Exhaust Bellows Kit – Fits MerCruiser Alpha One Gen 1 & 2, Bravo (Replaces 18654A1, 32734A3)
Exhaust Bellows Kit – Fits MerCruiser Alpha One Gen 1 & 2, Bravo (Replaces 18654A1, 32734A3) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
Worry-free returns
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).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Exhaust Bellows Kit – Fits MerCruiser Alpha One Gen 1 & 2, Brav...
Product Details
This Exhaust Bellows Kit provides a crucial seal for MerCruiser sterndrives, including Alpha One Gen 1 (1983–1990), Alpha One Gen 2 (1991–Present), and Bravo I, II, & III models. Made from flexible, durable rubber, it connects the transom assembly to the bell housing, preventing water from entering the vessel.
It serves as a direct replacement for MerCruiser part numbers 18654A1 and 8M0124227, and interchanges with Sierra 18-2750, GLM 89100, and UANOFCN 32734A3.
- Features a ribbed design for enhanced flexibility during steering and trimming.
- Connects the transom plate to the bell housing for a watertight seal.
- Includes the necessary worm gear clamps and grounding clips for a complete installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By | Notes |
|---|---|---|---|
| MerCruiser | 18654A1 | 8M0124227 | Original OEM part. |
| MerCruiser | 8M0124227 | Current OEM replacement. | |
| MerCruiser | 32734A3 | Referenced OEM part number. | |
| Sierra | 18-2750 | Aftermarket Equivalent | |
| GLM | 89100 | Aftermarket Equivalent | |
| UANOFCN | 32734A3 | Aftermarket Equivalent |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | Alpha One Gen 1 | All | 4-Stroke | 1983–1990 | 18654A1 | Serial Range: 6225577 & Up |
| MerCruiser | Alpha One Gen 2 | All | 4-Stroke | 1991–Present | 18654A1/8M0124227 | Serial Range: 0D469859 & Up; Superseded to 8M0124227 |
| MerCruiser | Bravo I/II/III | All | 4-Stroke | 1988–Present | 18654A1/8M0124227 | Serial Range: 0B664190 & Up |
| MerCruiser | Blackhawk | All | 4-Stroke | 1994–1995 | 18654A1 | Serial Range: 0F186717 & Up |
| MerCruiser | R / MR | All | 4-Stroke | 1983–1990 | 18654A1 | Serial Range: 6225577 & Up |
| MerCruiser | 120/140/160/165 | 120-165 | 4-Stroke | 1972–1982 | 18654A1 | Serial Range: 3469428-6225576 |
| MerCruiser | 225/233 | 225-233 | 4-Stroke | 1974–1977 | 18654A1 | Serial Range: 3856268 & Up |
| MerCruiser | 898/228/250/260 | 228-260 | 4-Stroke | 1977–1982 | 18654A1 | Serial Range: 4782330-6225576 |
| MerCruiser | 888 | All | 4-Stroke | 1971–1972 | 18654A1 | Serial Range: 3106717-3472477 |
| MerCruiser | 888 | All | 4-Stroke | 1973–1977 | 18654A1 | Serial Range: 3472478 & Up |
| MerCruiser | 1/1A/1B/1C & EZ | All | 4-Stroke | 1963–1966 | 18654A1 | Serial Range: 1534570-2065186 |
| MerCruiser | 120/140/160/165 | 120-165 | 4-Stroke | 1967–1972 | 18654A1 | Serial Range: 2062141-3443920 |
Technical Specs
- Product Type
- Exhaust Bellows
- Installation
- Connects transom plate to bell housing
- Connection
- Secured with worm gear clamps (included)
- Housing Material
- Rubber
- Housing Color
- Black
- Dimensions
- Approximately 5.25" long (133mm), 2.5" inner diameter (63.5mm) at each end
- Fitting Type
- Compression fit with clamps
- Warranty
- 1 year (typical for aftermarket)
- Other Technical Attributes
- Ribbed construction for flexibility
What’s in the Box
- 1 x Exhaust Bellows (Replaces 18654A1/8M0124227)
- 2 x Worm Gear Clamps (Replaces 54-815504348)
- 2 x Grounding Clips (Replaces 54-86049/8M0126505)
Installation Notes
- Disconnect the boat's battery for safety.
- Trim the sterndrive to the full "up" or "trailer" position.
- Remove the sterndrive assembly following the manufacturer's service manual.
- Carefully loosen the clamps on the old exhaust bellows and remove it from the transom and bell housing.
- Thoroughly clean the mounting surfaces to ensure a clean, debris-free seal.
- Install the new bellows, making sure it is properly seated on both ends.
- Secure the new worm gear clamps and attach the grounding clips.
- Reinstall the sterndrive assembly according to service specifications.
- Once reassembled, lower the drive, reconnect the battery, and check thoroughly for any water leaks.
Troubleshooting & FAQ
What are the signs my exhaust bellows are failing?
Common signs of failure include visible cracks, splits, or rotting of the rubber. The most critical symptom is finding water in your boat's bilge, which could indicate a leak in the bellows or another component.
How can I confirm this part fits my engine?
This bellows kit is designed for a broad range of MerCruiser sterndrives, including the Alpha One (Generations 1 & 2), Bravo (I, II, & III), and other models as listed. The best way to confirm fitment is to match your engine model and serial number range against the compatibility chart provided on this page.
How often should I replace the exhaust bellows?
For preventative maintenance, it is recommended to inspect all bellows annually for signs of wear or damage. A full replacement is advised every 3–5 years, depending on usage (saltwater vs. freshwater) and storage conditions.
Are the clamps and grounding clips included?
Yes, this is a complete kit that includes one exhaust bellows, two heavy-duty worm gear clamps, and two grounding clips required for a standard installation.
Is this an OEM or aftermarket part?
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.
What are the shipping speed and cost?
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
What is the warranty and return policy?
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.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
