Lower Unit Gasket Kit – Fits Yamaha 6HP-8HP Outboards (Replaces 6G1-W0001-C1-00)
Lower Unit Gasket Kit – Fits Yamaha 6HP-8HP Outboards (Replaces 6G1-W0001-C1-00) 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
Lower Unit Gasket Kit – Fits Yamaha 6HP-8HP Outboards (Replaces 6G1...
Product Details
This Lower Unit Gasket Kit is an essential service part for Yamaha 6HP-8HP 2-stroke outboards, covering models from 1997 through 2005 and newer. It contains the necessary components to reseal the gearcase and prevent water intrusion or oil leaks.
The kit serves as a direct interchange for Yamaha part numbers 6G1-W0001-C1-00, 6G1-W0001-C0-00, 6G1-W0001-21-00, and 6N0-W0001-20-00. It also cross-references to Mariner part 11655M.
- Installation: Designed as a direct replacement for OEM parts.
- Included Components: Contains all required gaskets, oil seals, and O-rings for a complete lower unit service.
- Application: Suitable for gasoline-powered 2-stroke outboard marine engines.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By | Notes |
|---|---|---|---|
| Yamaha | 6G1-W0001-21-00 | 6G1-W0001-C0-00 | Original part number. |
| Yamaha | 6G1-W0001-C0-00 | 6G1-W0001-C1-00 | Superseded part. |
| Yamaha | 6G1-W0001-C1-00 | Current OEM part number. | |
| Yamaha | 6N0-W0001-20-00 | Interchangeable part number. | |
| Mariner | 11655M | Direct cross-reference for Mariner applications. |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Yamaha engines, this kit is compatible with various 6 HP and 8 HP 2-stroke models manufactured between 1997 and 2009. Please verify your specific model and year.
For Mariner outboards, this part fits various 6-8 HP 2-stroke models from 1987 onwards. Cross-reference part number 11655M to confirm fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | 6MLHV | 6 | 2-Stroke | 1997 | 6G1-W0001-C1-00 | |
| Yamaha | 6MLHW | 6 | 2-Stroke | 1998 | 6G1-W0001-C1-00 | |
| Yamaha | 6MLHX | 6 | 2-Stroke | 1999 | 6G1-W0001-C1-00 | |
| Yamaha | 6MLHY | 6 | 2-Stroke | 2000 | 6G1-W0001-C1-00 | |
| Yamaha | 6MSHV | 6 | 2-Stroke | 1997 | 6G1-W0001-C1-00 | |
| Yamaha | 6MSHW | 6 | 2-Stroke | 1998 | 6G1-W0001-C1-00 | |
| Yamaha | 6MSHX | 6 | 2-Stroke | 1999 | 6G1-W0001-C1-00 | |
| Yamaha | 6MSHY | 6 | 2-Stroke | 2000 | 6G1-W0001-C1-00 | |
| Yamaha | 8MLHV | 8 | 2-Stroke | 1997 | 6G1-W0001-C1-00 | |
| Yamaha | 8MLHW | 8 | 2-Stroke | 1998 | 6G1-W0001-C1-00 | |
| Yamaha | 8MLHX | 8 | 2-Stroke | 1999 | 6G1-W0001-C1-00 | |
| Yamaha | 8MLHY | 8 | 2-Stroke | 2000 | 6G1-W0001-C1-00 | |
| Yamaha | 8MSHV | 8 | 2-Stroke | 1997 | 6G1-W0001-C1-00 | |
| Yamaha | 8MSHW | 8 | 2-Stroke | 1998 | 6G1-W0001-C1-00 | |
| Yamaha | 8MSHX | 8 | 2-Stroke | 1999 | 6G1-W0001-C1-00 | |
| Yamaha | 8MSHY | 8 | 2-Stroke | 2000 | 6G1-W0001-C1-00 | |
| Yamaha | 8MSHZ | 8 | 2-Stroke | 2001 | 6G1-W0001-C1-00 | |
| Yamaha | 8MSHA | 8 | 2-Stroke | 2002 | 6G1-W0001-C1-00 | |
| Yamaha | 8MSHB | 8 | 2-Stroke | 2003 | 6G1-W0001-C1-00 | |
| Yamaha | 8MSHC | 8 | 2-Stroke | 2004 | 6G1-W0001-C1-00 | |
| Yamaha | 8MSH | 8 | 2-Stroke | 2005–2009 | 6G1-W0001-C1-00 | |
| Yamaha | 8MSHD | 8 | 2-Stroke | 2005 | 6G1-W0001-C1-00 | |
| Mariner | Various | 6-8 | 2-Stroke | 1987+ | 11655M | Compatible with various Mariner 6-8 HP models |
Technical Specs
- Product Type
- Lower Unit Gasket Kit
- Installation
- Direct replacement
- Fuel Type
- Gasoline
- Housing Material
- Various (gaskets, seals, O-rings)
- Package Dimensions
- 17.0" L x 15.0" W x 2.5" H
What’s in the Box
- 1x GASKET (90430-08003-00/90430-08020-00)
- 1x OIL SEAL (93101-11M23-00)
- 1x OIL SEAL (93101-15074-00)
- 1x O-RING (93210-49046-00)
- 1x O-RING (93210-53679-00)
- 1x GASKET, WATER PUMP (6G1-44315-A0-00)
- 1x PACKING, LOWER CASING (6G1-45315-A0-00)
Installation Notes
- Before starting, shift the outboard into neutral, disconnect the battery, and place a drain pan under the gearcase. Remove the drain and vent plugs to empty the gear oil.
- Unbolt the lower unit from the engine's midsection. Be prepared for its weight and carefully lower it, making sure to disconnect any speedometer tube or shift shaft connectors.
- With the lower unit on a workbench, remove the water pump housing and impeller to access the upper seals.
- Continue disassembly as required to reach the propshaft and driveshaft seals. Keep components organized.
- Thoroughly clean all mating surfaces, removing every trace of old gasket material, sealant, or corrosion.
- Carefully install the new seals and O-rings from the kit. Apply a light coat of marine grease to the inner lips of oil seals and on O-rings to prevent damage during assembly.
- Reassemble all components in reverse order of disassembly. Ensure all parts are correctly seated.
- Torque all bolts to the manufacturer's recommended specifications. Uneven or incorrect torque can lead to leaks.
- Re-attach the lower unit to the midsection, reconnecting shift shafts and any other linkages.
- Refill the gearcase with new, high-quality marine gear lubricant until it flows from the upper vent hole. Reinstall and tighten plugs.
- After installation, check for leaks and test engine operation in the water, verifying correct shifting and that the water pump is discharging a steady stream.
Troubleshooting & FAQ
How do I confirm this gasket kit fits my specific engine?
The best way is to first check the compatibility table on this page. Locate your engine's brand, model, horsepower, and year. Second, cross-reference the OEM part number from your old unit against the numbers listed in our Part Number Matrix.
What are common signs that my lower unit gaskets are failing?
The most common sign is "milky" or cloudy gearcase oil, which indicates water has mixed with the lubricant. Other signs include visible oil leaks from the seams of the lower unit, around the prop shaft, or from the drain/vent screws.
How often should I replace my lower unit seals?
As a preventative measure, it is wise to replace lower unit seals and gaskets every 2-3 years, especially in saltwater environments. They should be replaced immediately if you detect any water intrusion or oil leaks.
Are any special tools needed for this job?
You will need a standard set of mechanic's tools, including sockets and wrenches. A torque wrench is highly recommended to ensure bolts are tightened to spec, and a seal puller can make removing old seals much easier.
Will this kit fit my Mariner outboard if the model isn't listed?
This kit is a known service replacement for Mariner part 11655M on many 6-8 HP 2-stroke models. However, because part usage can vary, you must confirm that 11655M is the correct part number for your specific engine before ordering.
What is the difference between an OEM part and this aftermarket kit?
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.
How fast do you ship and what does it cost?
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
What is your warranty and return policy?
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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