Lower Unit Gasket Kit – Fits Yamaha 8/9.9HP Outboards (Replaces 69G-W0001-20-00)
Lower Unit Gasket Kit – Fits Yamaha 8/9.9HP Outboards (Replaces 69G-W0001-20-00) 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 Lower Unit Gasket Kit – Fits Yamaha 8/9.9HP Outboards (Replaces 69G-W0001-20-00) provides all the necessary seals and gaskets to service the lower unit gear housing on Yamaha 8HP and 9.9HP 4-stroke outboards from 2001 and newer, including T8 and T9.9 high thrust models.
It serves as a direct replacement for Yamaha part number 69G-W0001-20-00 and Sierra part number 18-0025, ensuring a precise fit and reliable seal.
- Engineered for direct replacement of the original components.
- Contains all required seals and gaskets for a complete lower unit service.
- Designed to meet or exceed original equipment specifications for durability.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 69G-W0001-20-00 |
| Yamaha | 69GW000120 |
| Sierra | 18-0025 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit is designed exclusively for the following Yamaha outboard models.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | F8C | 8 | 4-Stroke | 2001 and newer | 69G-W0001-20-00 | |
| Yamaha | F8F | 8 | 4-Stroke | 2001 and newer | 69G-W0001-20-00 | |
| Yamaha | FT8 | 8 | 4-Stroke | 2001 and newer | 69G-W0001-20-00 | High thrust model |
| Yamaha | F9.9F | 9.9 | 4-Stroke | 2001 and newer | 69G-W0001-20-00 | |
| Yamaha | F9.9J | 9.9 | 4-Stroke | 2001 and newer | 69G-W0001-20-00 | |
| Yamaha | FT9.9 | 9.9 | 4-Stroke | 2001 and newer | 69G-W0001-20-00 | High thrust model |
Technical Specs
- Product Type
- Lower Unit Gasket Kit
- Installation
- Direct replacement
- Weight
- 0.04 LBS (0.02 kg)
- Dimensions
- 15.5" L x 15.5" W x 3.0" H
- Other Technical Attributes
- Contains seals and gaskets for the lower unit gear housing
What’s in the Box
- A complete gasket and seal kit for the lower unit gear housing.
Installation Notes
- Disconnect the battery and ensure the engine is in neutral.
- Place a drain pan under the lower unit and remove the drain/fill screws to empty the gear oil.
- Remove the bolts securing the lower unit to the engine housing.
- Carefully separate the lower unit from the driveshaft housing. Be mindful of the shift shaft.
- Disassemble the gear housing components as needed to access all seals and gaskets, noting their original positions.
- Thoroughly clean all mating surfaces, removing any old gasket residue or sealant.
- Install the new gaskets and seals from the kit, applying a light coat of marine grease where appropriate.
- Reassemble the lower unit components, torquing all fasteners to the manufacturer's specifications.
- Reinstall the lower unit, ensuring the driveshaft, water tube, and shift shaft are correctly aligned.
- Refill the gearcase with the recommended marine gear lubricant until it seeps from the upper vent hole.
- Install and tighten the vent and fill screws, then check for any leaks.
Troubleshooting & FAQ
Will this kit fit my specific Yamaha 9.9HP model?
This kit is designed for Yamaha 8HP (F8, FT8) and 9.9HP (F9.9, FT9.9) 4-stroke models manufactured in 2001 and newer. Always verify your engine's model and year against the compatibility chart before ordering.
What are signs my lower unit gaskets are failing?
Common signs include a milky or cloudy appearance in your gear lube (indicating water intrusion), visible oil leaks around the propeller shaft or drain screws, or a recurring loss of gear oil.
How often should lower unit gaskets be replaced?
It's recommended to inspect gaskets and seals during your annual service or whenever the lower unit is removed. They should be replaced if you see any signs of wear, damage, or leakage, or as a preventative measure every few seasons, especially in saltwater environments.
Is this kit different from the OEM Yamaha version?
Our aftermarket kit is manufactured to meet or exceed OEM specifications using comparable, high-quality materials. It is designed to offer the same performance and fit as the original Yamaha part at a better value.
Do I need special tools to install this kit?
Standard marine mechanic tools are typically sufficient, including a socket/wrench set, a screwdriver, a gear lube pump, and a torque wrench. A seal puller can also be helpful for removing old seals without damaging the housing.
Can I buy individual seals or gaskets from this kit?
This product is sold as a complete kit to ensure all necessary components for a lower unit reseal are available. We do not sell the individual gaskets or seals separately.
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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