Mercedes X164 W204 W212 W221 350 CDI Cylinder Head Left N/S OM642 A6420103507

Mercedes X164 W204 W212 W221 350 CDI Cylinder Head Left N/S OM642 is a specialized component from the Cylinder Heads category, designed for 350 CDI diesel engines. This used left cylinder head for the OM642 unit is a precision engine component that allows for the professional repair or rebuild of the power unit in popular Mercedes SUV, C, E, and S-Class models. It is an ideal solution for workshops and users expecting compliance with factory design and stable diesel engine performance parameters.

Specifications and technical data

• SKU: A6420100321
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A6420100321
• Substitutable numbers: A6420100321, A 642 010 03 21, A6420103507, A 642 010 35 07
• Location on the vehicle: Left
• Fuel type: Diesel
• Part type: Cylinder Head
• Category: Cylinder Heads

Purpose and technical compatibility

The presented left cylinder head is dedicated to the OM642 350 CDI engine version, used in Mercedes X164, W204, W212, and W221 series vehicles. The cylinder head design is optimized for operation in diesel units, ensuring proper mixture guidance, combustion chamber tightness, and stable cooperation with the diesel injection system. By maintaining the factory geometry of the intake and exhaust ports, as well as the correct configuration for the left side, the cylinder head allows for the preservation of original engine performance parameters, which is crucial for repairs requiring precise component matching.

Construction and function of the cylinder head

The cylinder head in the OM642 engine plays a central role in combustion and gas flow. It is responsible for:

• guiding intake and exhaust ports for each cylinder,
• maintaining combustion chamber tightness in conjunction with the engine block and gasket,
• stable seating of valves, guides, and timing control components,
• dissipating heat from the combustion area to the cooling system. In the case of 350 CDI units, a correctly selected left cylinder head has a direct impact on smooth engine operation, idle quality, and correct compression parameters. Using a component structurally compatible with the OM642 reduces the risk of starting problems, power loss, or uneven operation under load.

Application in the 350 CDI diesel engine

Diesel engines require components resistant to high pressures and temperatures, which is why a properly selected cylinder head is crucial for the durability of the entire unit. In the 350 CDI, the left cylinder head works with the diesel injection system, turbocharger, and exhaust gas recirculation system, creating a coherent air and exhaust flow system. Replacing the cylinder head with an OM642-compatible component allows for the restoration of proper operating conditions in the cylinders, which translates into:

• stable compression pressure in each cylinder,
• more predictable mixture combustion parameters,
• better cooperation with engine control electronics,
• reduction of the risk of further damage within the power unit.

Benefits of using an original Mercedes cylinder head

Using a cylinder head from the same design family as the factory engine provides a number of practical benefits. Factory fitment minimizes the need for modifications, facilitates installation, and allows for the retention of original accessory mounting points. For workshops, this means shorter labor time and a lower risk of issues during the first start-up after repair. A used cylinder head from the Cylinder Heads category is also a reasonable cost compromise while maintaining a design consistent with the requirements of the 350 CDI engine. Combined with a properly prepared mating surface and inspection of mating components (valves, guides, gaskets), it provides a solid base for the professional regeneration of the OM642 unit.

Technical support and additional materials

If you are planning a comprehensive repair or upgrade of the engine area in your Mercedes and need other components from the same group, such as additional cylinder heads, covers, or mounting elements, check the available parts in the Mercedes Cylinder Heads category. For users interested in a broader context of operating power units of this brand, a guide article on maintaining engine accessories in popular C and E-Class models may be useful – you can find it here: Reliability under the star – how to maintain engine accessories in Mercedes-Benz C and E-Class.