Front Brakes Are Sticking

[bizzybaldwin]

I have been dealing with an ongoing brake issue with my 2006 GMC Sierra 4WD Z71 5.3L VIN T. I have disc on the front, drums on the rear. I will start from the beginning.

 

I noticed while driving on the Interstate one day that my steering wheel started to shake and I could smell what seemed to be burnt rubber. I pulled over and my rotors were really hot due to my front calipers sticking. I shut the truck off, pumped the brake pedal and they released and I went on my merry way. A couple of days later it did the same thing, but the calipers were only sticking every now and then. I assumed I had bad calipers, so I changed them, and the truck seemed to be back to normal, but only for a couple of days. The issue happened again, this time at night and I could see the rotors glowing orange. I pumped the brakes, they released and I was able to drive home by not touching the brake pedal. Well, the issue has gotten worse and they stick all the time now. I took it to a local service shop and they told me that there was some other fluid in the brake system and anything with a rubberized component needed to be replaced, from the master cylinder, to hoses to caliper and wheel cylinders. I didn't buy this, so I took it to the dealership. They told me that there was some moisture in the system, which caused the fluid to turn GREEN, and I needed a system flush. They said the brakes locking up was a result of bad hoses and the rotors had gotten so hot that it melted the rubber seals on my (new) calipers. So, easy enough, right? Well, I changed the hoses, calipers (again) and flushed the entire system. When I flushed, the fluid that came out of the master cylinder reservoir and the lines was a dark GREEN. I flushed it until it ran clear with new brake fluid at each bleeder port, starting at the furthest from the master cylinder and working around. This did NOT fix the issue with sticking brakes, but it is exactly what the dealership wanted to do, which they quoted for $800. I am simply at a loss for what to do. I was thinking of changing the master cylinder, but I hate to keep dumping money into parts trying to troubleshoot this problem.

 

Does anyone know what could be causing this? What would cause the calipers not to release? One thing to note - when buying the hoses, the auto parts store asked me "Hydraulic or Vacuum system??" They acted like they didn't know what the difference was, but the correct hose was for the Vacuum system.

 

Any help would be greatly appreciated.

[00Silverado4x4]

Dispite putting new calipers on twice, did you check/lube the slides of the calipers. That's the only thing I think of off hand. I don't know the difference between hyraluic or vacuum systems either, however if you do find the problem let us all know as I have the 06 too.

[bizzybaldwin]

Dispite putting new calipers on twice, did you check/lube the slides of the calipers. That's the only thing I think of off hand. I don't know the difference between hyraluic or vacuum systems either, however if you do find the problem let us all know as I have the 06 too.

 

New slide pins were part of the caliper set. I put them on with a good amount of high temp brake grease.

[00Silverado4x4]

Sorry, I've got nothing. Don't know enough about the brake system to make anymore educated guesses.

[govtech]

the last thing to change is the master cyl,might as well ...

 

vacumn pod is big behind the m/cyl and a hose going to engine is vacumn assist

 

hyd assist is for some 3/4 & 1 tons that have diesel engines and several hoses go to power steering pump,

 

you have a 1/2t and therefor vacumn assist brakes

[bizzybaldwin]

Should I also replace the brake booster check valve or the brake booster vacuum hose? Any chance either of those components could cause issues with the brakes sticking?

[sahls01gmc]

I am having the same problem in my 01 2500 (non HD). Has anyone found a solution to this problem? I have 4 wheel disc, and it seems the rear calipers are smoking, and I have just replaced the front calipers.