Balmar Serpentine Pulley Kit for Yanmar 3YM30

Description

The Balmar AltMount Serpentine Pulley Conversion Kit is designed specifically for the Yanmar 3YM30 diesel engine. It converts the engine accessory drive to a J10 ten-groove serpentine system, providing greater belt contact and improved load-transfer capability for installations using a higher-output alternator.

High-output alternators demand more mechanical power from the engine than many original charging systems were designed to transmit through a single V-belt. A ten-rib serpentine belt spreads that load across a wider contact area, helping reduce belt slip and improving the drive system’s ability to sustain charging output.

The kit includes three matching J10 pulleys, two 39-inch-circumference serpentine belts, and mounting hardware. The second belt serves as a spare, which is useful for cruising vessels where a replacement may not be readily available. Using a coordinated pulley set also helps maintain correct groove alignment and belt tracking.

Installations using an AT-200A alternator may require a longer belt than the standard 39-inch length included. For Yanmar 3YM30 owners upgrading the alternator and drive system together, this Balmar kit provides the primary components required for a proper J10 serpentine conversion. Explore our full range of alternator mounts & pulleys.