Mercedes W212 W221 Balance Balancing Shaft OM642 Diesel Engine A6420300372

Mercedes W212 W221 Balance Balancing Shaft OM642 Diesel Engine is a precision timing system component designed for the OM642 series diesel engines, used in luxury S-Class models of the W221 generation. This component, belonging to the Camshafts group, is responsible for reducing vibrations and ensuring stable, refined operation of the diesel power unit, which translates into higher driving comfort and reduced stress on other components.

Specifications and technical data

• SKU: A6420300372-1
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A6420300372
• Substitutable numbers: A6420300372, A 642 030 03 72, KZ
• Fuel type: Diesel
• Category: Camshafts

Purpose and function in the OM642 engine

The balance shaft in the OM642 engine plays a key role in compensating for inertia forces generated during the operation of the diesel unit. Thanks to its precisely selected geometry and mass, this component:

• stabilizes the operation of the crankshaft at various engine speeds,
• limits the transmission of vibrations to the engine block and body,
• supports the smooth operation of the crank-piston system in the diesel engine,
• indirectly influences the durability of accessories and acoustic comfort inside the vehicle.

In the case of OM642 units, the use of the correct balance shaft is particularly important due to the high torque and operating characteristics of modern diesel engines.

Technical characteristics and fitment

The presented shaft belongs to the Camshafts category, however, its primary task is the precise balancing of the drivetrain in the OM642 engine. The design was developed specifically for Mercedes vehicles, which ensures proper fitment with the factory lubrication system, oil channels, and timing cover.

The component works with the timing and lubrication system of the diesel engine, therefore, when replacing it, it is recommended to:

• check the condition of the timing chain and shaft drive,
• verify clearances and any signs of wear on the mating gears,
• use the appropriate engine oil in accordance with the manufacturer's specifications.

Benefits of using an original Mercedes component

Using an original balance shaft in the OM642 engine allows for maintaining the factory performance parameters of the power unit. The most important advantages include:

• Structural compatibility – full fitment to the geometry of the engine block and timing system in the Mercedes W221.
• Stable diesel engine operation – reduction of vibrations and oscillations, which promotes smooth unit operation at both low and high RPMs.
• Protection of other components – reduced loads on bearings, mounts, and accessory elements, which can extend their service life.
• Professional service solution – a part intended for workshop applications and repairs in accordance with the manufacturer's procedures.

Component condition and use in service practice

The offered balance shaft is a used part, which makes it an attractive solution for workshops and users looking for an economical alternative that still complies with the original specification. This type of component is particularly useful for:

• overhauling an OM642 unit after a mechanical failure of the timing system,
• comprehensive regeneration of a diesel engine in a Mercedes W221,
• preventive replacement of elements responsible for the smooth operation of the power unit.

By maintaining the factory geometry of the shaft, it is possible to maintain proper system balance, which is significant for both engine durability and the comfort of using a premium class vehicle.

Technical support, selection, and additional materials

When selecting a balance shaft for a specific OM642 engine configuration, it is worth using the manufacturer's markings and vehicle data to ensure full compliance with the factory specification. In case of doubt, comparing it with the removed part and consulting an experienced service center specializing in the Mercedes brand may be helpful.

If you are planning a comprehensive repair or upgrade of the engine area in your Mercedes and need other elements from the same group, such as additional shafts, drive elements, or mating components, check the available parts in the Mercedes Camshafts category.

To compare solutions used in other brands and better understand the importance of correctly selected timing elements in diesel engines, it is worth reading the material describing typical problems with the timing drive in BMW units – they are discussed in detail in the article BMW N47 timing chain – typical failure and repair using original BMW parts.

If you want to deepen your knowledge on the safe selection of used parts, including timing system elements and balance shafts, the guide Safe online purchase of used car parts – a step-by-step guide will be helpful, as it discusses practical principles for selecting components and verifying their origin.