U-Joint Bellows for MerCruiser Alpha One Gen II & Vazer Sterndrives – Replaces Mercury 816431A1
U-Joint Bellows for MerCruiser Alpha One Gen II & Vazer Sterndrives – Replaces Mercury 816431A1 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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U-Joint Bellows for MerCruiser Alpha One Gen II & Vazer Sterndr...
U-Joint Bellows for MerCruiser Alpha One Gen II & Vazer Sterndrives – Replaces Mercury 816431A1 is backordered and will ship as soon as it is back in stock.
Product Details
This flexible, ribbed composite U-joint bellows is designed for MerCruiser Alpha One Gen II sterndrives from 1991 and newer, as well as Vazer sterndrives. It helps prevent water from entering through the bell housing and protects the u-joint area from water intrusion.
This is an aftermarket replacement for Mercury/Quicksilver OEM part number 816431A1. It is also cross-referenced with Sierra 18-2747, SEI Marine 9A-116-02K, OBR MR-909, Mallory Marine 9-72704, and GLM 89180.
- Designed for MerCruiser Alpha One Gen II and Vazer sterndrives.
- Flexible, ribbed composite bellows construction.
- Helps keep water out of the bell housing and away from u-joint components.
- Sold as one replacement u-joint bellows.
Part Number Matrix
Use the following manufacturer and aftermarket references to compare the replacement part with your existing bellows.
| Brand | Part Number |
|---|---|
| Mercury/Quicksilver OEM | 816431A1 |
| Sierra Marine | 18-2747 |
| SEI Marine | 9A-116-02K |
| OBR | MR-909 |
| Mallory Marine | 9-72704 |
| GLM | 89180 |
Engine & Model Compatibility
Confirm the sterndrive model and application before ordering. The fitment supplied for this bellows is limited to the applications listed below.
| Brand | Sterndrive Model | Years | OEM Reference | Application |
|---|---|---|---|---|
| MerCruiser | Alpha One Gen II | 1991 and newer | 816431A1 | U-joint bellows |
| MerCruiser | Vazer | All listed Vazer applications | 816431A1 | U-joint bellows |
This listing is not identified for Alpha One Gen I, Bravo, or other sterndrive models. Verify the drive generation and the part number on your original component before ordering.
Technical Specs
- Product Type
- U-joint bellows
- Application
- MerCruiser Alpha One Gen II and Vazer sterndrives
- Fitment Year
- Alpha One Gen II: 1991 and newer
- Construction
- Flexible, ribbed composite bellows
- Function
- Helps prevent water from entering through the bell housing
- Replacement Reference
- Mercury/Quicksilver 816431A1
- Product Type
- Single replacement bellows, not a complete installation kit
What’s in the Box
- 1 x U-joint bellows
Clamps, clips, sleeves, adhesive, and other installation hardware are not confirmed as included with this single bellows listing. Reuse only serviceable hardware or obtain any required installation components separately.
Installation Notes
- Secure the vessel and follow all applicable marine service-safety procedures.
- Place the sterndrive in the position specified by the service manual and remove the drive assembly as required for bellows access.
- Remove the old bellows and inspect the bell housing, gimbal housing, clamps, and surrounding components for corrosion, damage, or wear.
- Thoroughly clean and dry the mounting surfaces before installing the replacement bellows.
- Install the bellows in the correct orientation and seat both ends fully on their mounting surfaces.
- Secure the bellows using suitable serviceable clamps and follow the sterndrive manufacturer’s service-manual specifications for clamp position and tightening.
- Reinstall the sterndrive, check alignment and clearance, and inspect the installation for a secure seal before operating the boat.
Installation requires sterndrive removal and should be performed by a qualified marine technician or by someone using the correct service information and tools.
Troubleshooting & FAQ
How do I know if my u-joint bellows needs replacement?
Inspect the bellows for cracks, tears, hardening, distortion, or other deterioration. Water or corrosion in the bell housing or around the u-joint and gimbal-bearing area can indicate a failed or leaking bellows and should be investigated before further operation.
What maintenance is recommended?
Inspect the bellows regularly and at least during annual servicing. Replace it immediately if any cracking, tearing, brittleness, leakage, or other damage is found. Follow the sterndrive manufacturer’s service schedule for inspection and replacement intervals.
Will this fit sterndrives other than Alpha One Gen II and Vazer?
The supplied fitment identifies MerCruiser Alpha One Gen II sterndrives from 1991 and newer and Vazer sterndrives. Fitment for Alpha One Gen I, Bravo, or other drives is not confirmed. Verify your drive model and original part number before ordering.
What can happen if a u-joint bellows fails?
A damaged bellows can allow water into the bell housing and may lead to corrosion or damage of the u-joint, gimbal bearing, and related components. Stop operation and inspect the drive if water intrusion or bellows damage is suspected.
Do I need special tools for installation?
Because the sterndrive normally must be removed, installation may require a suitable socket set, torque wrench, alignment equipment, and bellows-specific tools depending on the drive and service procedure. Consult the applicable service manual before beginning work.
Is this an OEM Mercury part?
No. This is an aftermarket replacement bellows intended for applications using Mercury/Quicksilver 816431A1 as the replacement reference.
Safety & Important Information
- Verify the sterndrive model, generation, year range, and original part number before ordering.
- This is a single replacement u-joint bellows, not a complete bellows installation kit.
- Clamps and other installation hardware are not confirmed as included; check the contents of your order before starting installation.
- Professional installation is recommended because sterndrive removal and alignment may be required.
- Do not operate the vessel if the bellows is cracked, torn, leaking, or improperly seated.
About Sea Sierra
- Marine Replacement Parts — We supply replacement components for common marine engine and sterndrive service applications.
- Application-Focused Listings — Product descriptions identify the supported models and replacement references available for each part.
- Practical Service Support — Always verify your original component and consult the applicable manufacturer service information before installation.
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