke 2002–2010 369-87322-1
Nissan NSF6C 6 4-Stroke 2011–2014 369-87322-1

Technical Specs

Product Type
Water Pump Impeller Repair Kit
Installation
Direct replacement
Housing Material
Plastic + metal
Components
Impeller, gaskets, guide plates
Weight
7.1 ounces (201g)

What’s in the Box

  • 1 x Water Pump Impeller Repair Kit (Replaces 369-87322-0/1/2)

Installation Notes

  1. Disconnect the battery and ensure the outboard is in neutral.
  2. Remove the mounting bolts securing the lower unit (gearcase) and carefully lower it from the engine.
  3. Unbolt and lift the water pump housing to expose the impeller.
  4. Inspect the housing and wear plate; clean or replace them if significant scoring or warping is present.
  5. Remove the old impeller, woodruff key, and gaskets. Clean all mating surfaces thoroughly.
  6. Install the new gaskets, wear plate, and woodruff key onto the driveshaft.
  7. Slide the new impeller onto the driveshaft, turning the shaft clockwise to help seat the vanes correctly inside the housing.
  8. Reinstall the pump housing cover and tighten its bolts to the manufacturer's recommended torque specification.
  9. Carefully guide the lower unit back into place, ensuring the driveshaft, shift shaft, and water tube align correctly. Fasten the mounting bolts.
  10. Test run the engine in water, confirming a steady stream from the cooling system's tell-tale port.

Troubleshooting & FAQ

How do I know if this kit fits my specific model?

First, check the "Engine & Model Compatibility" table to confirm your engine model and year range. Second, use the "Part Number Matrix" to cross-reference your existing part number and ensure it is listed as an equivalent.

What are the signs of a failing water pump impeller?

Common symptoms include a weak or intermittent water stream from the tell-tale (pee-hole), engine overheating alarms, steam from the exhaust, and a reduction in overall engine performance.

How often should I replace my impeller?

For preventative maintenance, it is recommended to inspect and replace the impeller every 1-2 years or every 100-200 hours of use. Service intervals may be shorter in saltwater or silty/sandy 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.

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