Magnetic Drain Plug – Fits Mercury & MerCruiser Outboards & SternDrives (Replaces 8M0058389, 67892A1)

Magnetic Drain Plug – Fits Mercury & MerCruiser Outboards & SternDrives (Replaces 8M0058389, 67892A1)

This magnetic lower unit drain and fill plug is designed for use on Mercury/Mariner outboards and MerCruiser sterndrives. It is compatible with all MerCruiser sterndrives, including Alpha One, Alpha One Gen II, MC-1, TR, and TRS models. It also fits Mercury and Mariner outboards equipped with 3/8-16 drain/fill hole screws, with the exception of the Verado series.

This component directly replaces Mercury/QuickSilver part number 8M0058389 and other equivalents from Sierra, GLM, and Mallory. The integrated magnet is a key feature, capturing metallic debris in the gear lube to protect internal components from excessive wear.

• Engineered with a strong magnet to catch ferrous metal particles, preventing gear damage.
• Features a 3/8-16 UNC threaded design with a pre-installed seal for leak-proof installation.
• Includes one magnetic drain/fill screw with a matching seal.

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.

MerCruiser

Mercury/Mariner

Technical Specifications

Package Contents

• 1 x Lower Unit Gear Lube Drain and Fill Hole Screw and Seal (8M0058389)

Installation Guide

1. Position a suitable drain pan underneath the lower unit's drain screw.
2. Using a large flathead screwdriver or appropriate tool, carefully remove the old lower drain/fill screw and the upper vent screw.
3. Allow all the old gear lube to drain completely from the lower unit. Note the color for signs of water intrusion (milky appearance).
4. Inspect the magnet on the old plug for excessive metal shavings, which could indicate gear wear.
5. Wipe the screw hole threads clean to ensure a debris-free surface for the new seal.
6. Install the new magnetic drain plug with its pre-installed seal into the bottom hole. Hand-tighten securely, but do not overtighten.
7. Pump new lower unit lubricant into the bottom hole until it flows out of the upper vent hole, ensuring no air pockets remain.
8. Re-install the top vent screw first, then quickly remove the lube filler tube and re-install the bottom drain plug. This minimizes oil loss.
9. Clean any excess lubricant from the gear case exterior and check for leaks after a short period.

Troubleshooting & FAQ

How do I know if this drain plug will fit my engine?

This plug fits all MerCruiser sterndrives and most Mercury/Mariner outboards with a 3/8-16 drain screw thread. It replaces part numbers 8M0058389, 67892A1, and others listed in the cross-reference table. It does not fit Verado series outboards. Always check your service manual or original part number to confirm compatibility.

What is the benefit of a magnetic drain plug?

The integrated magnet captures fine ferrous metal particles that circulate in your gear lube. This helps prevent premature wear and damage to your gears and bearings by removing these abrasive contaminants from circulation.

How often should I check or replace the drain plug seal?

The seal should be replaced every time you change your gear lube to prevent leaks. This plug comes with a new seal pre-installed for your convenience, ensuring a proper fit and saving you from having to source it separately.

OEM vs. Aftermarket?

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.

How fast do you ship and how much does it cost?

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.

What is your warranty and return policy?

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.