Lower Unit Drain Screw Gasket – Fits Mercury/Mercruiser (Replaces 12-19183-3, 12-19183K02, 12-19183Q02)

Lower Unit Drain Screw Gasket – Fits Mercury/Mercruiser (Replaces 12-19183-3, 12-19183K02, 12-19183Q02)

This replacement lower unit drain screw gasket is designed for Mercury Marine outboard and MerCruiser stern drive engines. It fits all horsepower models that are equipped with 3/8-16 drain/fill screws, ensuring a secure seal to prevent gear lube leakage.

This part is a direct replacement for Mercury Marine part numbers 12-19183-3, 12-19183K02, and 12-19183Q02, as well as Sierra 18-2244.

• Fits all Mercury and MerCruiser engines with 3/8-16 drain/fill screws (excluding Japanese-origin models).
• Made from durable blue plastic to ensure a tight, reliable seal.
• Package includes 12 individual drain screw gaskets.

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.

Technical Specifications

Package Contents

• 12 x Drain Screw Gasket (Replaces 12-19183-3, 12-19183K02, 12-19183Q02)

Installation Guide

1. Position a suitable drain pan under the lower unit of your engine.
2. Using a large flathead screwdriver, carefully remove the lower drain/fill screw.
3. Remove the upper vent screw to allow air to enter, which helps the gear lube to drain completely.
4. Inspect the magnetic tip of the drain screw for any metal shavings, as this can indicate internal gear wear.
5. Clean the drain screw threads thoroughly and remove the old gasket.
6. Slide the new plastic drain screw gasket onto the screw.
7. Once all the old gear lube has drained, reinstall the lower drain screw with the new gasket. Tighten it until snug, but do not overtighten.
8. Fill the lower unit with the manufacturer-recommended gear lube through the upper vent hole until fluid begins to flow out.
9. Install the upper vent screw with its gasket and tighten securely.
10. Clean any excess oil and check for leaks around both screws after a few minutes.

Troubleshooting & FAQ

Q: How do I confirm this gasket fits my engine?
A: This gasket fits all Mercury and MerCruiser outboard and sterndrive models that use a 3/8-16 lower unit drain and fill screw. It does not fit certain legacy models of Japanese origin. Please verify your engine's screw size before ordering.

Q: Why is it important to replace this gasket?
A: The drain screw gasket provides a critical seal that prevents gear lube from leaking out and water from entering the lower unit. A worn or cracked gasket can lead to catastrophic gearcase failure.

Q: How often should I replace these gaskets?
A: It is best practice to use a new gasket every time you change your lower unit gear lube. This is typically recommended once per season or every 100 hours of operation, whichever comes first.

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.