I've been having an issue with my front passenger side caliper for the past year. I first noticed a light scraping noise that slowed and sped up with vehicle speed. I replaced all 4 calipers last year and have flushed brake fluid twice now. The scraping is louder now but seems to come and go as I'm driving. I verified the sound is the brake pad lightly rubbing against the rotor. The caliper piston is not fully retracting. I don't know where to turn now. Could this be a proprtioning valve issue? A buddy of mine said he had same issue on a different car and he fixed it by replacing rubber brake hose at the caliper. Any ideas?

 

you could have a leak in the system or a bad master cylinder are you loosing brake fluid at all?

 

Remove caliper and try and push in the piston. Should go in easily. If it does, no problem
with the caliper, but if there is resistance, undo bleeder and try again. If it now goes in easier,
replace brake line, if still resistance replace caliper.
Purchase an inexpensive infrared digital thermometer and monitor rotor temps.

 

Did you try looking at the slides and cleaning them up and adding some brake lube to them and making sure they're moving smoothly? I had an issue with the calipers doing the same and that fixed it.

 

this is your answer. Probably your caliper

 

I did remove the caliper and checked the slides and piston. I re-greased the slides and they seem to be fine. I pushed the piston back in and it went in just fine. With the caliper off of the rotor, I had someone press the brake and watched the piston. It comes out but does not retract back into the caliper when the brake is released.

 

It's not supposed to visually retract. It just floats and stops applying pressure