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Discussion Starter #1
Any insite? 99 mustang gt vert with abs, My driver side front caliper will not release line pressure when brake pedal is released. (locks up tire while driving) will only release from rotor when bleeder screw is cracked and pressure released via that way. Caliper is good, remain just put it in because pistons were locked up in old caliper.( i think the root cause was the same problem as this) Slider moves freely. New rubber line, seen old one was not collasped upon removal. new fluid, bleed line 4 times. What the heck? What do i check from here and how do i check it? thanks a million!
 

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you answered your own question.

If the caliper only releases when you open the bleeder. You have junk in the caliper somewhere clogging the passages. Its not unheard of to get faulty parts from the store, Id try another caliper and another new line, and Id flush the brake fluid in the whole system before putting the new caliper and line on
 

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Discussion Starter #4
I will have to do it again in the garage, its locks up to hard to get it to a shop. There is nothing else that would prevent the line pressure from backing off? Proportioning valve, booster, etc?
 

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I will have to do it again in the garage, its locks up to hard to get it to a shop. There is nothing else that would prevent the line pressure from backing off? Proportioning valve, booster, etc?
If only one wheel is effected. it almost has to be the caliper. I've seen a rubber break line to the caliper collaspe on its self and not realease pressure.

If it was the master cylinder, P valve, etc. more than 1 wheel would be locking up. Maybe theres dirt in between the ABS and that wheel since it comes out of there seperate for each wheel.
 

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Discussion Starter #6
If only one wheel is effected. it almost has to be the caliper. I've seen a rubber break line to the caliper collaspe on its self and not realease pressure.

If it was the master cylinder, P valve, etc. more than 1 wheel would be locking up. Maybe theres dirt in between the ABS and that wheel since it comes out of there seperate for each wheel.
I see the abs sensor, but not sure where the abs is on the brake line system?
 

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Discussion Starter #8
I just got the remain caliper off again, was going to pull out pistons to look at them. Are they supposed to come strait out? because I am not having any luck getting them out. Any tricks?
 

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they shouldnt just come right out, but it shouldnt be much trouble to twist them and pull them out of the caliper bore.

Undo the line from the caliper, step on the brakes, see if fluid comes out. If not, undo the line at the body at the hard line, step on the brakes see if fluid comes out.

If fluid comes out of the rubber line at the cailper, then the problem is in the caliper.

Its not uncommon for the inner hose of a brake hose to collapse/go bad and look totally fine on the outer hose/cover
 

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Discussion Starter #10
Brake lines good, exchanged the rebuilt caliper for another one. Also bleed the brakes a little different this time. I used a stupid one man vacuum pump before. Its not sticking anymore but is slightly dragging. that rotor is burn your finger to the touch whereas the others are just warm..
 

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make sure you grease the slides also
 

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Discussion Starter #12
I did, thanks for the reminder though. The other day while downtown in stop and go driving, it stuck again. This time i could feel 4 inches or so of free pedal before pressure, went to work. After work the pressure was back and free play was gone.?.?.?.....
 

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Discussion Starter #14
Forgot to update this, Problem has been fixed for about 10 months. Root cause ended up being the master cylinder. Easy fix, purchased a remain form shucks, thanks everyone for your help.
 
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