Dragging brakes

Purplejchild · June 6, 2020

I have a 2011 Chevrolet Silverado 2500hd 4x4. It has developed a dragging brake issue. I have changed all 4 calipers, brake pads,all brake hoses,master cylinder, and hydro boost, flushed with new fluid. It shows no check engine or Abs lights or codes. I can drive it between 10 to 20 miles and you can start to feel the brakes applying till it locks up. Then I get out and pop the brake line and relieve the pressure then we're fine for awhile till it starts all over again. I've taken a temperature gun to the calipers when its locking up and the front can be up to 180 degrees and the back up to 150 degrees, or it can be the back hotter then the front. I've taken it to a dealer and they have scanned it and with no codes they are saying it has to be a mechanical issue, but I have changed all the mechanicals except the hard brake lines. I am starting to think it's the Abs module or pump, but with no lights or codes I hate to put another 1000in this gamble. Any advice or help would be much appreciated. Thank you!

tlaw91 · June 7, 2020

You have to swap it over when you change the cylinder.
Unfortunately with the way this whole deal shook out, unclear if he
A. Needs ABS module
B. Left contaminated oil in system when changing parts (unknowingly) and a new part is bad
C. Did something incorrectly, or some combo of the three.
When you’ve replaced the entire brake system other then the abs and it’s doing the same thing ur options are limited. And yes abs modules can do this.

Purplejchild · June 8, 2020

I think I might have a breakthrough. I drove it today and it started to drag to the point it was almost locking up. I got out a d loosened the master cylinder from the hydro boost and that released the pressure, so I drove it home loose and put washers on and drove it the rest of the day and no dragging. So I hope this did the trick. Thanks for your advice and help...

tlaw91 · June 8, 2020

Sounds like pushrod length issue. Glad we helped, that was a tough one. Hardest issues I’ve ever had is when you fix the issue but then cause another with the same symptoms. I hate cars.

Purplejchild · June 8, 2020

How could the length change and cause an issue?

tlaw91 · June 8, 2020

Always pushing the brakes ‘on’ just enough I mentioned it a few posts ago

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Doug_Scott · June 10, 2020

It sort of defies logic. The push rod getting longer would be going against physics. If the jam nut came loose, I would expect it to get shorter since becoming longer means it has to overcome the static pressure in the master cylinder. You will want to unbolt the master cylinder and slide it off the studs so you can take a look at the push rod. Having never seen behind a master on a hydra boost system I am just assuming the push rod can be removed this way. The push rod should have a lock or jam nut preventing the rod from turning on its threads. Be careful to avoid losing the current installed length. Using washer as you did is a good way to help diagnose it, but is not wise to leave it that way. You sure this didn't start after the master was changed?

Purplejchild · June 10, 2020

I know I'm scratching my head also. The dragging of brakes is what got this all started. There was 2 stuck front calipers that might have been the original problem, and after fixing that mybe the pushrod might have continued the problem. I don't know...

BrianBrianBrian · January 30

On 6/9/2020 at 9:47 PM, Purplejchild said:

I know I'm scratching my head also. The dragging of brakes is what got this all started. There was 2 stuck front calipers that might have been the original problem, and after fixing that maybe the pushrod might have continued the problem. I don't know...

Man...
I am so happy to have found your post. I've been trying to solve this exact problem for the past month.
This was my post <---

After replacing the Brake pedal sensor switch, Front: Wheel hub Assembly, Rotors, Brake Pads, Calipers, and I even replaced the trailer brake module for the cherry on top. And just like you, the damn brake drag is still there. I've been trying to explain this to everyone and it feels like I'm the only one with this problem until I read your post. I've only been able to drive locally before it gets so bad that it almost seizes. Like you, no codes have been thrown that I can relate to the issue. The next step for me was to replace the brake hoses and then the MC. But since you mentioned you performed these steps I'll skip it and put the $$ towards the GM technicians. I just dropped her off yesterday and the guy said he doesn't seem to think its a brake problem, but more likely an electrical problem. Said they'll need the truck for a few days to comb through the wires...(sounds cheap, gulp)

This is old post but hopefully you can share your memory of the final fix?

Edited January 30 by BrianBrianBrian

Bowtied13 · May 18

BrianBrianBrian what’d you find out from the dealership? I’m dealing with the same thing in my truck.

beachboi · July 5

On 6/7/2020 at 10:11 AM, tlaw91 said:

Contaminated hydroboost systems aren’t common but they do happen.
I’ve also heard abs modules staying ‘on’ and holding brakes.
Also,
Double check pushrod length/adjustment, make sure there’s free play in the pedal, if the rod is too long, or adjusted too far in, it’ll hold the pistons inside the master beyond the compensator ports and never let pressure bleed off after applying brakes

Would the pushrod come out of adjustment on its own?