Before starting work, it is necessary to thoroughly clean and wash the engine, having previously covered all openings with a clean rag to prevent foreign objects from getting inside the engine.
Engine disassembly is discussed in detail in the following subsections. Therefore, the following describes the work that can be performed both on the engine installed in the vehicle and on the engine removed from the vehicle. In the event that a complete disassembly of the engine is required, it will only be necessary to combine individual types of work in the specified sequence.
When disassembling the engine, all moving mating parts should be marked before dismantling them so that in case of their subsequent use, these parts can be installed in their original position. This is especially important when removing pistons, valves, covers and bearing shells. They should be laid out in such a way as to avoid confusion during subsequent assembly.
Never mark bearings and seals with sharp objects ("scribers") or by stamping numbers. Many engine parts are made of aluminum alloy and therefore require very careful handling. If you have to use a hammer to remove certain parts, the hammer should be rubber, plastic or coated with a synthetic material.
[Material taken from a web resource Mercedesman.ru]
Since complete disassembly of the engine is required only in rare cases, and most work can be performed on the engine installed in the vehicle, individual work is described in the relevant sections. In case of major engine repairs, it is necessary to combine individual stages of work from these sections.
The following description applies to all types of engines, since they differ in most cases only in the number of cylinders. The text provides separate references to the design differences of a specific engine.