Serpentine Belt – Fits MerCruiser V6/V8 (Replaces 57-865615-003, 57-865615Q03)
Serpentine Belt – Fits MerCruiser V6/V8 (Replaces 57-865615-003, 57-865615Q03) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Serpentine Belt – Fits MerCruiser V6/V8 (Replaces 57-865615-003, 57...
Product Details
This replacement Serpentine Belt is designed for MerCruiser 4.3L, 5.0L, 5.7L, and 6.2L V6/V8 engines from 1999–2016. It fits Alpha sterndrives equipped with closed cooling and Bravo sterndrives with standard cooling, ensuring reliable power transmission to engine accessories.
It serves as a direct replacement for Mercury/MerCruiser part numbers 57-8638763, 57-865615-003, and 57-865615Q03, as well as aftermarket equivalents from Sierra, GHmarine, UanofCn, and Heurofosh.
- Installs on the engine's accessory drive to power the water pump, alternator, and other components.
- Designed for gasoline-fueled marine engines.
- Engineered as a direct OEM-equivalent fit for straightforward installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Superseded By |
|---|---|---|
| Mercury/MerCruiser | 57-8638763 | 57-865615-003 |
| Mercury/MerCruiser | 57-865615-003 | 57-865615Q03 |
| Mercury/MerCruiser | 57-865615Q03 | |
| Sierra | 18-15100 | |
| GHmarine | 578638763 | |
| UanofCn | 578656150003 | |
| Heurofosh | 578638763 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For MerCruiser models, pay close attention to the serial number (s/n) ranges to ensure correct fitment, as different parts may be used on the same model in different production years.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | 4.3L Alpha | 4-Stroke | 2000–2004 | 57-865615-003 | s/n from OL619000 | |
| MerCruiser | 4.3L Bravo | 4-Stroke | 2000–2004 | 57-865615-003 | s/n from OL619000 | |
| MerCruiser | 4.3L MPI Alpha/Bravo | 4-Stroke | 2000–2004 | 57-865615-003 | s/n from OL619000 | |
| MerCruiser | 5.0L Alpha | 4-Stroke | 2001–2004 | 57-865615-003 | s/n from OL619000 | |
| MerCruiser | 5.0L Bravo | 4-Stroke | 2000–2004 | 57-865615-003 | s/n from OL619000 | |
| MerCruiser | 5.0L MPI Alpha/Bravo | 4-Stroke | 2000–2004 | 57-865615-003 | s/n from OL619000 | |
| MerCruiser | 5.7L Alpha | 4-Stroke | 2000–2004 | 57-865615-003 | s/n from OL619000 | |
| MerCruiser | 5.7L Bravo | 4-Stroke | 2000–2004 | 57-865615-003 | s/n from OL619000 | |
| MerCruiser | 350 MAG Alpha | 4-Stroke | 2000–2004 | 57-865615-003 | s/n from OL619000 | |
| MerCruiser | 350 MAG Bravo | 4-Stroke | 2000–2004 | 57-865615-003 | s/n from OL619000 | |
| MerCruiser | 350 MAG MPI Alpha/Bravo | - | 4-Stroke | 2000–2016 | 57-865615-003 | For engines with s/n 0M320025 through 2A455872 |
| MerCruiser | 377 MAG | - | 4-Stroke | 2001–2016 | 57-865615-003 | For engines with s/n 0M320025 through 2A455872 |
| MerCruiser | MX 6.2L MPI Bravo | - | 4-Stroke | 2000–2009 | 57-865615-003 | s/n 0M300000 through 0W309999 |
| MerCruiser | MX 6.2L MPI Horizon Bravo | - | 4-Stroke | 2000–2009 | 57-865615-003 | s/n 0M300000 through 0W309999 |
Technical Specs
- Product Type
- Serpentine Belt
- Installation
- Engine Accessory Drive
- Fuel Type
- Gasoline
- Housing Color
- Black
- Dimensions
- 2,704 mm length (approx. 106.5 in / 52")
- Fitting Type
- Direct OEM Replacement
- Warranty
- 1 year manufacturer warranty (Mercury/Quicksilver)
- Other Technical Attributes
- Designed for driving multiple accessories including water pump, alternator and other engine components
What’s in the Box
- 1 x Serpentine Belt (57-865615-003/57-865615Q03)
Installation Notes
- Disconnect the battery and ensure the engine is cool.
- Locate the belt tensioner and use a suitable tool (e.g., breaker bar or socket wrench) to release the tension on the old belt.
- While holding the tensioner, carefully slip the old belt off the pulleys.
- Memorize or photograph the belt's routing path before removal.
- Inspect all pulleys for damage, wobble, or seizure. Clean them of any dirt or grease.
- Route the new belt around the pulleys according to the engine's diagram, saving the easiest pulley (usually the water pump or an idler) for last.
- Release the tensioner to apply pressure to the new belt.
- Double-check that the belt is correctly seated in the grooves of every pulley.
- Reconnect the battery, start the engine, and briefly observe the belt to ensure it tracks smoothly.
Troubleshooting & FAQ
How do I find my MerCruiser engine serial number?
The serial number is typically found on a metal plate or sticker on the engine block, flame arrestor cover, or another prominent location. Use this number to cross-reference with our compatibility table.
What are the signs of a failing serpentine belt?
Common signs include high-pitched squealing or chirping noises from the engine bay, visible cracks or fraying on the belt, loss of power to accessories like the power steering or alternator (indicated by warning lights), or engine overheating if the water pump is driven by the belt.
What is the recommended replacement interval for this belt?
While there's no fixed interval, it's good practice to inspect the belt at least annually or every 100 hours of operation. Many service manuals recommend replacement every 3-5 years or 300-500 hours, whichever comes first, to prevent unexpected failure.
Can I replace this belt myself?
Yes, replacing a serpentine belt is a common maintenance task for those with basic mechanical skills and the correct tools to release the belt tensioner. However, if you are unsure about the routing or tensioning procedure, professional installation is recommended.
Why is my new belt making noise?
Noise from a new belt is often caused by incorrect tension, misalignment of pulleys, or contamination (like oil or coolant) on the belt or pulleys. It can also indicate wear on another component, such as a tensioner or pulley bearing, which the new belt is making more apparent.
Does this belt come with a tensioner?
No, this listing is for the serpentine belt only. The belt tensioner and idler pulleys are separate components and should be inspected for wear during belt replacement.
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.
Payment & Security
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