Serpentine Belt – Fits MerCruiser Alpha/Bravo V6/V8 (Replaces Mercury/MerCruiser 57-865615-003, 57-865615Q03)
Serpentine Belt – Fits MerCruiser Alpha/Bravo V6/V8 (Replaces Mercury/MerCruiser 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
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
Serpentine Belt – Fits MerCruiser Alpha/Bravo V6/V8 (Replaces Mercu...
Product Details
This high-strength Serpentine Belt – Fits MerCruiser Alpha/Bravo V6/V8 Engines (Replaces 57-865615-003, 57-865615Q03) is designed for a precise fit on Mercury Marine/MerCruiser 4.3L, 5.0L, 5.7L, and 6.2L V6/V8 engines (1999–2016) for Bravo and Alpha models equipped with sea pump cooling systems. It ensures reliable power transmission to all engine accessories.
This belt is a direct interchange for Mercury/MerCruiser part numbers 57-865615-003 and 57-865615Q03, as well as Sierra 18-15100 and Quicksilver 865615Q03.
- Installs on the engine's accessory drive system.
- Constructed from high-strength rubber cords for durability and longevity.
- Backed by a 1-year factory warranty against manufacturing defects.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/MerCruiser | 57-865615-003 |
| Mercury/MerCruiser | 57-865615Q03 |
| Quicksilver | 865615Q03 |
| Sierra | 18-15100 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For MerCruiser applications, compatibility often depends on the specific cooling system (e.g., Alpha with sea pump, Bravo with standard cooling) and serial number range. Please verify your configuration.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | 4.3L | V6 | 4-Stroke | 1999–2016 | 57-865615-003, 57-865615Q03 | Bravo engine or Alpha with sea pump |
| MerCruiser | 5.0L | V8 | 4-Stroke | 1999–2016 | 57-865615-003, 57-865615Q03 | Bravo engine or Alpha with sea pump |
| MerCruiser | 5.7L | V8 | 4-Stroke | 1999–2016 | 57-865615-003, 57-865615Q03 | Bravo engine or Alpha with sea pump |
| MerCruiser | 6.2L | V8 | 4-Stroke | 1999–2016 | 57-865615-003, 57-865615Q03 | Bravo engine or Alpha with sea pump |
| MerCruiser | Alpha | V6/V8 | 4-Stroke | 2001–2016 | 57-865615-003, 57-865615Q03 | With closed cooling |
| MerCruiser | Bravo | V6/V8 | 4-Stroke | 2001–2016 | 57-865615-003, 57-865615Q03 | With standard cooling (s/n 0M320025 and above) |
| MerCruiser | 305 CID | V8 | 4-Stroke | 2001–2016 | 57-865615-003, 57-865615Q03 | Alpha with closed cooling or Bravo with standard cooling |
| MerCruiser | 350 CID | V8 | 4-Stroke | 2001–2016 | 57-865615-003, 57-865615Q03 | Alpha with closed cooling or Bravo with standard cooling |
| MerCruiser | 377 CID | V8 | 4-Stroke | 2001–2016 | 57-865615-003, 57-865615Q03 | Alpha with closed cooling or Bravo with standard cooling |
Technical Specs
- Product Type
- Serpentine Belt
- Installation
- Engine Accessory Drive
- Material
- High Strength Rubber Cords
- Belt Length
- 2,704 mm (106.5 in)
- Belt Type
- Serpentine/Multi-Rib
- Compatibility
- Alpha with Sea Pump, Bravo Standard Cooling
- Color
- Black
- Warranty
- 1-year factory warranty against defects (Mercury/Quicksilver)
- OEM Part Number
- 57-865615-003, 57-865615Q03
What’s in the Box
- 1 x Serpentine Belt (Replaces 57-865615-003, 57-865615Q03)
Installation Notes
- Disconnect the vessel's battery to prevent accidental starting.
- Locate the automatic belt tensioner. Use a socket or breaker bar to rotate the tensioner and release the tension on the belt.
- While the tension is released, carefully slide the old belt off the pulleys. Note the routing path.
- Route the new belt around the pulleys, following the diagram usually found on a decal in the engine bay.
- Ensure the belt's ribs are correctly seated in all pulley grooves.
- Slowly release the tensioner to apply pressure to the new belt.
- Reconnect the battery and start the engine briefly to check for proper belt alignment and function.
Troubleshooting & FAQ
How do I know if this serpentine belt fits my specific engine?
Check the compatibility tables on this page. This belt is for MerCruiser V6/V8 engines (1999–2016) with specific cooling systems, such as Alpha drives with a sea pump or Bravo drives with standard cooling. Always verify your OEM part number (57-865615-003 or 57-865615Q03) for a guaranteed match.
What are common signs of a failing serpentine belt?
Watch for squealing noises from the engine, visible cracks or fraying on the belt, loss of power steering, or engine overheating. Any of these symptoms can indicate that the belt is worn and needs immediate replacement.
How often should I replace my serpentine belt?
As a general guideline, serpentine belts should be inspected annually and replaced every 3-5 years or after 500-700 hours of operation, depending on usage and conditions. Refer to your engine's service manual for specific recommendations.
Is this belt difficult to install?
For those with mechanical experience, replacing a serpentine belt is a straightforward task that typically requires a wrench or breaker bar to release the tensioner. However, due to the importance of correct routing and tension, professional installation is recommended if you are not comfortable performing the job.
What's the difference between an OEM belt and this aftermarket one?
This is an aftermarket part designed to meet or exceed OEM specifications. It is made from comparable high-strength materials and manufactured in a certified facility. It offers the same performance and fit as the original but at a more competitive price point.
Can I use this belt on an engine without a sea pump or with a different cooling setup?
No, this particular belt (2,704 mm length) is specified for MerCruiser V6/V8 engines that use either an Alpha drive with a sea pump or a Bravo drive with standard cooling. Using the wrong length belt will result in improper tension and accessory failure.
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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