BMW 1 3 Series E87 E90 E91 Hex Bolt With Internal Thread Alternator Mount Diesel

BMW E87 E90 E91 Alternator Mounting Bolt is an original mounting component designed for BMW drivetrains with a Diesel engine. It ensures stable, precise mounting of the alternator to the engine block, which translates to reliable accessory operation and correct interaction with the drive belt. Choosing an original mounting bolt is a safe solution for repairs and maintenance of the charging system.

Specifications and technical data

• SKU: 8574809
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 8574809
• Substitutable numbers: 12318574809, 8574809, 12317798455, 7798455, 12317790565, 7790565
• Fuel type: Diesel
• Category: Other Engine Parts

Application and Function in the Drivetrain

The alternator mounting bolt in BMW E87, E90, and E91 models is responsible for the durable connection of the alternator to the engine structure. In Diesel units, vibration and torque loads are higher than in gasoline engines, making the correct selection of the mounting element crucial for:

• maintaining proper accessory belt tension,
• stable alternator operation across the full RPM range,
• reducing play and undesirable vibrations in the accessory area,
• minimizing the risk of damage to alternator brackets and adjacent components.

Using a dedicated mounting bolt allows for maintaining factory thread connection parameters and appropriate clamping force, which is particularly important in used Diesel engines.

Compatibility and Reference Numbers

The presented bolt has been developed as an original BMW part, with an assigned OEM part number and a set of interchangeable numbers, facilitating selection based on manufacturer catalogs and service documentation. This allows it to be safely used as a replacement for earlier versions of alternator mounting bolts in selected Diesel engine configurations.

The presence of reference numbers in the technical specification allows for quick comparison with the existing component in the vehicle and verification of compatibility with the specific alternator and mounting bracket version, without the need for universal, ill-fitting bolts.

Characteristics of an Original BMW Part

As a BMW brand component, the alternator mounting bolt meets the manufacturer's internal standards for mechanical strength, thread quality, and fatigue resistance. In practice, this means:

• appropriately selected material strength class,
• precise thread manufacturing ensuring correct tightening to the torque recommended in the service documentation,
• connection stability under conditions of elevated temperature and vibrations typical for Diesel engines.

The product comes from the Other category, meaning it is a specialized mounting element, strictly related to a specific application in the engine accessory system, not a universal workshop bolt.

Condition, Installation, and Service Application

The bolt is offered as a used part, allowing for economical repair while maintaining the original manufacturer's specifications. In practice, it is suitable for both alternator replacement and for work involving the removal of accessories to access other Diesel engine components.

It is particularly recommended in situations where:

• the original bolt has suffered mechanical damage or corrosion,
• the thread shows signs of wear after multiple tightenings,
• it is necessary to restore the factory alternator mounting configuration after previous incorrect repairs.

Related Components and Further Technical Knowledge

If you are planning a comprehensive repair or upgrade of the engine area in your BMW and need other parts from the same group, such as additional mounting bolts, spacer washers, or accessory brackets, check the available parts in the BMW Other category.

For a better understanding of the structural differences between sports and standard drivetrains, including the impact of engine accessories and mounting elements on unit durability, it is worth reading the article Audi RS vs. Other Models – What Lies Under the Hood and Chassis?, which discusses practical aspects of component selection in high-performance engine versions.

If you want to deepen your knowledge about the benefits of using original mounting elements and accessories in terms of safety and repair cost-effectiveness, the entry OEM Quality Guarantee and Safety – Why Used Original Car Parts Are the Best Choice for Your Car? will also be helpful, describing the importance of OEM components in long-term vehicle operation.