Balmar Yanmar 4JH3 3 Pulley Kit Belt - 48 Inch Circumference - 48-B-48
Manufacturer Part #: 48-B-48
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Balmar Yanmar 4JH3 3-Pulley Kit Belt – 48" Circumference – 48-B-48
The Balmar Yanmar 4JH3 3-Pulley Kit Belt (48-B-48) is a marine-grade drive belt specifically engineered for Yanmar 4JH3 diesel engines equipped with Balmar three-pulley alternator conversion kits. Designed to deliver reliable power transfer in high-output charging systems, this belt ensures proper tension, alignment, and long service life in demanding marine environments.
With a 48-inch circumference, this belt is precisely sized to match Balmar’s 3-pulley configurations, helping maintain optimal alternator performance and reducing belt slippage under heavy electrical loads. It is ideal for vessels running high-output alternators, where consistent torque transfer is critical for efficient battery charging and overall system reliability.
Constructed from durable, heat- and wear-resistant materials, the Balmar 48-B-48 belt is built to withstand continuous-duty operation, vibration, and exposure to marine conditions. Whether replacing a worn belt or completing a new alternator installation, this belt provides a dependable fit and performance you can trust.
Key Features
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High-Torque Performance: Specifically designed to transfer the massive mechanical load of 100A to 170A alternators without stretching or slipping.
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K6 Serpentine Profile: 6-groove design maximizes surface area contact with the crank, water pump, and alternator pulleys.
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Precision Fit: 48-inch (1219mm) circumference, optimized for the geometry of the Yanmar 4JH3 engine block when equipped with Balmar pulleys.
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Synthetic EPDM Construction: Resistant to heat, oil, and engine room contaminants, ensuring a longer service life than standard automotive belts.
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Reduced Noise: The serpentine design runs significantly quieter than traditional single or dual V-belt setups.
Technical Specifications
| Feature | Details |
| Model Number | 48-B-48 |
| Engine Compatibility | Yanmar 4JH3 Series (with AltMount Kit) |
| Belt Profile | K6 Serpentine (6-Groove) |
| Circumference | 48 Inches (1219 mm) |
| Material | Heavy-Duty EPDM |
| Application | Marine Diesel High-Output Charging |
What’s In The Box?
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1 x Balmar 48-B-48 Serpentine Belt: A premium, heavy-duty 6-groove (K6) EPDM belt with a 48-inch circumference.
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Product Sleeve/Label: Includes the Balmar part number and barcoding for easy identification and inventory management.
Critical Spare Parts Advice
When purchasing the 48-B-48, many experienced cruisers follow the "One to Use, One to Spare" rule. Because these belts are part of a proprietary AltMount conversion system, they are rarely found at local automotive or general hardware stores.
It is highly recommended to keep a secondary 48-B-48 in your onboard spares kit to prevent being stranded without a charging system or water pump operation.
Related Components (Sold Separately)
If you are performing a full maintenance cycle on your Yanmar 4JH3, you may also need:
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Balmar AltMount Pulley Kit: If you do not already have the serpentine conversion hardware.
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Belt Tensioner Tool: To ensure the 48-inch belt is seated with the correct deflection.
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Replacement Pulley Shims: Useful if you need to re-align the alternator after a belt change to prevent "dusting."
Pro Tip: Always keep a spare 48-B-48 belt on board. High-output alternators put significantly more stress on belts than factory units; having a backup ensures you aren't left without charging power in remote locations.
BRAND: Balmar
Manufacturer Part Number: 48-B-48
Balmar Yanmar 4JH3 3 Pulley Kit Belt - 48 Inch Circumference - 48-B-48 is backordered and will ship as soon as it is back in stock.
Balmar Yanmar 4JH3 3 Pulley Kit Belt - 48 Inch Circumference - 48-B-48
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