Mercedes Workshop Manual - Om646 Engine __full__

The OM646 introduced significant advancements in fuel injection. The workshop manual demystifies this complex system:

Uses a high-pressure common rail injection system (CDI) for precise fuel delivery. Mercedes Workshop Manual Om646 Engine

Mounted on top of the valve cover to identify cylinder 1 synchronization. Complete removal instructions for the intake manifold to

Complete removal instructions for the intake manifold to clean out heavy carbon sludge or replace broken swirl flap linkages. Turbocharger Actuator Failure Disclaimer: Always work in a well-ventilated area, use

: The OM646 is famous for surpassing 300,000 miles on original internals. This manual provides the precise torque specs and technical data needed to keep that streak alive.

Disclaimer: Always work in a well-ventilated area, use proper safety stands, and de-pressurize the high-pressure fuel system (consult your manual) before loosening any injector or fuel line.

The most famous OM646 affliction is leaking injectors, often called the "Black Death" or "Dieselkriechen" (diesel creeping). Over time, the copper sealing washers at the base of the injectors can fail. This allows combustion gases and unburnt fuel to escape past the injector, creating a hard, black, tar-like deposit around the injector. Symptoms include a strong diesel smell in the cabin, a knocking or "nailing" sound from the engine bay, and if left unchecked, can lead to seized injectors or damaged cylinder head threads.