Q: My Mercedes 2011 W212 coolant tank water is leaking into the Cylinder number 2

If you are sure that the leak is into an actual cylinder in the cylinder block, then obviously some disassembly will be required to pinpoint the cause and effect the required repairs. If the leak is due to a defective head gasket, it can be resolved fairly readily but if it is not obviously and solely due to a defective head gasket, the block might need to be inspected for cracks. That, of course, requires that the engine be removed. If you would like this problem diagnosed, and then estimated for repair, please request a coolant leak diagnostic. If you request that service, the responding certified mechanic will get this diagnosed and resolved, right at your location. If you have further questions or concerns, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.