U-Joint Bellows – Fits MerCruiser Alpha One Gen II & Vazer Sterndrives (Replaces 816431A1)

U-Joint Bellows – Fits MerCruiser Alpha One Gen II & Vazer Sterndrives

This U-joint bellows assembly is designed for Mercury MerCruiser Alpha One Gen II (1991 and newer) and Vazer sterndrives. It serves as a direct replacement for the original equipment manufacturer (OEM) part, preventing water from entering the bell housing and protecting the critical u-joint and gimbal bearing components.

Engineered from flexible, durable composite rubber, this assembly meets OEM specifications for a precise fit and reliable performance. It provides a robust seal against the marine environment, ensuring the longevity of your sterndrive components.

• Engineered for a direct OEM replacement fit.
• Constructed from high-grade flexible composite rubber for durability.
• Comes as a complete kit with necessary installation hardware.

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

• 1 x U-Joint Bellows (Replaces 816431A1)
• 1 x Grounding Clip (54-86049)
• 1 x Worm Gear Clamp (54-815504372)
• 1 x Sleeve (816607)

Installation Guide

1. Safety First: Disconnect the battery and ensure the boat is stable and secure before beginning work.
2. Trim Drive: Tilt the sterndrive to the full "up" or "trailer" position to access the bellows.
3. Remove Old Bellows: Carefully cut and remove the old clamps and bellows. Inspect the bell housing and gimbal bearing for any signs of water intrusion or damage.
4. Clean Surfaces: Thoroughly clean the mounting grooves on both the bell housing and the gimbal housing to ensure a clean, debris-free sealing surface.
5. Install New Bellows: Apply a suitable bellows adhesive to the grooves. Fit the new bellows into place, ensuring it is properly seated.
6. Secure Clamps: Install and tighten the new hose clamps on both ends of the bellows to create a secure, watertight seal.

Troubleshooting & FAQ

Q: How do I confirm this fits my engine?

A: This bellows assembly is compatible with MerCruiser Alpha One Gen II sterndrives (from 1991 to present) and all MerCruiser Vazer sterndrives. Please verify that your original part number matches one listed in the cross-reference table, such as the primary OEM number 816431A1.

Q: What are the signs my u-joint bellows has failed?

A: Common signs of failure include visible cracks, splits, dry rot, or holes in the rubber. The most critical indicator is finding water inside the bellows area after removing the drive, which can lead to severe damage to the gimbal bearing and U-joints.

Q: How often should I replace the U-joint bellows?

A: We recommend visually inspecting the bellows at least once a season or every 50 hours of operation. As a preventative measure, it is wise to replace them every 3-5 years, depending on usage and water conditions (saltwater vs. freshwater), to avoid costly failures.

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.