Lower Unit Drain Plug Gaskets – Fits Mercury/Mariner Outboard and MerCruiser Sterndrives (Replaces 12-19183, 12-19183Q02)

Lower Unit Drain Plug Gaskets – Fits Mercury/Mariner Outboard and MerCruiser Sterndrives (Replaces 12-19183, 12-19183Q02)

These lower unit drain plug gaskets are designed for Mercury/Mariner outboard engines and MerCruiser sterndrives featuring 3/8-16 drain/fill screw holes. Suitable for 4-Stroke and select 2-Stroke models, they provide a reliable seal for your engine's lower unit drain and fill screws.

Direct replacements include Mercury part numbers 12-19183-3, 12-19183Q02, 12-19183K02, and various aftermarket equivalents such as Sierra 18-2244, Sierra 18-2245, SEI Marine 98-102-09, Mallory 9-60101, Mallory 9-60102, GLM 31170, and OBR Red Rhino MR-103.

• Includes multiple gaskets per package depending on brand
• Fits 3/8-16 drain/fill screw holes
• Single-use; replace with every gear oil change

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

• 10 x Lower Unit Drain Plug Gaskets (12-19183-3/12-19183Q02) - JLM Marine variant
• 12 x Lower Unit Drain Plug Gaskets (12-19183-3/12-19183Q02) - GHOONEY variant
• 20 x Lower Unit Drain Plug Gaskets (12-19183-3/12-19183Q02) - GHmarine variant
• 30 x Lower Unit Drain Plug Gaskets (12-19183-3/12-19183Q02) - BOLEWIN variant

Installation Guide

1. Drain the gear oil from the lower unit completely before removing the drain plug gasket.
2. Carefully remove the old drain plug gasket to avoid damage to the drain/fill screw or sealing surface.
3. Clean the drain/fill screw hole area thoroughly of any debris, oil, or old sealing material.
4. Place the new gasket onto the drain/fill screw, ensuring proper alignment to the screw threads.
5. Install the screw with the new gasket back into the lower unit drain/fill hole and tighten securely.
6. Refill the lower unit with fresh gear oil to the manufacturer’s recommended level.
7. Check for leaks around the drain plug after installation and during initial engine operation.

Troubleshooting & FAQ

• How do I confirm this fits my engine? Confirm your engine model/year in the compatible engine table and check for 3/8-16 drain/fill screw holes on your Mercury/Mariner or MerCruiser engine.
• How often should I replace the drain plug gasket? Replace the gasket with every gear oil change to maintain a proper seal and prevent leaks.
• What are the main differences compared to OEM parts? This is an aftermarket replacement built to OEM specifications using comparable-grade materials.
• What are common signs the gasket needs replacement? Visible wear, deformation, or leaks around the drain plug area indicate a need for replacement.
• 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.