The 27mm center bolt does not have to be removed. There are 6 13mm bolts holding the pulley and damper to the hub on the crankshaft. Be sure to mark the pulley and damper to aid in reassembly ( they only fit together one way, one bolt hole is offset from the rest.). Once the pulley is off the water pump r&r is easy. Just be careful to not overtighten the water pump bolts because they are going into the aluminum block.

__________________
Mercedes Benz Master Tech - Retired