Magnetic Drain Plug Kit – Fits Mercury MerCruiser & Outboard Lower Units
This magnetic drain plug kit is designed for use on a wide range of Mercury/Mariner Outboards and MerCruiser Sterndrive lower units. It provides a direct-fit replacement for all compatible models that utilize a 3/8-16 UNC threaded magnetic drain and fill plug, helping to protect your gears by collecting metallic debris from the gear lube.
This kit is a direct replacement for Mercury part numbers 22-67892A06 and 8M0058389. It also cross-references with parts from GLM, Mallory, Redline, Pro Marine, and Sierra.
- Includes one magnetic drain/fill screw and one seal/washer for a complete installation.
- Features a strong embedded magnet to capture metal shavings and monitor gear health.
- Engineered with a 3/8-16 UNC thread size for a precise fit on specified models.
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
| Brand |
Part Number |
| Mercury |
22-67892A06 |
| Mercury |
8M0058389 |
| GLM |
21731 |
| Mallory |
9-72651 |
| Redline |
RL2375 |
| Pro Marine |
64892 |
| Sierra |
18-2375 |
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.
| Brand |
Model |
OEM Part No. |
Notes |
| MerCruiser |
Alpha Gen 1 |
22-67892A06 |
|
| MerCruiser |
Alpha Gen 2 |
22-67892A06 |
|
| MerCruiser |
R, MR, TR, TRS |
22-67892A06 |
|
| Mercury |
All Outboards with magnetic drain/fill plugs |
22-67892A06 |
Except Verado series |
Technical Specifications
| Specification |
Value |
| Product Type |
Magnetic Gearcase Drain Plug with Seal |
| Installation |
Lower Unit Gear Lube Drain & Fill Ports |
| Connection |
3/8-16 UNC Thread |
| Housing Material |
Metal with embedded magnet |
| Housing Color |
Silver/Metallic |
| Fitting Type |
Threaded plug with washer/seal |
| Thread Size |
3/8-16 UNC |
| Other Technical Attributes |
Strong embedded magnet designed to collect metal shavings |
Package Contents
-
1 x Magnetic Gear Lube Drain/Fill Screw (Replaces 22-8M0058389)
-
1 x Seal/Washer Gasket
Installation Guide
- Place a suitable drain pan underneath the lower unit of your engine.
- Using a large flathead screwdriver, carefully remove both the upper (vent) and lower (drain) gearcase screws.
- Allow the gear lube to drain out completely. Examine the old oil for any signs of water intrusion (milky appearance) or excessive metal particles.
- Clean the threads of the drain and vent holes on the gearcase.
- Install the new magnetic drain screw with its new seal into the lower drain hole. Tighten it until snug, but be careful not to overtighten and strip the threads.
- Using a gear lube pump, fill the gearcase through the lower drain hole until fresh lube begins to flow out of the upper vent hole.
- Reinstall the upper vent screw with its seal first, then quickly remove the lube pump and reinstall the lower drain screw.
- Wipe the lower unit clean of any excess lube and inspect both plugs for leaks after a few minutes.
Troubleshooting & FAQ
Q: How do I confirm this plug fits my engine?
A: This plug is designed for Mercury and MerCruiser lower units that use a 3/8-16 UNC threaded magnetic plug. Please check the part number cross-reference table and compatible engine list. Verifying the thread size of your current plug is the best way to ensure compatibility if you are unsure.
Q: What is the benefit of a magnetic drain plug?
A: The powerful embedded magnet attracts and collects fine ferrous metal particles circulating in your gear lube. Inspecting the magnet during lube changes provides an early warning of excessive gear wear or potential component failure.
Q: How often should I replace the drain plug seal?
A: The gasket/seal should be replaced every time you change your gear lube. This ensures a proper, leak-free seal and prevents water from entering your gearcase. The plug itself should last for many years but should be replaced if the magnet is weak or the threads are damaged.
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.