Mercedes W463 W251 Oil Seperator Breather Bleeder Valve OM642 A6420102091

Mercedes W463 W251 Oil Seperator Breather Bleeder Valve is an original crankcase ventilation system component designed for OM642 engines used in Mercedes W463 off-road and W251 family models. Thanks to its factory design and precise fitment to the engine's specifications, it ensures stable oil vapor discharge and supports the proper operation of the lubrication system. It is a practical choice for users looking for an OEM component with preserved functionality for professional repair or maintenance.

Specifications and technical data

• SKU: A6420100391
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A6420100391
• Substitutable numbers: A6420100391, A 642 010 03 91, A6420102091, A 642 010 20 91
• Category: Oil Pumps & Parts

Purpose and function in the OM642 engine

The oil separator in the OM642 engine is responsible for the controlled discharge of gases from the crankcase and the separation of oil vapors, which limits their ingress into the intake system. In Mercedes diesel units, this is important for:

• maintaining stable pressure in the crankcase,
• reducing contamination of the intake manifold and auxiliary components,
• limiting engine oil consumption,
• maintaining smooth engine operation across the full load range.

A properly selected oil separator supports the long-term, predictable operation of the OM642 unit, which is particularly important in vehicles operated under higher loads, typical for W463 and W251 models.

Compatibility and interchangeable numbers

The presented oil separator belongs to the Oil pumps and parts group, meaning it was designed to work with the factory Mercedes lubrication system. The element has a dedicated OEM part number and associated interchangeable numbers, which facilitates clear identification in service catalogs and during selection for a specific engine configuration.

Thanks to this, a mechanic or user can verify the compatibility of the part with their vehicle based on catalog data, without the need to use replacements of uncertain origin.

Characteristics of the element and advantages of use

The oil separator for a Mercedes with an OM642 engine is structurally matched to the factory system, which translates into:

• proper flow management of gases and oil vapors,
• preservation of the engine's factory operating parameters,
• reduction of the risk of leaks resulting from ill-fitting replacements,
• easier installation due to compatibility with original equipment.

As a part from the Oil pumps and parts group, the separator works with the lubrication system, affecting oil cleanliness and the operating conditions of moving parts. Proper selection of this component is important during engine service, especially after high mileage or when symptoms of excessive smoke and increased oil consumption appear.

Condition, origin, and service application

The offered oil separator is a used item, sourced from a dismantled Mercedes vehicle. This type of OEM part represents a reasonable compromise between repair cost and maintaining factory technical specifications, which is especially important in the case of specialized engine components.

It works well both for standard replacement during preventive maintenance and for repairs resulting from symptoms typical of a worn ventilation system, such as increased blow-by or intake contamination.

Support with selection and additional technical information

When choosing used lubrication and ventilation system components, it is worth being guided not only by price but primarily by compliance with the OEM part number and interchangeable numbers. This data is available in the product specification and allows you to verify whether the separator will be suitable for the specific version of the OM642 engine in your Mercedes.

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 oil pump housings, covers, or oil return lines, check the available parts in the Mercedes Oil pumps and parts category.

For drivers who want to better understand the differences between remanufactured parts and used originals, our blog guide may be helpful: Remanufactured or used original – which part to choose for repairs?. Meanwhile, in the context of lighting safety and quality, we encourage you to read the article See more and better – a complete guide to selecting and replacing used LED and Xenon headlights, which shows how to consciously choose original components in other key vehicle systems.