frozen brake caliper?

[tonycarreon]

so i'm thinking the problem may be a frozen (dying) caliper or piston...

backstory: drove 150 miles in bad rain storms yesterday. drive in the rain from time to time anyway.

for a while now, after it rains the front driver's side brake makes a popping noise when the brake is applied a few times. i always assumed it was just the pad sticking to the rotor.


today, i go to pull out of the parking spot and it makes its usual popping noise, but then when i start to move forward it's a horrible squealing metal on metal noise.

i stop, do a visual look-see and the pads are still good (they have about 6k miles on them at this point). i notice the rotor has a ring of rust on the outside and inside but clear in the middle. the passenger side rotor does not.

i get back in, pump the brakes a few times, put it in reverse and the noise is gone. drive 5 miles back to the house and no noises / popping...

i'm thinking the pad it just sticking to the rotor because of the rust, but it could also be a piston not releasing pressure on the pad...