brake pad replacement W126 91 350SDL

I can't compress the calipers to get the new pads in. I tried large hose pliers to grip the old pad back and the housing and slowly squeeze. I also used a screwdriver to pry the old pad back.
Neither attempt works.
Is there a trick?

I pry mine back with a screwdriver - same on 81 300D and 91 350SDL.

I know you've of course loosened the Bleeder valve on these calipers correct? You seem to be going about it the right way, so just a thought.

Never had to loosen bleeder valve on any of mine to push the pad back.

Have always loosened mine to make it easier and it's always worked out for the best.

No, don't loosen the bleed screw.

Did you remove both pads, then try to push back the piston? If so, this will some times cause the piston opposite to the one you are compressing to push out past the seal which will lock it in place.

The correct procedure is to pull out one pad, push it's piston back with a screwdriver, put in the new pad, then repeat the procedure for the other pad. In other words replace one pad at a time.

It sounds like you have caused a piston to push out past it's seal. When this happens, it's as if the piston is welded in place.

The cure is to either rebuild the caliper or replace it.

If you are replacing the pads one at a time and you still have this problem, I expect that it is caliper rebuild time.

Good luck,

Larry, that's the proc. I use - one pad at a time.