Mercury – Lower Unit Drain and Fill Hole Screw Seals | Gearcase Component | Nylon and Rubber Composite | 19183K02

Overview

When it’s time to change your gear lube, a good seal is what keeps the water out and the oil in. The Mercury Marine 19183K02 Lower Unit Gear Lube Drain and Fill Hole Screw Seals are simple but essential parts that protect your drive from leaks and contamination. Designed to fit 3/8-16 drain and fill screws, these OEM gaskets ensure a perfect seal every time you service your gearcase. Sold in a pack of four, they’re built to fit all MerCruiser engines and most Mercury and Mariner outboards, giving you dependable protection every time you drain and refill.

Key Features

• Purpose: Provides a watertight seal for gear lube drain and fill screws.
• Material: Made from durable nylon and rubber composite for flexibility and long-lasting compression.
• Fitment: Designed for 3/8-16 drain/fill screws on Mercury and MerCruiser gearcases.
• Compatibility: Fits all MerCruiser engines and most Mercury and Mariner outboards, excluding Verado and Japanese-built models.
• Quantity: Includes four gaskets for multiple services or spare replacements.
• Performance: Prevents water intrusion and keeps gear lube from leaking during operation.

Engine & Boat Compatibility

• All MerCruiser sterndrives and inboards.
• Most Mercury and Mariner outboards (excluding Verado and engines of Japanese origin).
• Commonly used on runabouts, fishing boats, pontoons, and cruisers.
• Designed for freshwater and saltwater applications.

Performance & Practical Benefits

A proper seal around your drain and fill screws is critical for protecting gears and bearings. The 19183K02 seal set ensures your lower unit stays tight and dry. Each gasket is molded to compress evenly without cracking or deforming, even after repeated tightening and removal.

Replacing these seals with every gear lube change prevents leaks, keeps contaminants out, and extends the life of your oil and components. They’re small parts that make a big difference — quick to replace and worth every bit of peace of mind they provide.

Why Buy OEM

It’s tempting to reuse old seals, but that’s how water finds its way into your gear lube. The Mercury 19183K02 is a genuine OEM part, made from materials that maintain shape, flexibility, and sealing strength under real marine conditions. Aftermarket washers may be too stiff or the wrong thickness, leading to seepage or uneven compression.

With OEM Mercury seals, you’re guaranteed a perfect fit and a proper seal every time. It’s a small investment that protects your lower unit — and helps avoid expensive repairs later on.

FAQ

Q1: What engines do these seals fit?
They fit all MerCruiser drives and most Mercury/Mariner outboards, except Verado and Japanese-built models.

Q2: How many seals are included?
Each pack includes four OEM gaskets for 3/8-16 drain and fill screws.

Q3: Should I replace these every time I change gear lube?
Yes — always replace the seals during each gear lube service to maintain a proper watertight seal.

Q4: What are they made from?
They’re built from a tough nylon and rubber blend, designed for compression and durability.

Q5: Can they handle saltwater conditions?
Yes. The materials resist corrosion, swelling, and deterioration from salt exposure.