I have a 2006 z71 Crew cab with 5.3L and just over 200,000 miles on it. Pads on the front and drums on the back. Both front calipers were sticking. When I jacked the truck up I could barely turn the front wheels by hand. When I opened the bleeder on caliper then the caliper would release and I could turn the wheel. Both front calipers were doing this. Sliders were not sticking then moved freely. The outside pad (both drive and passenger sides) was worn out and the inside pad had plenty left. I replaced the rubber brake hose that attaches to caliper on driver and passenger side, replaced rotors and pads re-greased sliders. I sucked old brake fluid out of master cylinder (it was dark black) and filled it with new brake fluid and bleed the brakes at all 4 wheels until I had clean brake fluid coming out of bleeder at all 4 wheels. Gave it a short test drive came back front rims were very hot to touch. I jacked truck up and calipers are sticking again. I then replaced both front calipers, replaced sliders and the rubber boots and cleaned the holes very good and bleed front brakes and test drive. Now when I jack truck up and turn the wheels by hand there is some drag on them and they rims still get very hot to touch after a shot drive like 6 miles round trip at about 40 mph. My wife has a 2006 Tahoe with disc brakes, as a comparison I drive it and then touch the rims they are cool to touch. I jacked it up and can turn wheel by hand easy with no drag. The sliders are moving fine, the pads are not stuck or binding. I think the master cylinder is my next part to replace. I just wanted some more opinions to see if I'm overlooking something. The rear rims are not hot to touch after driving. Like I said it has drums on the rear. I have not checked them, you can tell when driving slow that the truck has some drag on it when you let off the gas pedal.

 

At this point, I would replace the calipers themselves... it sounds like there might be some pretty gunky brake fluid in there... and they're ten years old with 200k miles.


I could be wrong, but I did the calipers on my 98 and it fixed all my problems... not all that expensive either

 

Thanks for the reply. I have already replaced both calipers and flushed all the old brake fluid out of system before I installed the new calipers. I still have the problem that both calipers are not releasing all the way. I going to buy a new master cylinder today and replace it and bleed the brakes. I will give an update of that fixes it or not.

 

A couple things that stick out here. One, is this a 2500 and/or does it have a hydro boost brake booster system? I've found before that on a 2500 suburban the valves inside the hydro boost would leave the brakes applied when driving, causing binding in turns and super hot brakes and wheels.

Second, how is your brake pedal free play? This page describes it pretty nicely how to check it, but to adjust your brake pedal free play you'd have to remove the brake booster and adjust the rod that way. If you have some slop to it, then I wouldn't mess with it. Just asking, and it's simple to check!

Third, pull your ABS fuse and try driving around again. If your ABS is activating while you're driving from a bad wheel speed sensor, that could be causing your brakes to get hot as well.

So after you did the calipers and hoses, and the brakes got hot again, what happened when you crack the bleeder screw? Fluid squirt out or no.

 

Thanks for the reply Nullhead. My truck is a 1500 no hydro boost. After calipers and hoses after driving, when I opened bleeder on caliper fluid did squirt out when I bleed the brakes. I replaced my master cylinder. When I removed the old one I found the the brake booster was full of brake fluid just below the hole where the master cylinder goes in. I also found on the old master cylinder where the plunger goes in there was a lot of sludge. The old brake fluid looked pretty bad when I flushed the system, the brake booster was full of old nasty brake fluid. I removed all the brake fluid from the booster with a vacuum pump. I did the bench bleed on the new master cylinder installed it and bleed brakes at master cylinder and front calipers. I have driven the truck a few times now and it feels like the front brakes are still dragging, the front rims are getting very hot and it has a smell like the brakes are hot/burning. My brake pedal feels like it only presses down about 1 inch when I start feeling pressure and the brakes applying. Before replacing the master cylinder this was kinda of intermittent the pedal feel. I will pull the ABS fuse and give it a test drive to see if that makes a difference. I have a code scanner and there are no codes coming up. Could a bad brake booster be causing my brakes to stick and the pedal feel like it does? I will test drive tomorrow with ABS fuse out and post an update. So far I have replaced brake master cylinder, both front calipers, both front rubber brake hoses, rotors, pads and flushed old brake fluid out, bleed all 4 wheels until new clean brake fluid was coming out at each wheel.

 

Sorry looks like the link in my post got removed, or I never got it included into my post.

Yes, a brake booster can certainly cause the brakes to be partially applied when you're driving. Usually in the shop, if a customer's car were to come in with brake fluid inside the brake booster, and the master cylinder leaking, the vehicle would get both components replaced.

Your brake booster works off of a delicate balance of atmospheric pressure and a carefully balanced diaphragm and spring assembly. If that diaphragm is damaged by brake fluid, or is sticking, it can cause the brake booster push rod to stay depressed into the master cylinder.

I'd put a booster on it and see what happens.

 

Thanks again Nullhead for your help. With my work schedule I have not had a chance to work on it anymore and I'm not driving it. I was thinking exactly what you recommended about replacing the brake booster next since it was full of brake fluid which we know is not good. Hopefully tomorrow after work I can get that done. The brake fluid was up to the bottom of the hole where master cylinder goes into the brake booster so it has been leaking for awhile looks like. I will post an update and let everyone know the outcome.

 

I found this on the web today. It goes with what you said Nullhead, replace both master cylinder and booster.

http://my.cardone.com/techdocs/PT%2050-0001.pdf

JDA3120
PT 50-0001
Failed Booster Seal Causes Master Cylinder Leaks
Vehicles equipped with power brake booster assemblies.
Chronic master cylinder failure due to fluid leaking past secondary
seal in the master cylinder bore.
A defective master cylinder pushrod seal in the power brake
booster allowing vacuum to draw fluid past secondary seal of
the master cylinder.
Replace both master cylinder and power brake unit.

 

So today I got the new brake power booster installed. I had to call the dealer with my vin to verify my brake system type which is JF3 to make sure that I got the correct booster. With the new booster installed now my brake pedal feels normal. I did a test drive and it feels like the brakes are still dragging so I jacked up the front and checked both wheels and the brakes are still dragging. I was able to unbolt the master cylinder from the booster and move it over enough to get the booster off and on without having to disconnect the brake lines so I did not bleed the brakes again. After finding the brakes are still dragging I pulled the ABS fuse and did another test drive then jacked up the front. Turning the tires by hand the brakes ar still dragging on both sides, it did feel just a little easier to turn but still not free spin ting by hand. I don't know what else to do at this point. Anybody got any suggestions?

 

I have been doing more online research for this problem and instead of searching for Silverado I just searched Chevy front brakes not releasing and I'm finding info for other Chevy models having this issue. Most of the post do not have a final comment to what fixed the problem. Some research I found said that there could be air in the ABS system causing this problem and you have to do a pressure bleed of the brake system using a computer connected to the truck to open the ABS when bleeding the brake system. I called a local shop today and the guy told me that the have the equipment to do that and would charge me $40 which is a diagnostic fee to do this. I'm taking the truck to them hopefully tomorrow. The guy at the shop said the same thing about having air trapped in the ABS can cause the brake to stick. I will post an update to let everyone know the results.