78458A1 Exhaust Tube Bellow – Fits MerCruiser R MR Alpha One Bravo I II III Blackhawk
78458A1 Exhaust Tube Bellow – Fits MerCruiser R MR Alpha One Bravo I II III Blackhawk is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
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78458A1 Exhaust Tube Bellow – Fits MerCruiser R MR Alpha One Bravo ...
78458A1 Exhaust Tube Bellow – Fits MerCruiser R MR Alpha One Bravo I II III Blackhawk is backordered and will ship as soon as it is back in stock.
Product Details
The 78458A1 Exhaust Tube Bellow is designed for MerCruiser R/MR/Alpha One (serial no. 6225577 & up, 1983–1990), Bravo I, II, III (serial no. OB664190 & up, 1988 and later), and Blackhawk (serial no. 0F18677 & up, 1994–1995) sterndrive applications. This exhaust bellow connects the exhaust system components while allowing flexibility during engine movement.
This part directly replaces MerCruiser 78458A1, Sierra 18-2760, Mallory 9-72810, and GLM 89150.
- Includes stainless steel clamp for secure installation
- Engineered to meet or exceed OEM specifications
- Suitable for freshwater and saltwater environments
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| MerCruiser | 78458A1 |
| Sierra | 18-2760 |
| Mallory | 9-72810 |
| GLM | 89150 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Serial Number | Years |
|---|---|---|---|
| MerCruiser | R/MR/Alpha One | 6225577 & UP | 1983–1990 |
| MerCruiser | Bravo I, II, III | OB664190 & UP | 1988 and later |
| MerCruiser | Blackhawk | 0F18677 & UP | 1994–1995 |
Technical Specs
- Part Type
- Exhaust Tube Bellow
- OEM Reference
- 78458A1
- Material
- Rubber with reinforced construction
- Clamp Included
- Stainless steel
- Application
- MerCruiser Sterndrive Exhaust System
What's in the Box
- 1 × Exhaust Tube Bellow (78458A1)
- 1 × Stainless Steel Clamp
Installation Notes
- Disconnect battery and ensure engine is cool before starting work.
- Remove outdated or damaged exhaust bellow by loosening the existing clamps.
- Inspect mating surfaces on exhaust components for corrosion, cracks, or debris. Clean thoroughly.
- Slide new exhaust bellow onto the exhaust tube, ensuring proper alignment with both connection points.
- Position the stainless steel clamp over the bellow ends and tighten securely without over-torquing.
- Check for full seating and confirm no gaps or misalignment exist.
- Reconnect battery and run engine briefly to verify proper exhaust flow and seal integrity.
- Inspect for leaks or unusual exhaust noise; re-tighten clamps if necessary.
Troubleshooting & FAQ
How do I know if my exhaust bellow needs replacement?
Look for visible cracks, tears, or brittleness in the rubber material. Exhaust leaks, unusual exhaust odor in the bilge, or water intrusion near the exhaust area are common signs of failure.
Will this fit my MerCruiser Alpha One Gen II?
Yes, this exhaust bellow is compatible with MerCruiser Alpha One Gen II drives with serial numbers 6225577 and up (1983–1990). Always verify your serial number before ordering.
Can I reuse the old clamp?
It is not recommended. This kit includes a new stainless steel clamp designed to provide proper tension and corrosion resistance. Reusing old clamps may compromise seal integrity.
What tools are required for installation?
You will typically need a socket set or wrenches to loosen and tighten hose clamps, a flathead or nut driver for clamp adjustment, and basic hand tools for accessing the exhaust assembly.
Is this bellow suitable for saltwater use?
Yes, the exhaust bellow is constructed from durable rubber and includes a stainless steel clamp, making it suitable for both freshwater and saltwater marine environments.
How often should the exhaust bellow be inspected?
Inspect the bellow at least once per season or every 100 hours of operation. Replace immediately if cracks, splits, or softening are detected to avoid exhaust leaks and water damage.
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 against 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
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