Caliper stilll dragging

[Biznessthyme]

2007 Sierra 1500 Classic 160kmiles
 

This topic seems to be somewhat covered but I’m at my wits end and reaching out to internet strangers

 

I screwed up and accidentally topped off my master cylinder with the wrong fluid. Ruined everything and the front calipers would begin to drag after just a few miles. 
 

flushed 32oz of fluid through the system then replaced the master cylinder and booster. I bench bled the master cylinder. Fronts continued to drag. Then replaced the brake hoses and calipers, bled, and the dragging brakes continued. Then replaced the ABS module, had the brakes power bled and the problem continues. 
 

Is there anything left to change, or something I’m not thinking of, or could it be that I didn’t clear all the bad fluid? Every bleeder seemed to be pumping clear fluid. 
 

interesting to note, I cannot recreate the calipers dragging in the driveway. I can pump the brakes, drive in reverse and brake, pull forward and brake and the dragging will not occur, I only happens when I’m out driving for a cpl miles at 45-50mph

 

the problem presents itself much quicker the warmer it is outside. 

[richard wysong]

Are you sure it's not the brake pads hanging up in the caliper bracket? Rust tends to build up between the anti-rattle clips and the bracket binding the movement of the pads. Another possibility is the caliper slide pins are frozen. Why would you replace the booster for brake fluid contamination?

[asilverblazer]

18 hours ago, Biznessthyme said:

I screwed up and accidentally topped off my master cylinder with the wrong fluid. Ruined everything

What fluid did you use?

 

Could have deteriorated the rubber flex lines or rubber seals in the master cylinder/booster.

[swathdiver]

On 2/6/2024 at 4:18 PM, Biznessthyme said:

flushed 32oz of fluid through the system . 

I went through six quarts to get clear fluid at each corner.  

 

I reckon that the wrong fluid is still in the system and it destroyed everything it came in contact with.

[richard wysong]

You should have pulled the master cylinder off before flushing the contaminated fluid through the whole system. In a normally functioning system the brake fluid doesn't travel very far into the system when you step on the brakes unless you have a leak or are way out of adjustment. What did you put in that wasn't brake fluid? James is correct , a quart of fluid  didn't flush it completely. Are all the brakes dragging or a single wheel or axle? you should be able to tell by the temperature of the wheels.

Edited February 9, 2024 by richard wysong

[Biznessthyme]

On 2/8/2024 at 8:44 PM, richard wysong said:

You should have pulled the master cylinder off before flushing the contaminated fluid through the whole system. In a normally functioning system the brake fluid doesn't travel very far into the system when you step on the brakes unless you have a leak or are way out of adjustment. What did you put in that wasn't brake fluid? James is correct , a quart of fluid  didn't flush it completely. Are all the brakes dragging or a single wheel or axle? you should be able to tell by the temperature of the wheels.

I used (much to my wife’s displeasure) the marinating syringe to get the fluid out of the master cylinder then top it back off with fresh. 
 

the front calipers are both dragging.  Wheels are definitely hot.
The rear drums are warm but the wheels aren’t. 

[richard wysong]

Hmm, Sounds like the master is not returning all the way. Try cracking a bleeder on the fronts while they are dragging and see if they release, if they do then work your way back to the master by cracking the lines before and after the ABS module then at the master and that should tell you where the problem is. If they don't release cracking the bleeders the problem is with the calipers