Yamaha Lower Unit Seal Kit – Fits Yamaha 15-25HP (Replaces 66M-W0001-20)
Yamaha Lower Unit Seal Kit – Fits Yamaha 15-25HP (Replaces 66M-W0001-20) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Product Details
This Yamaha Lower Unit Seal Kit – Fits Yamaha 15-25HP (Replaces 66M-W0001-20) provides all necessary gaskets and seals for servicing the lower unit on Yamaha 15-25 HP 4-stroke outboard motors. It ensures a precise, direct fit to restore gearcase integrity and prevent water intrusion.
This kit is a direct replacement for Yamaha OEM part 66M-W0001-20 and Parsun equivalent REC66M-W0001-20.
- Designed for a direct fit on the lower unit/gear housing.
- Includes a comprehensive set of seals and gaskets for a complete service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 66M-W0001-20 |
| Parsun | REC66M-W0001-20 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit is confirmed to fit the following Yamaha outboard models. Please verify your specific model and year before ordering.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | F15/F20 | 15-25 | 4-Stroke | 66M-W0001-20 | Lower unit gasket kit |
Technical Specs
- Product Type
- Lower Unit Seal Kit
- Installation
- Lower Unit/Gear Housing
- Fitting Type
- Direct Fit
- Package Dimensions
- L: 33.0, W: 19.0, H: 5.0
- Other Technical Attributes
- Includes seals and gaskets for complete lower unit service
What’s in the Box
- 1 x O-Ring (93210-56M80-00)
- 1 x O-Ring (93210-06ME6-00)
- 1 x Impeller (63V-44352-01-00)
- 1 x Gasket (90430-14M09-00)
- 1 x Seal (66M-45128-00-00)
- 1 x GASKET (90430-08020-00)
- 1 x Upper Casing Gasket (66M-45113-00-00)
- 1 x Water Seal Damper (63V-44365-10-00)
- 1 x Cartridge Outer Plate (63V-44323-00-00)
- 1 x Seal Ext (66M-41138-00-00)
- 1 x O-Ring (93210-57M09-00)
- 1 x Oil Seal (93101-20048-00)
- 1 x Lower Casing Packing (63V-45315-A0-00)
- 1 x Oil Seal (93101-12M63-00)
- 1 x GASKET, EXHAUST MANIFOLD 1 (66M-41133-00-00)
- 1 x Upper Casing Gasket (66M-45115-00-00)
- 1 x Oil Seal (93101-17054-00)
- 1 x Water Seal Rubber (63V-44368-00-00)
- 1 x Cartridge Insert (63V-44322-00-00)
- 1 x O-RING (93210-44398-00)
Installation Notes
- Ensure the engine is off and securely positioned. Drain the gearcase oil completely into a suitable container.
- Remove the bolts securing the lower unit to the upper casing. Carefully detach and lower the unit.
- Disassemble the water pump housing and gearcase components, taking note of the order and orientation of each part.
- Carefully extract all old seals, gaskets, and o-rings that are being replaced by this kit.
- Thoroughly clean all mating surfaces, removing any old gasket material, corrosion, or debris.
- Apply a thin coat of marine grease to the new seals and o-rings before installation to ensure a proper seal and prevent damage.
- Install the new seals and gaskets from the kit in their correct locations, ensuring they are seated properly.
- Reassemble the water pump and other components in reverse order of disassembly.
- Reattach the lower unit to the engine, tightening bolts to the manufacturer's specified torque.
- Refill the gearcase with the correct type and amount of fresh marine gear oil. Check for leaks before operation.
Troubleshooting & FAQ
How do I confirm this kit fits my engine?
This kit is designed for Yamaha F15, F20, and other 15-25 HP 4-stroke models. The best way to confirm fitment is to match your engine's original part number to 66M-W0001-20 or the cross-references listed in our Part Number Matrix.
What are signs my lower unit seals are failing?
Common symptoms include a milky, grey, or creamy appearance in your gear lube, indicating water intrusion. You might also notice gear oil leaking from the propeller shaft or weep holes. A burning smell from the lower unit can also be a sign of oil loss and overheating.
How often should lower unit seals be replaced?
As a preventative measure, it's good practice to inspect seals whenever you change your gear lube (at least annually). We recommend replacing the seals every 3-5 years or if you notice any signs of leaks or water intrusion, whichever comes first.
Does this kit include the water pump impeller?
Yes, this comprehensive kit includes the water pump impeller (63V-44352-01-00) along with the necessary plates, seals, and gaskets for a full lower unit and water pump service.
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
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