Complete MerCruiser Alpha One Gen II Bellows Kit 4-Piece Set (74639Q02 + 816431A1 + 18654A1 + 27-94996Q2) - Shift Cable/U-Joint/Exhaust Bellows + Bell Housing Gasket Kit - Fits 1991 & Newer Models

Complete MerCruiser Alpha One Gen II Bellows Maintenance Kit

This comprehensive bellows maintenance kit is engineered for MerCruiser Alpha One Generation II sterndrive systems (1991 and newer). It provides a complete 4-component sealing solution, with each part manufactured to meet or exceed OEM specifications. The kit includes replacements for shift cable, U-joint, and exhaust bellows, plus a full bell housing gasket set.

Constructed from marine-grade rubber compounds and stainless steel hardware, these components are designed to withstand harsh saltwater and freshwater environments. This kit offers a cost-effective solution for performing a complete sterndrive service, ensuring all parts are compatible and preventing water intrusion into critical engine systems.

• Fits: MerCruiser Alpha One Gen II (1991-Present) and select R/MR Series (1983-1990).
• Directly replaces part numbers: 74639Q02, 816431A1, 18654A1 / 8M0124227, and 27-94996Q2.
• This is a complete 4-part kit containing one of each: Shift Bellows, U-Joint Bellows, Exhaust Bellows, and a Bell Housing Gasket Kit.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM andbrands.

Compatible Engine Models

Confirm your engine model/year in the table below.

MerCruiser Alpha One Gen II (1991-Present)

Serial Number Ranges: 1991-1995 (0D469859-0F679999), 1996-1997 (0F680000-0K999999), 1998 & Up (0L100040+)

MerCruiser R/MR Series (1983-1990)

Serial Number Requirement: 6225577 and higher

• 165 HP (2.5L 4-Cylinder)
• 170 HP (3.7L 4-Cylinder)
• 190 HP (4.3L V6)
• 260 HP (5.7L V8)

Additional Compatible Systems

• Vazer Sterndrive Systems (U-Joint Bellows 816431A1 component only)
• Bravo I, II, III & Blackhawk (Selected components may be compatible - consult technical support)

Technical Specifications

Package Contents

• 1x 74639Q02 - Shift Cable Bellows Assembly with 2 Stainless Steel Hose Clamps
• 1x 816431A1 - U-Joint Bellows Assembly with Grounding Straps and Clamps
• 1x 18654A1 / 8M0124227 - Exhaust Bellows Assembly with 2 Stainless Steel Hose Clamps
• 1x 27-94996Q2 - Bell Housing Installation Gasket Kit (6-piece set)

Installation Guide

1. Preparation: Cool the engine completely. Place the shift control in the forward gear position.
2. Sterndrive Removal: Disconnect the trim cylinders and remove the six 5/8" nuts securing the sterndrive to the bell housing. Carefully pull the sterndrive unit away. Always use a new mounting gasket upon reassembly.
3. Bell Housing Removal: Disconnect the shift cable inside the boat. A specialized hinge pin tool is required to remove the two hinge pins. Preserve the fiber washers.
4. Component Removal: Remove the old exhaust bellows, water hose, shift cable bellows, and U-joint bellows.
5. Surface Cleaning: Thoroughly clean all gimbal and bell housing flange surfaces where the new bellows will be seated.
6. Adhesive Application: Apply a marine-grade bellows adhesive (mandatory for the U-joint bellows) to the inner lips of the new bellows and the housing flanges.
7. Bellows Installation: Install the grounding straps on the U-joint bellows. Install the bell housing end first, then the gimbal housing end for each bellows.
8. Clamp Installation: Secure all new bellows with new stainless steel hose clamps and tighten to specification.
9. Gasket Installation: Ensure surfaces are clean and oil-free. Install the correct gaskets from the kit in the proper sequence as per your service manual.
10. Reassembly: Carefully guide the bell housing and sterndrive back into position, securing with hinge pins and all mounting nuts.
11. Final Connections: Reinstall the trim cylinders and all other disconnected components.
12. Final Testing: Once assembled, check for any water or oil leaks. Verify smooth shifting through all gears before operating the vessel.

Troubleshooting & FAQ

How do I confirm this kit fits my MerCruiser sterndrive?

This kit is specifically for MerCruiser Alpha One Gen II drives manufactured from 1991 to the present. You should verify your drive's serial number falls within the ranges listed in our compatibility chart (e.g., 0D469859 and up). It also fits some older R/MR series drives (1983-1990) with a serial number of 6225577 or higher. When in doubt, compare the part numbers to your service manual.

Is bellows adhesive required for installation?

Yes. Applying a suitable marine bellows adhesive is absolutely mandatory for the U-joint bellows (816431A1). This step is critical to creating a durable, watertight seal. Failure to use adhesive on this component will likely lead to water intrusion and severe damage to the gimbal bearing and U-joints.

How often should I replace the bellows in this kit?

Under normal freshwater or intermittent saltwater use, a replacement interval of 3-5 years is recommended. For boats used heavily in saltwater or kept in the water year-round, a more conservative interval of 2-3 years is advised for preventive maintenance. Replace the entire kit immediately if you discover any cracks, tears, or signs of water leakage.

What are the common signs of a failing bellows?

The most critical sign is finding water in your bilge, which could indicate a failed U-joint bellows. Other symptoms include difficulty or grinding when shifting gears (failed shift cable bellows), or abnormal exhaust sounds and potential water backflow (failed exhaust bellows).

OEM vs. Aftermarket?

This listing is anreplacement 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.

How fast do you ship and how much does it cost?

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.

What is your warranty and return policy?

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 anreplacement 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.