Gearcase Drain Plug Seal Gasket – Fits Mercury, Yamaha, Suzuki (Replaces 26-830749, 90430-08003-00)

$7.69 $12.00

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Gearcase Drain Plug Seal Gasket – Fits Mercury, Yamaha, Suzuki (Replaces 26-830749, 90430-08003-00) is backordered and will ship as soon as it is back in stock.

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Product Details

This Gearcase Drain Plug Seal Gasket – Fits Mercury, Yamaha, Suzuki Outboards provides a secure, leak-free seal for the lower unit gear oil drain and fill plugs. It is designed for a wide range of outboard and sterndrive models from Mercury Marine, Mercruiser, Yamaha, and Suzuki that utilize a 3/8"-16 threaded plug.

It serves as a direct replacement for Mercury part 26-830749, Yamaha parts 90430-08003-00, 90430-08020-00, 90430-08801-00, and 604-45342-00-00, and Suzuki part 09168-10022.

Installation: Manual placement over drain/fill plug threads.
Operating Environment: Suitable for both freshwater and saltwater marine use.
Recommended Replacement: Replace with every gear oil change to ensure a proper seal.

Part Number Matrix

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

Brand	Part Number	Notes
Mercury	26-830749
Yamaha	90430-08003-00	Supersedes 90430-08020-00, 90430-08801-00, 604-45342-00-00
Suzuki	09168-10022

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury/Mercruiser, this gasket is used on various sterndrives and outboards equipped with 3/8"-16 drain/fill plugs.

For Yamaha, this part fits all 2-stroke and 4-stroke outboards from 1984 to present.

For Suzuki, this gasket is used on various marine outboards as a gear case lube oil drain plug gasket.

Brand	Models	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury	Various outboards with 3/8-16 drain/fill plugs	Various	2- & 4-Stroke		26-830749	Used for lower unit grease gaskets
Mercruiser	Various sterndrives with 3/8-16 drain/fill plugs	Various			26-830749	Used for lower unit grease gaskets
Yamaha	All outboards	All	2- & 4-Stroke	1984 and newer	90430-08003-00
Suzuki	Marine outboards				09168-10022	Gear case lube oil drain plug bolt gasket

Technical Specs

Product Type: Gearcase Drain Plug Seal Gasket
Installation: Manual placement over drain/fill plug threads
Material: Stainless steel with rubber coating
Color: Varies by brand (Mercury: yellow, Yamaha: black/orange-red)
Application: Lower unit gear oil drain/fill plugs
Thread Size: Compatible with 3/8"-16 thread plugs
Operating Environment: Marine (freshwater and saltwater)
Package Quantity: Available in 6-packs and 10-packs
Recommended Replacement: Every oil change
Warranty: 90 days (varies by seller)

What’s in the Box

Package contents depend on the option selected. Each gasket is an equivalent to Mercury 26-830749 or Yamaha 90430-08003-00.

10-Pack Option: 10 x Gearcase Drain Plug Seal Gaskets
6-Pack Option: 6 x Gearcase Drain Plug Seal Gaskets

Installation Notes

Place a suitable drain pan under the lower unit.
Remove the lower gearcase drain/fill plug screw.
Allow all the old gear oil to drain completely.
Clean the magnetic tip of the drain plug to remove any metal shavings.
Remove and discard the old gasket from the drain plug.
Install the new gasket onto the clean drain plug.
Reinstall the drain plug and tighten it to the manufacturer's specified torque. Do not overtighten.
Remove the upper (vent) plug and fill the gearcase with the recommended lube until it flows from the vent hole.
Reinstall the vent plug with a new gasket, then quickly reinstall the bottom fill plug.
Check for any leaks around both plugs.

Troubleshooting & FAQ

How do I know if this gasket fits my engine?

This gasket is compatible with any Mercury, Mercruiser, Yamaha, or Suzuki lower unit that uses a 3/8"-16 drain/fill plug. Cross-reference your old gasket's part number with the numbers listed in our Part Number Matrix to confirm fitment.

What are the signs of a failing gearcase gasket?

The most common sign is a gear lube leak from the drain or fill plug. You may also see a milky or creamy appearance in the gear oil, which indicates water intrusion. Always replace gaskets during a gear lube change to prevent this.

Can I reuse my old drain plug gasket?

It is strongly recommended to use a new gasket with every oil change. Reusing an old, compressed gasket significantly increases the risk of a leak, which can lead to catastrophic lower unit failure from water intrusion.

What's the difference between the gasket colors?

The color (e.g., yellow, black, orange-red) is typically a brand-specific choice and does not affect the gasket's function or fit. These aftermarket gaskets are designed to meet the specifications for all listed part numbers, regardless of the original color.

Does this gasket work for both the drain and fill plugs?

Yes, on most compatible models, the same gasket is used for both the lower magnetic drain plug and the upper vent/fill plug.

How tight should I tighten the drain plug?

Always tighten to the torque specified in your engine's service manual. Overtightening can damage the plug, gasket, or gearcase housing, while under-tightening can lead to leaks. If unsure, consult a professional mechanic.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). It has been built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, it is batch-inspected for consistency.

Shipping speed & cost?

We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options 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 support with your order details. Returns are accepted within our standard window for unused items in 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 part, 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.

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