Serpentine Belt – Fits MerCruiser Alpha/Bravo V6/V8 Engines (Replaces 57-865615Q03, 57-865615-003)
Serpentine Belt – Fits MerCruiser Alpha/Bravo V6/V8 Engines (Replaces 57-865615Q03, 57-865615-003) 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.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Serpentine Belt – Fits MerCruiser Alpha/Bravo V6/V8 Engines (Replac...
Serpentine Belt – Fits MerCruiser Alpha/Bravo V6/V8 Engines (Replaces 57-865615Q03, 57-865615-003) is backordered and will ship as soon as it is back in stock.
Product Details
This Serpentine Belt – Fits MerCruiser Alpha/Bravo V6/V8 Engines (Replaces 57-865615Q03, 57-865615-003) is engineered for Mercury MerCruiser V6/V8 (305, 350, 377 cid) engines from 2001–2016 (serial numbers 0M320025 through 2A455872). It fits Alpha configurations with closed cooling and Bravo configurations with standard cooling, ensuring reliable power transmission for engine accessories.
It is a direct replacement for MerCruiser part numbers 57-865615-003, 57-865615Q03, 57-8638763, 57-862807, 57-862087A1, and Sierra 18-15100.
- Installs as a direct replacement for your original belt.
- Constructed from durable engineered elastomer with reinforcement fibers.
- Designed for specific MerCruiser V6 and V8 engine cooling system configurations.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| MerCruiser | 57-865615-003 |
| MerCruiser | 57-865615Q03 |
| MerCruiser | 57-8638763 |
| MerCruiser | 57-862807 |
| MerCruiser | 57-862087A1 |
| Sierra | 18-15100 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Engine Size | Configuration | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | Alpha | 4.3L V6, 5.0L V8, 5.7L V8, 377 cid V8 | With closed cooling system | 2001–2016 | 57-865615-003, 57-865615Q03 | Serial numbers 0M320025 and above |
| MerCruiser | Bravo | 4.3L V6, 5.0L V8, 5.7L V8, 377 cid V8 | With standard cooling system | 2001–2016 | 57-865615-003, 57-865615Q03 | Serial numbers 0M320025 through 2A455872 |
Technical Specs
- Product Type
- Serpentine Belt
- Length
- 2,704 mm (106.5 in)
- Installation
- Direct replacement
- Material
- Engineered elastomer with reinforcement fibers
- Compatibility
- MerCruiser V6/V8 engines with specific cooling configurations
- UPC
- 745061630437
- Warranty
- 1 Year
What’s in the Box
- 1 x Serpentine Belt (57-865615Q03)
Installation Notes
- Disconnect the boat's battery before starting work.
- Locate the serpentine belt and note its routing path around the pulleys. If needed, draw a diagram.
- Use a long-handled breaker bar or a dedicated belt tensioner tool to rotate the automatic tensioner and release pressure on the belt.
- While holding the tensioner, carefully slide the old belt off the pulleys.
- With the belt removed, inspect all pulleys for wobble, signs of wear, or damage. Spin them to ensure they rotate smoothly.
- Route the new belt according to your diagram, starting with the crankshaft pulley and leaving a smooth pulley (like the water pump) for last.
- Once the belt is routed correctly on all grooved pulleys, release the tensioner to apply pressure.
- visually inspect the belt to ensure it is seated correctly in every pulley groove.
- Reconnect the battery and start the engine briefly to check for proper operation.
Troubleshooting & FAQ
How do I know if this belt fits my engine?
Your engine must match the criteria in the "Engine & Model Compatibility" section. This belt is for MerCruiser V6/V8 engines (2001-2016): Alpha models with closed cooling (SN 0M320025+) and Bravo models with standard cooling (SN 0M320025 to 2A455872). Always verify your specific model and serial number.
What are the signs of a failing serpentine belt?
Common symptoms include a loud squealing noise from the engine bay, visible cracks or fraying on the belt's surface, chirping sounds that change with engine RPM, or dashboard warning lights for the battery or coolant temperature.
What is the recommended replacement interval?
For marine environments, it is best practice to inspect the belt at the beginning of each season and at regular service intervals. As a general guideline, consider replacement every 3-5 years, or immediately if you notice any signs of glazing, cracking, or other wear.
How is an aftermarket part different from OEM?
This listing is an aftermarket replacement, not an OEM component. It is manufactured in an ISO 9002 facility to meet or exceed original equipment specifications for fit, form, and function, offering a high-quality alternative at a better value.
What are your shipping and warranty policies?
We provide fast worldwide shipping, with most orders arriving in 5–15 days. Standard shipping is free, with expedited options available at checkout. The belt is covered by a 1-year warranty against manufacturing defects. If you have an issue, please contact our support team with your order details.
What if I order the wrong part?
We accept returns of unused items in their original condition within our standard return window. Please see our full policy page or contact us for instructions. We strongly recommend verifying compatibility before purchasing to avoid errors.
Safety & Important Info
- Verify images and specifications against your original part before purchase. If anything differs, even if your model is listed as compatible, do not order.
- This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
- Professional installation is highly recommended to ensure proper fit, function, and safety.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
- Fast Global Fulfillment — With free standard delivery to most regions, you can expect your parts in 5–15 days.
- Manufacturer-Direct Value — By working directly with manufacturers, we offer fair pricing without compromising on materials or quality control.
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