Transom Seal Repair Kit – Fits Mercury/MerCruiser Alpha One Gen 1, R, MR (Replaces 30-803097T1)
Transom Seal Repair Kit – Fits Mercury/MerCruiser Alpha One Gen 1, R, MR (Replaces 30-803097T1) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Transom Seal Repair Kit – Fits Mercury/MerCruiser Alpha One Gen 1, ...
Product Details
This comprehensive Transom Seal Repair Kit – Fits Mercury/MerCruiser Alpha One Gen 1, R, MR (1983-1990) (Replaces 30-803097T1) provides all the necessary components to service the bellows and gimbal bearing. It is designed for MerCruiser R, MR, and Alpha One Generation 1 sterndrives manufactured from 1983 to 1990 (Serial Number 6225577 & UP) and Alpha One SS models from 1986–1989 (Serial Number 0A545004 & UP).
This kit serves as a direct interchange for Mercury/MerCruiser 30-803097T1, Sierra 18-8213/18-2601, GLM 21950, and Mallory 9-72902.
- Installs as a direct OEM-style replacement.
- Includes a complete set of bellows, transom gaskets, and the gimbal bearing.
- Comes with both 3/4" and 5/8" water hoses to fit various configurations.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/MerCruiser | 30-803097T1 |
| Sierra | 18-8213 / 18-2601 |
| GLM | 21950 |
| Mallory | 9-72902 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Years | OEM Part No. | Notes |
|---|---|---|---|---|
| MerCruiser | R Drive (Pre-Alpha One) | 1976–1983 | 30-803097T1 | |
| MerCruiser | MR Drive (Pre-Alpha One) | 1976–1983 | 30-803097T1 | |
| MerCruiser | Alpha One | 1983–1990 | 30-803097T1 | Serial Number 6225577 & UP |
| MerCruiser | Alpha One SS | 1986–1989 | 30-803097T1 | Serial Number 0A545004 & UP |
Technical Specs
- Product Type
- Transom Seal/Bellows Repair Kit
- Installation
- Direct OEM replacement
- Compatibility
- R, MR, Alpha 1 (1983-90) S/N 6225577 & UP, Alpha 1 SS (1986-89) S/N OA545004 & UP
- Housing Material
- Marine-grade rubber
- Contents
- Complete bellows kit with gimbal bearing
- Water Hose Size
- Includes both 3/4" and 5/8" hoses
- Weight
- 2.45 kg (5.4 lb)
- Warranty
- 1-year against manufacturing defects (aftermarket)
- Other Technical Attributes
- Includes stainless steel hose clamps as required
What’s in the Box
- 1 x U-Joint Bellows (60932A4)
- 1 x Exhaust Bellows (18654A1)
- 1 x Shift Cable Bellows (74639)
- 1 x Water Hose 3/4" (32-41725-33)
- 1 x Water Hose 5/8" (32-32461)
- 1 x Gimbal Bearing (30-60792A4)
- 1 x Gasket Kit (27-94996T2)
- 1 x Set of Stainless Steel Hose Clamps
Installation Notes
- Ensure the engine is off, the battery is disconnected, and the sterndrive is in the full down (trimmed in) position.
- Remove the sterndrive assembly from the bell housing according to your official service manual.
- Carefully detach and remove the old U-joint, exhaust, and shift cable bellows from the transom assembly. Note the orientation of all clamps.
- Using a slide hammer and puller attachment, extract the old gimbal bearing from the bell housing.
- Thoroughly clean all mating surfaces, removing any old adhesive, sealant, or corrosion.
- Install the new gimbal bearing using a dedicated bearing installation tool, ensuring it is seated correctly and the lubrication hole is aligned.
- Install the new shift cable bellow, U-joint bellow, and exhaust bellow. Secure them with new stainless steel clamps.
- Attach the new 3/4" or 5/8" water hose as required for your application.
- Fit the new gaskets and O-rings from the kit onto the transom assembly.
- Reinstall the sterndrive, torquing all fasteners to the manufacturer’s specified values. Check for smooth movement and proper shift cable operation.
Troubleshooting & FAQ
Will this kit fit an Alpha One Gen 2 drive?
No, this kit is specifically designed for MerCruiser R, MR, and Alpha One Gen 1 sterndrives (1983–1990). Alpha One Gen 2 drives require a different bellows and bearing kit.
What are the signs that my transom seals need replacing?
Common symptoms of failing bellows or gimbal bearing include water entering the boat's bilge area, a roaring or grinding noise from the transom when turning or trimming the drive, or visible cracking and brittleness in the rubber bellows during inspection.
How often should bellows be replaced?
As a preventative maintenance measure, it is recommended to inspect bellows annually for cracks or wear and replace them every 3–5 years, depending on usage and environmental conditions (saltwater vs. freshwater).
Do I need special tools for this job?
Yes, installation typically requires specialized tools, including a gimbal bearing installation/removal tool, a hinge pin tool to remove the bell housing, and bellows expander and adhesive tools. Professional installation is highly recommended.
Is this an OEM kit or an aftermarket one?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials and manufactured in an ISO 9002 facility, with batch inspections for consistency.
How fast is shipping?
We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free, and expedited options may appear at checkout where available.
What is the warranty and return policy?
The kit is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter an issue, contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. Please see our policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part before purchasing. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement component, not an OEM part.
- Professional installation is recommended for safety and optimal performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or quality control.
Payment & Security
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