Mercury – Quicksilver 816431A1 U-Joint Bellows | MerCruiser Alpha One Gen II & Vazer Sterndrives | 816431A1

Overview

The Quicksilver 816431A1 U-Joint Bellows keeps the heart of your drive system sealed tight. Designed for MerCruiser Alpha One Gen II (1991 and newer) and Vazer sterndrives, this flexible bellows keeps water out of the bell housing and protects the U-joints from corrosion and damage.

Made from durable, ribbed composite material, it flexes with your drive’s movement while maintaining a watertight seal. The kit includes clamps for both ends and installs easily with basic tools — a straightforward weekend project that keeps your boat running dry and trouble-free.

Key Features

• Purpose: Prevents water from entering the bell housing and damaging the U-joints or gimbal bearing.
• Fitment: For MerCruiser Alpha One Gen II (1991 and newer) and Vazer sterndrives.
• Construction: Flexible, ribbed composite material resists cracking, tearing, and UV damage.
• Ease of Install: Includes stainless-steel hose clamps for both ends; installs with common tools.
• OEM Quality: Built to Mercury Marine factory specs for perfect fit and long service life.

Engine & Boat Compatibility

• MerCruiser Alpha One Gen II sterndrives (1991 and newer)
• Vazer sterndrives
• Common on cruisers, runabouts, and fishing boats using MerCruiser power

Performance & Practical Benefits

A cracked or loose bellows can let water leak into the drive, leading to rusted U-joints or a ruined gimbal bearing. The 816431A1 forms a tight, flexible seal that moves with the drive as you trim or steer, keeping water out and grease in.

The ribbed design allows full range of motion without collapsing or binding, and the composite rubber material holds its shape even after years of exposure to heat, salt, and vibration. Replacing this seal is quick, inexpensive insurance against costly lower-unit repairs later.

Why Buy OEM

Mercury’s OEM bellows are molded from marine-grade compounds that outperform the thin rubber used in aftermarket copies. They fit correctly, clamp down evenly, and stay watertight through seasons of use.

An authentic Quicksilver bellows gives you the same reliability your sterndrive had when it left the factory — the right size, the right flexibility, and protection you can count on.

FAQ

Q1: Which drives fit the Quicksilver 816431A1 bellows?
A: It’s designed for MerCruiser Alpha One Gen II (1991 and newer) and Vazer sterndrives.

Q2: What’s included in the kit?
A: The U-joint bellows and two stainless-steel hose clamps for secure installation.

Q3: Can I install it myself?
A: Yes. With basic tools and your service manual, it’s an easy do-it-yourself replacement.

Q4: How often should I replace it?
A: Inspect the bellows every season and replace it if you find cracks, soft spots, or water inside the housing.

Q5: Why choose OEM?
A: OEM bellows use stronger, longer-lasting material and fit perfectly, keeping your drive sealed and protected.