Gearcase Drain Plug Seal – Fits Mercury/Mariner/MerCruiser (Replaces 26-830749, 8M0204693)
Gearcase Drain Plug Seal – Fits Mercury/Mariner/MerCruiser (Replaces 26-830749, 8M0204693) 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
Gearcase Drain Plug Seal – Fits Mercury/Mariner/MerCruiser (Replace...
Product Details
This Gearcase Drain Plug Seal – Fits Mercury/Mariner/MerCruiser Marine Engines (Replaces 26-830749, 8M0204693) is designed for use with a wide range of Mercury/Mariner outboard engines and MerCruiser sterndrive units. It functions as a sealing washer for gearcase drain and fill plugs, effectively preventing gear oil leakage and water intrusion into the lower unit.
It serves as a direct replacement for Mercury part numbers 26-830749 and 8M0204693, Sierra 18-2244, and is an OEM-equivalent part from JLM Marine.
- Simple washer-style gasket for quick replacement during routine gear oil changes.
- Engineered with a durable rubber/composite material to withstand harsh marine environments.
- Ensures a tight seal for lower unit gearcase drain and fill plugs.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 26-830749 |
| Mercury | 8M0204693 |
| Sierra | 18-2244 |
| JLM Marine | OEM equivalent |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury, Mariner, and MerCruiser applications, this seal is used with standard gearcase drain plugs (like 10-79953Q04) on various outboards and sterndrives.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury/Mariner | EFI Outboards | 30, 40, 75, 80, 90, 115, 125 | 4-Stroke | 26-830749/8M0204693 | 3-Cylinder EFI models | |
| Mercury/Mariner | Various Outboards | 30-300 | 2-Stroke & 4-Stroke | 26-830749/8M0204693 | Used with standard gearcase drain plugs | |
| MerCruiser | Alpha & Bravo Sterndrives | N/A | N/A | 2001–2011 | 26-830749/8M0204693 | Used with 10-79953Q04 drain plug |
| Mercury Marine | 350 Mag MPI Hor Alpha & Bravo | N/A | N/A | 2001–2011 | 26-830749/8M0204693 | Per Alibaba listing |
Technical Specs
- Product Type
- Gearcase Drain Plug Seal/Gasket
- Installation
- Simple replacement; used with drain plug screw
- Connection
- Lower Unit Gearcase Drain/Fill Plugs
- Housing Material
- Rubber/Composite
- Housing Color
- Yellow
- Fitting Type
- Washer/Gasket for threaded plug
- Thread Size
- Compatible with 3/8-16 drain plugs
- Warranty
- 1 year (aftermarket)
- Other Technical Attributes
- Designed to withstand marine environments and prevent gear oil leakage; prevents water intrusion into gearcase
What’s in the Box
- 1 x Gearcase Drain Plug Seal (26-830749/8M0204693)
- 10 x Seals when purchased in 10-pack configuration
Installation Notes
- Position a suitable drain pan under the lower unit's gearcase.
- Using a large flathead screwdriver or appropriate socket, carefully remove both the upper (vent) and lower (drain) plug screws.
- Allow the gear oil to drain completely. Inspect the oil for any signs of water intrusion (milky appearance) or metal shavings.
- Remove the old seal from each drain plug. Clean the plug threads and the sealing surface on the gearcase.
- Place the new seal onto the drain plug screw.
- Reinstall the lower drain plug first and tighten it to the manufacturer's specified torque. Do not overtighten.
- Fill the gearcase with the recommended marine gear lubricant through the upper vent hole until fluid begins to flow out.
- Reinstall the upper vent plug with its new seal and tighten securely. Check for any leaks around both plugs.
Troubleshooting & FAQ
How do I know if this seal will fit my engine?
The best way to confirm fitment is to check your OEM part number. This seal replaces Mercury/Mariner/MerCruiser parts 26-830749 and 8M0204693. You can also consult the compatibility table on this page, but always verify against your existing part, as model years can vary.
What are the signs of a failing gearcase seal?
A common sign is gear oil leaking from the drain plug area. You may also notice water intrusion into your gear oil, which will make the oil appear milky or creamy. Any visible cracking or deformation on the old seal during an oil change indicates it's time for a replacement.
How often should this seal be replaced?
It is best practice to replace the gearcase drain plug seals every time you change your gear oil. This is typically recommended once per season or every 100 hours of operation, whichever comes first.
Is this seal resistant to saltwater?
Yes, this seal is made from a durable rubber/composite material designed to withstand exposure to both saltwater and freshwater marine environments, as well as resist degradation from gear lubricants.
Will this seal fit a non-magnetic drain plug?
Yes, this washer is compatible with both standard magnetic and non-magnetic 3/8-16 drain plugs used in the specified Mercury, Mariner, and MerCruiser applications.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials and manufactured in an ISO 9002 facility, with batch inspections for consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options will appear at checkout where available.
Warranty & returns?
This product is covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. See our policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against 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 quality control.
Payment & Security
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