Gates 39112 Accessory Drive Belt Tensioner Assembly - Alternator or Power Steering and Water Pump

Overview of Gates DriveAlign Premium OE Automatic Belt Tensioner

The Gates DriveAlign Premium OE Automatic Belt Tensioner (Part Number 39112) is engineered for precise belt tension control in BMW vehicles. Designed specifically for models such as the 328i, 330i, X3, and Z4, this tensioner assembly ensures consistent performance and durability in accessory drive belt systems.

• Thermoplastic construction for durability and heat resistance
• Single smooth backside contact surface pulley without flange
• Compatible with V-ribbed belt types
• One mounting hole for secure installation
• Precise dimensions: 2.76 inch (70 mm) outside diameter, 1.02 inch (26 mm) width
• Bearing bore inside diameter of 0.67 inch (17 mm)
• Includes tensioner assembly and bolt

Detailed Product Description and Specifications

This accessory drive belt tensioner assembly from Gates features a thermoplastic pulley designed to withstand the demanding conditions of engine compartments. The pulley has a smooth backside contact surface and is not flanged, which is suitable for V-ribbed belt applications. The tensioner’s outside diameter measures 2.76 inches (70 mm) with a width of 1.02 inches (26 mm), providing a precise fit for the specified BMW models. The bearing bore inside diameter is 0.67 inches (17 mm), ensuring compatibility with the original equipment specifications.

The part number 39112 corresponds to an OE exact replacement, maintaining factory-level performance and fitment. This tensioner assembly is compatible with a range of BMW vehicles including the 128i, 323i, 325i, 325xi, 328i, 328i xDrive, 328xi, 330i, 330xi, 525i, 525xi, 528i, 528i xDrive, 528xi, 530i, 530xi, X3, X5, and Z4 models.

About the DriveAlign Premium OE Automatic Belt Tensioner Line

The DriveAlign Premium OE Automatic Belt Tensioner line by Gates is designed to meet or exceed original equipment standards. This product line focuses on delivering precise tension control and long service life for accessory drive belt systems. The tensioners in this line are engineered to provide consistent belt alignment and tension, reducing wear on belts and pulleys while supporting optimal engine accessory performance.

Common Applications and Issues Addressed

• Maintains proper tension on V-ribbed accessory drive belts
• Prevents belt slippage and noise in BMW 3 Series and 5 Series models
• Reduces premature belt wear caused by improper tension
• Eliminates vibration and misalignment in accessory drive systems
• Restores factory-level belt tension for BMW X3, X5, and Z4 vehicles

Installation Notes and Tips

• Ensure the mounting surface is clean and free of debris before installation
• Verify the tensioner pulley orientation matches the original equipment setup
• Use the included bolt to secure the tensioner assembly firmly
• Check belt alignment and tension after installation to prevent premature wear
• Consult vehicle service manual for torque specifications and installation procedures

Quality Assurance and Warranty

The Gates DriveAlign Premium OE Automatic Belt Tensioner (Part Number 39112) is manufactured to meet original equipment standards, ensuring reliable performance and durability. This part is rated as an OE exact replacement, providing confidence in fit and function for BMW accessory drive belt systems. Warranty coverage details should be confirmed with the product documentation or supplier.