Brake Disc Caliper problems of the 2003 GMC Sierra

The problem started when I noticed the rear brakes making excessive noise. Figuring that it was likely worn brake pads, I decided to change them. During the process of changing out the brake pads, I noticed that the rotors had been extremely worn down. This lead to me replacing both rear rotors, only to find that the brakes were not releasing after being applied. I then replaced both rear brake calipers. This did fix the problem of the brakes not releasing. After bleeding the brakes, I took the truck out for a test run. At this point there was a brake line failure and lead to complete brake failure. My concern is due to the fact that the brake lines are very heavily corroded, and I fear that there will be many future problems with the system. The truck has many other rusted parts underneath as well, and I do not use the vehicle for any abnormal driving use that would lead to excessive corrosion.

The rear brake pads squealed & were grinding & the truck had very poor stopping power. The truck was taken to my mechanic & he was doing the brake job; he replaced all four rotors because they were rusted beyond repair. The pads were replaced as well. While he was doing the brakes he observed the brake lines were rusted to a point that it alarmed him & he said they should be changed. He also commented that the brakes had worn very uneven. The front pads were barely worn & were only making contact at a small area of the rotor (about 1/2" of the full face on the rotor). The back pads & rotors were completely worn down & the rotors were ruined. Some of the areas under the truck look as new & other places; mainly the a-frames, brake lines, some frame members, etc. Look like they are 15 years or more older. The brakes were put back together & now they are so tight & won't release the rotors, causing the rotors to over heat. I am now having him replace the back two calipers with replacement calipers that use phenolic pistons rather than steel & are not gm parts.