Transom Seal Repair Kit – Fits MerCruiser Alpha One Generation II (Replaces 803099T1)

Transom Seal Repair Kit – Fits MerCruiser Alpha One Generation II (Replaces 803099T1)

This transom seal repair kit provides the essential components needed to reseal the transom assembly on MerCruiser Alpha One Generation II sterndrive units manufactured between 1991 and 1997 with serial numbers ranging from 0D469859 to 0K999999.

It serves as a direct replacement for multiple OEM and aftermarket part numbers, including Mercury/Quicksilver 30-803099T1, Sierra 18-8206-1 (Greasable), and Sierra 18-8218 (Sealed).

• Complete Reseal Solution: Includes U-Joint, exhaust, and shift cable bellows, gimbal bearing, gaskets, and water hoses required for a full transom service.
• Precise Fitment: Engineered specifically for the Alpha One Gen II sterndrive bell housing and transom interface.
• Durable Materials: Constructed with high-quality rubber bellows, stainless steel clamps, and brass/metal fittings to withstand the marine environment.

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 Assembly (816431A1)
• 1 x Exhaust Bellows Assembly (18654A1/8M0124227)
• 1 x Bearing Assembly (30-862540A3/30-879194A01)
• 1 x Shift Cable Bellows Assembly (74639A2)
• 1 x Water Hose (32-4172533/32-8M0062309)
• 1 x Alpha Outdrive Mounting Gasket Kit (27-94996Q2)
• 1 x Gasket (27-8M0091545) (per MercruiserParts.com)
• 1 x Hose - .250 ID x .50 OD x 9.50 LG (32-8M0062593) (per MercruiserParts.com)
• 1 x Hose Water (32-8M0109048) (per MercruiserParts.com)

Installation Guide

1. Ensure the sterndrive is trimmed all the way down and disconnect the battery.
2. Following the manufacturer's service manual, carefully remove the sterndrive unit from the bell housing.
3. Remove the old U-joint, exhaust, and shift cable bellows. Use a slide hammer or bearing puller to extract the old gimbal bearing.
4. Thoroughly clean all mating surfaces on the transom assembly, removing any old sealant, adhesive, or gasket residue.
5. Use a bearing driver to install the new gimbal bearing into the gimbal housing.
6. Install the new bellows, ensuring they are properly seated and secured with the provided clamps. A bellows expander tool is highly recommended for this step.
7. Replace the main water hose and any other included hoses or gaskets.
8. Apply sealant to the new mounting gaskets and reinstall the sterndrive assembly. Torque all fasteners to the manufacturer's specifications.
9. Reconnect the shift cable and verify proper operation. Once reassembled, check for water leaks before operating the vessel.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my engine?

A: This kit is specifically for MerCruiser Alpha One Generation II sterndrives made from 1991–1997. The most reliable way to confirm fitment is to check if your sterndrive's serial number falls within the range of 0D469859 to 0K999999.

Q: What are the common signs that my transom seals are failing?

A: The most common signs include finding water in your boat's bilge, hearing a roaring or grinding noise from the transom area (indicating a bad gimbal bearing), or seeing visible cracks and deterioration on the rubber bellows during inspection.

Q: How often should I replace my transom bellows?

A: It is recommended to inspect bellows annually for any signs of cracking, dry rot, or holes. As a preventative maintenance measure, transom seals and bellows should typically be replaced every 3-5 years, depending on usage, storage, and water conditions (saltwater vs. freshwater).

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.