MerCruiser Alpha Gen 1 Bellows Repair Kit – Fits R, MR, Alpha One (1983-1990) Sterndrives (Replaces 30-803097T1)
MerCruiser Alpha Gen 1 Bellows Repair Kit – Fits R, MR, Alpha One (1983-1990) Sterndrives (Replaces 30-803097T1) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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MerCruiser Alpha Gen 1 Bellows Repair Kit – Fits R, MR, Alpha One (...
MerCruiser Alpha Gen 1 Bellows Repair Kit – Fits R, MR, Alpha One (1983-1990) Sterndrives (Replaces 30-803097T1) is backordered and will ship as soon as it is back in stock.
Product Details
This is a complete, OEM-quality MerCruiser Alpha Gen 1 Bellows Repair Kit designed for R, MR, and Alpha One Generation 1 sterndrives manufactured from approximately 1976 to 1990. The kit provides all essential seals and bearings to restore the transom assembly, preventing water intrusion and ensuring reliable operation.
This kit serves as a direct replacement for Mercury/MerCruiser part 30-803097T1 and interchanges with Sierra 18-8213, 18-2601, and GLM 21950.
- Engineered for direct OEM-replacement fitment.
- Includes a complete bellows kit with a new gimbal bearing.
- Comes with both 3/4" and 5/8" water hoses for broad compatibility.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/MerCruiser | 30-803097T1 |
| Sierra | 18-8213 |
| Sierra | 18-2601 |
| GLM | 21950 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This kit is designed specifically for pre-Alpha and Alpha series MerCruiser sterndrives within the specified serial number ranges.
| Brand | Model | Years | OEM Part No. | Notes |
|---|---|---|---|---|
| MerCruiser | R Drive | 1976–1983 | 30-803097T1 | Pre-Alpha One |
| MerCruiser | MR Drive | 1976–1983 | 30-803097T1 | Pre-Alpha One |
| MerCruiser | Alpha One | 1983–1990 | 30-803097T1 | S/N 6225577 & UP |
| MerCruiser | Alpha One SS | 1986–1989 | 30-803097T1 | S/N OA545004 & 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
- Included Components
- Complete bellows kit with gimbal bearing
- Water Hose Size
- Includes both 3/4" and 5/8" hoses
What’s in the Box
- 1 x U-Joint bellows assembly
- 1 x Exhaust Bellows
- 1 x Transom bell housing gasket set
- 1 x Water intake hoses (both 3/4" and 5/8" sizes)
- 1 x Shift Bellows
- 1 x Gimbal Bearing
- 1 x Set of stainless steel hose clamps as required
Installation Notes
- Disconnect the battery and place the sterndrive in the full "up" (trailer) position.
- Remove the sterndrive assembly according to your official service manual's procedure.
- Carefully cut and remove the old U-joint, exhaust, and shift cable bellows and their clamps.
- Remove the old gimbal bearing from the transom housing using a slide hammer or puller tool.
- Thoroughly clean all mating surfaces on the bell housing and transom assembly, removing any old sealant or debris.
- Install the new gimbal bearing using an appropriate driver, ensuring it is seated correctly.
- Fit the new U-joint, exhaust, and shift bellows, securing them with the new stainless steel clamps. Ensure they are fully seated and sealed.
- Choose and install the correct water hose (3/4" or 5/8") for your specific transom assembly.
- Reinstall the outdrive, carefully aligning the driveshaft and shift linkage. Torque all fasteners to the manufacturer's specified values.
- After reassembly, lower the drive, reconnect the battery, and test for any water leaks in a controlled environment before full operation.
Troubleshooting & FAQ
How do I know if this kit fits my sterndrive?
This kit fits MerCruiser R, MR, Alpha One (Gen 1) drives from 1983–1990 (Serial Number 6225577 & up), and Alpha One SS drives from 1986–1989 (S/N OA545004 & up). Always check your drive's model and serial number against the compatibility list before ordering.
What are the signs my bellows need replacing?
The most common signs of failing bellows are visible cracking, tearing, or dry-rot in the rubber. Other indicators include water entering your boat's bilge area or a rumbling/grinding noise from the transom, which often signals a failed gimbal bearing due to water intrusion.
How often should sterndrive bellows be replaced?
For preventative maintenance, it is recommended to inspect bellows annually for any signs of wear or damage. Full replacement is advised every 3–5 years, depending on usage frequency, storage conditions, and whether the boat is used in saltwater or freshwater.
Why are two different water hose sizes included?
During the production years covered by this kit, MerCruiser used both 3/4" and 5/8" inner diameter water intake hoses on their transom assemblies. We include both to ensure you have the correct size for your specific drive without needing a separate purchase.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
Safety & Important Info
- Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended for safety and 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 QC.
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