I put new brake pads on the front of my 06 GMC Z71. After finishing, I noticed I didn't have any brakes. The peddle was spongy so I bled the brakes. And bled the brakes, and bled the brakes. I could never get the pedal to feel like it's supposed to. Took it to a mechanic and he bled the brakes. It still didn't fix the problem. After a major debacle of getting the wrong parts, the mechanic changed the master cylinder. The problem still wasn't fixed because the brake pedal wouldn't push down. So he then had to change the brake booster. When he took it off air "exploded" out of it. My question, is this normal? Why did changing my pads cause me to have $730.00 worth of repairs? I never once had any problems before. I had changed my pads because they had started "squealing." I bought the truck used with 80,000 miles on it, in very good condition. Any help would be greatly appreciated. Thanks!

closed as too broad by Zaid, Fred Wilson, vini_i, DucatiKiller, Pᴀᴜʟsᴛᴇʀ2 Dec 21 '15 at 1:52

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    Is this a Sierra, Yukon, or Yukon XL? Assuming not a Denali as I don't believe they came in Z71 trim. More than likely this is just coincidence. Depending on how the brakes were bled (manually I assume?), it could just be everything just happened. I've got 155k+ on my 06 Silvy Z71 and don't have any issues with the brakes. Also, does this have hydroboost or a normal vacuum booster (assume vacuum, but have to ask)? – Pᴀᴜʟsᴛᴇʀ2 Nov 10 '15 at 23:02
  • When you put the new pads in, did the process involve opening the hydraulic system in any way before you realized you had no brakes? – HandyHowie Nov 11 '15 at 8:58
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    How did you push the pistons back to make space for the new pads? – HandyHowie Nov 11 '15 at 9:01
  • Also realize that if you bleed the brakes by pumping the pedal and you mash it all the way to the floor, it will often push the piston cup further into the master cylinder than it usually goes and collapse the rubber piston cup or get crud stuck under the lip, preventing pressure from building. You should NEVER have pressure in the brake booster vacuum lines. Ever. So if you did, it indicates that either something was done incorrectly or maybe you just heard air rushing in? It should always hold a little bit of vacuum. – Chris Chubb Nov 11 '15 at 20:31

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