V-Belt – Fits Volvo Penta AQ271, AQ311 & 5.7L V8 350 Engines (978750, 966857)
V-Belt – Fits Volvo Penta AQ271, AQ311 & 5.7L V8 350 Engines (978750, 966857) 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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V-Belt – Fits Volvo Penta AQ271, AQ311 & 5.7L V8 350 Engines (9...
V-Belt – Fits Volvo Penta AQ271, AQ311 & 5.7L V8 350 Engines (978750, 966857) is backordered and will ship as soon as it is back in stock.
Product Details
This high-quality V-Belt – Fits Volvo Penta AQ271, AQ311 & 5.7L V8 350 Engines (978750, 966857) is engineered for reliable power transmission on various Volvo Penta marine engines. It is designed for 4-stroke models, including the AQ271 and AQ311 series, and a wide range of 5.7L V8 350 engines from the 1970s through the 1990s.
This belt is a direct replacement for Volvo Penta part numbers 978750, 966857, 22298172, and 20405712, as well as Sierra Marine 18-4046.
- Installs on the engine's accessory drive to power the 50 amp alternator.
- Constructed from heat, grease, and dust-resistant rubber with high-strength synthetic cords.
- Engineered for static conductivity and reduced noise and vibration.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket brands.
| Brand | Part Number |
|---|---|
| Volvo Penta | 978750 |
| Volvo Penta | 966857 |
| Volvo Penta | 22298172 |
| Volvo Penta | 20405712 |
| Sierra Marine | 18-4046 |
Engine & Model Compatibility
Confirm your engine model in the table below.
This V-belt is compatible with a wide array of Volvo Penta engines. Please check your specific model and OEM part number to ensure a correct fit.
| Brand | Model | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|
| Volvo Penta | AQ271A | 4-Stroke | 978750 | |
| Volvo Penta | AQ271B | 4-Stroke | 978750 | |
| Volvo Penta | AQ271C | 4-Stroke | 978750 | |
| Volvo Penta | AQ271D | 4-Stroke | 978750 | |
| Volvo Penta | AQ311A | 4-Stroke | 978750 | |
| Volvo Penta | AQ311B | 4-Stroke | 978750 | |
| Volvo Penta | AQ175A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ200B | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ225B | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ200C | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ200D | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ225C | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ200F | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ205A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ205LB | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ211A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ225D | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ225E | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ225F | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ231A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ231B | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ231LB | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ260A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ260B | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | BB260A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | AQ290A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | BB231A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | BB261A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | 430 | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | 430A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | 430B | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | 500 | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | 500A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | 501A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | 571A | 4-Stroke | 978750 | 5.7L V8 350 model |
| Volvo Penta | BB225B | 4-Stroke | 978750 | |
| Volvo Penta | BB225C | 4-Stroke | 978750 | |
| Volvo Penta | BB260B | 4-Stroke | 978750 | |
| Volvo Penta | BB260C | 4-Stroke | 978750 | |
| Volvo Penta | 501B | 4-Stroke | 966857 | Also listed with 978750 |
| Volvo Penta | 570A | 4-Stroke | 966857 | Also listed with 978750 |
| Volvo Penta | 572A | 4-Stroke | 966857 | Also listed with 978750 |
| Volvo Penta | MS4A | 4-Stroke | 966857 | Also listed with 978750 |
Technical Specs
- Product Type
- Alternator V-Belt
- Installation
- Engine accessory drive
- Length
- 1200 mm (47.24")
- Application
- 50 amp alternator
- Material
- Heat and grease resistant rubber with synthetic cords
- Color
- Black
- Belt Section
- AW-15
- Top Width
- 11.18 mm (0.44")
- Belt Depth
- 7.94 mm (0.3125")
- Outside Circumference
- 1411.48 mm (55.57")
- Properties
- Static conductive, resistant to heat, grease, dust and cracking
- Other Technical Attributes
- High-flexibility cushion area, reduced noise and vibration
What’s in the Box
- 1 x V-Belt (978750/966857)
Installation Notes
- Disconnect the boat's battery to prevent accidental starts. Ensure the engine is cool to the touch.
- Locate the alternator and identify the V-belt path and tensioner pulley.
- Loosen the alternator mounting bolts or the tensioner pulley to release tension on the old belt.
- Carefully slip the old belt off the pulleys. Note its routing path.
- Compare the new belt with the old one to ensure the length and width match.
- Route the new belt onto the pulleys, following the correct path. Start with the largest pulley and end with the alternator or tensioner.
- Apply tension to the belt by tightening the alternator or tensioner. Tension is correct when the belt deflects about 1/2 inch under firm thumb pressure at its longest span.
- Tighten all mounting bolts to secure the alternator/tensioner.
- Reconnect the battery. Start the engine briefly to check for proper belt tracking and listen for any unusual noises.
Troubleshooting & FAQ
How do I know if my V-belt needs replacing?
Inspect the belt for signs of wear such as cracking, glazing (shiny surface), fraying, or missing chunks. Squealing noises on startup or during operation, especially when under load, are also a strong indicator that the belt is worn or loose and needs attention.
Will this fit my engine if it's not on the compatibility list?
We can only guarantee fitment for the models listed. If your model is not on the list, do not purchase. Please cross-reference using the OEM part numbers (978750, 966857) to ensure this belt matches your engine's requirements.
What is the difference between part numbers 978750 and 966857?
Part number 978750 is the primary reference for many applications, while 966857 is also listed for several models, indicating they are generally interchangeable. This replacement belt covers both numbers. Always verify the required part number for your specific engine serial number.
What causes a new V-belt to fail prematurely?
Premature failure is often caused by incorrect tensioning (too loose or too tight), misaligned pulleys, or contamination from oil or grease. Ensure all pulleys are clean and spin freely before installation.
Is this belt difficult to install?
Installation is straightforward for those with mechanical experience. It involves loosening the alternator to release tension, swapping the belt, and re-tensioning. However, due to the importance of correct tensioning and pulley alignment, professional installation is recommended if you are unsure.
Why is the belt squealing after installation?
Post-installation squealing usually indicates incorrect tension. If it's too loose, it will slip and squeal. If it's too tight, it can cause excessive noise and strain on the bearings of the alternator and water pump. Re-check the tension after a short run-in period.
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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