Gearcase Drain Plug Gasket – Fits Mercury/Mariner Outboards & MerCruiser Stern Drives (Replaces 26-830749, 8M0204693)

Gearcase Drain Plug Gasket – Fits Mercury/Mariner Outboards & MerCruiser Stern Drives (Replaces 26-830749, 8M0204693)

This gearcase drain plug gasket ensures a secure seal for Mercury/Mariner outboards and MerCruiser stern drives. It is specifically designed for models with 3/8-16 gearcase drain/fill screw holes, including the 115FS and 150 EFI 4-Stroke outboards.

This part is a direct replacement for Mercury OEM part numbers 26-830749 and the current supersession 8M0204693, offering a reliable fit and performance for lower unit maintenance.

• Material: Constructed from durable rubber-coated stainless steel for a long-lasting, leak-proof seal.
• Installation: The washer is placed between the gearcase drain/fill plug and the gearcase housing.
• Package Includes: A convenient 10-pack to have spares on hand for multiple services.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Mercury/Mariner Outboards

MerCruiser Stern Drives

Technical Specifications

Package Contents

• 10 x Gearcase Drain Plug Seal Washer Gaskets (Replaces 26-830749/8M0204693)

Installation Guide

1. Position a suitable drain pan under the lower unit gearcase.
2. Using a large, flathead screwdriver, carefully remove both the upper (vent) and lower (drain) screw plugs from the gearcase.
3. Allow all the old gear lube to drain out completely. Inspect the fluid for a milky appearance (indicating water intrusion) or metal shavings.
4. Thoroughly clean the magnetic tip and threads of both the drain and vent plugs.
5. Remove and discard the old gaskets from each screw plug.
6. Install a new 26-830749 / 8M0204693 gasket onto each of the two plugs.
7. Attach your gear lube pump to the lower drain screw hole.
8. Pump new gear lube into the gearcase until it begins to seep out of the upper vent screw hole.
9. Reinstall the upper vent screw plug with its new gasket first. Tighten it securely, but do not overtighten.
10. Quickly remove the lube pump fitting and reinstall the lower drain screw plug with its new gasket. Tighten securely.
11. Wipe the gearcase clean and inspect both plugs for any signs of leaks.

Troubleshooting & FAQ

Q: How do I know if this gasket fits my Mercury engine?
A: This gasket is designed for all MerCruiser stern drives and Mercury/Mariner outboards with 3/8-16 gearcase drain/fill screw holes, including models like the 115FS and 150 EFI 4-Stroke. Always check your engine's service manual or the old part number to confirm compatibility.

Q: What is the difference between this part and the original Mercury gasket?
A: This is an aftermarket replacement for OEM parts 26-830749 and the current supersession 8M0204693. It is made from high-quality rubber-coated stainless steel to meet original specifications for a reliable, long-lasting seal.

Q: How often should I replace the gearcase drain gaskets?
A: It is best practice to replace the drain and fill plug gaskets every time you change your lower unit gear lube. This helps prevent water intrusion and costly gearcase damage.

Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.