Mercury – Quicksilver Gear Housing Gasket | Lower Unit Seal | Marine Composite | 430331

Overview

A good seal means a healthy drive. The Mercury Marine 430331 Quicksilver Gear Housing Gasket keeps water out and gear oil in, ensuring your lower unit stays properly lubricated and protected. Built to factory specs, this gasket fits a wide range of Mercury, Mariner, and MerCruiser drives, including Alpha One Gen II sterndrives and 40–300HP outboards. Made from durable, marine-grade material, it’s designed to handle pressure, vibration, and temperature changes without shrinking or leaking — giving your gearcase the protection it needs to perform season after season.

Key Features

• Purpose: Seals the gear housing to prevent leaks and keep gear oil contained.
• Material: Made from marine-tested composite that resists heat, oil, and pressure.
• Performance: Maintains a watertight seal for reliable lubrication and corrosion prevention.
• Design: Precision-cut to Mercury OEM specifications for a perfect fit every time.
• Durability: Withstands marine stress, from high-speed vibration to heavy load conditions.
• Compatibility: Fits a wide range of MerCruiser and Mercury/Mariner outboards and sterndrives (see below).

Engine & Boat Compatibility

• MerCruiser Alpha One Gen II sterndrives
• Mercury/Mariner 40–60HP FourStroke BigFoot outboards
• Mercury 60HP (3-cylinder) BigFoot and 75–115HP TwoStroke (USA A996142+, BEL 9483121+)
• 75–115HP EFI FourStroke and 150HP EFI FourStroke outboards
• V-200 (3.0L) DFI outboards and 135–300HP Verado outboards
• V-225/250 (3.0L) outboards

This gasket is used across a variety of boats — from bass boats and pontoons to offshore cruisers — and is suitable for both freshwater and saltwater use.

Performance & Real-World Benefits

The 430331 gasket keeps your gear housing sealed tight, protecting critical internal components from water intrusion and gear oil loss. A strong, even seal ensures smooth operation, proper lubrication, and long-term reliability for your lower unit.

Over time, older gaskets can compress, harden, or fail under heat and vibration, allowing leaks that can lead to expensive damage. Replacing it during maintenance helps maintain peak performance and peace of mind — so you can focus on the water, not your gearcase.

Why Choose Mercury OEM

The Quicksilver 430331 is a genuine Mercury Marine part, made from materials tested for marine pressure and temperature extremes. Generic gaskets can warp, tear, or fail to line up with Mercury’s precision-machined surfaces.

OEM gaskets ensure proper sealing, exact fit, and long-term reliability — protecting your lower unit and maintaining your factory warranty. Mercury builds its gaskets to handle the harshest marine environments, giving your drive the same confidence it had when it was new.

FAQ

Q1: What engines and drives does this gasket fit?
It fits MerCruiser Alpha One Gen II, Mercury/Mariner 40–300HP outboards, and various EFI, DFI, and Verado models listed above.

Q2: What’s the gasket made from?
It’s made from a marine-grade composite designed to resist oil, heat, and pressure.

Q3: Why should I replace this gasket?
A worn or leaking gasket can allow water into the gearcase or cause oil loss — both can lead to serious damage.

Q4: Can it handle saltwater use?
Yes — it’s designed to perform in both salt and freshwater environments.

Q5: Why OEM instead of aftermarket?
Mercury OEM parts match the exact shape and strength of your drive housing, ensuring proper sealing and long-lasting protection.