I am changing the rotors and pads on my 06 c230. I have the rotor off and the pads removed. The inner piston was easily compressed with a c clamp, however, I cannot compress the outer piston. What am i doing wrong? Is there something I am missing? I tried loosening and removing the bleeder screw and also removing the cap from the master cylinder. Nothing seems to work. I tried a search and everyone says it should just compress, I have got to be missing something. Thanks in advance for your help.

 

press the brake pedal and see if it moves but dont do this with the caliper off. or youll blow out the piston and then your F'd. its possible that the piston came out to far and it needs to be worked back into its proper place. leave the old brake pad in and then push in the piston so your pushing in more evenly.