Date registered: Nov 2008
Vehicle: 1981 300TD 310k--1966 230 165k--1970 280se 172k
Location: Ohio City, Ohio
Mentioned: 1 Post(s)
Quoted: 33 Post(s)
I found that what causes the pistons to stick is moisture getting past the rubber boot and rusting/pitting both the piston and the bore toward the "outside" of the O ring.
If there is anything more than minor staining on these components, it really isn't worth rebuilding. For stains, I've tried polishing the chrome surface on the pistons using jeweler's rouge and fine steel wool on the bore with varying results.
A stuck piston is truly a PIA to remove. Once the air pressure technique no longer works, I've had to soak with PBblaster and worked the piston every so little at a time using a screwdriver to wedge in the piston boot groove, then compress the piston, rinse and repeat. If they are this hard to get out, you are not likely to save the caliper.
If you do rebuild, make sure you return the pistons back to their original bores.
I still rebuild calipers, but I always wonder why I don't just replace them when it's all said and done.
1981 300TD--310k miles
1970 280sel--172k miles
1966 230--162k miles
Last edited by carpenterman; 11-25-2012 at 08:54 AM.