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George H.
George H., ASE Certified Technician
Category: Chevy
Satisfied Customers: 18827
Experience:  GM Tech ASE Master Tech 15+ years
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Just change master cylinder and vacum booster, brake are

Customer Question

Just change master cylinder and vacum booster, brake are slowly locking up . but if the truck sit they release.had a air leaking sound under the dash.Brake were spungee so i change them
JA: How old are the hoses? And what driving conditions do you most often encounter?
Customer: truck is 2003 and it travels about 30 miles aday
JA: What is the model of your '03 Chevy?
Customer: trailblazer LT
JA: Are you fixing your Trailblazer yourself? What have you tried so far?
Customer: Fixing myself . I put a new Master cylinder and A vacum booster on checked the lenght of the push rod in the booster . when I drive it about 20 mile the brakes slowly start to ingage with out applying them
JA: Anything else you want the mechanic to know before I connect you?
Customer: I have had to drive it a distance to get it home with the brakes dragging. we can do this in the morning
Submitted: 1 month ago.
Category: Chevy
Expert:  George H. replied 1 month ago.

Hello I will help,

When the brakes lock up loosen the master culinder bolts and see if they release, if they do adjust the booster rod length shorter or shim the master away from the booster.

Please let me know what further questions you have, if nothing further please complete the rating

Thank you

Customer: replied 1 month ago.
No, I took it off with the brake hooked up put it Bake brake were still looked up ,
Expert:  George H. replied 1 month ago.

So when you removed the master from the booster the brakes (all of them) are still locked? Is the piston all the way back in the master when you do this? It should be back against the snap ring where to push rod touches the master.