.07 LT. Breaks where locking up ,felt as if the emergency brakes where on, My Mech said it was a bad Caliper , so he replaced the passenger side with a used one from the junk yard and replaced New hoses/break-lines , 3 days later Problem repeats again ,So I take it back to Mech, He replaced master cylinder witha New one , it seemed to work a few days then�� , it happens again.... I'm driving back to show him and it goes away, its working fine again ...... what do you think could be happening ��..............?
Mech is telling me to change the both calipers again with New ones , and possibly the proportioning valve , does the HHR have one ?

 

Not if you have ABS.

There is only 1 master cylinder.

Did he even look at the rear brakes?

Any warning lights come on?

Do the brakes just up and lock up, or do you step on the pedal.

is there a strange noise when this occurs?

too many more questions.

 

No error lights , no noises , just draged like if the brake was being pressed or the emergancy brake was on , you can smell the front brake burning getting hot , ....back brakes seemed to be OK

 

I don't know what could cause the problem described. I would advise against using used calipers unless they get rebuilt, but he could have rebuilt the old ones easily enough. Rebuilding calipers is a dead art.

If they are hanging the cause would more likely be the slider pins, which were probably not replaced or repaired.

 

Calipers are usually rebuilt and include calipers brakets and brake pads

https://www.rockauto.com/en/catalog/...b,caliper,1704

 

Is this a right hand drive car? Master cylinder is usually on the driver(LH) side.

 

The brake hoses that go to the caliper can fail internally and not allow the fluid to return to the master cylinder. If only one side is staying on and the caliper releases when the bleeder is opened it is likely the hose.

 

They said they replaced hoses.

 

I agree with Don here. I would remove the slider pins, take them to a wire wheel, clean them off, dip or coat them in Anti-Seize or high temp grease, and see if that resolves the issue...

But the first thing that came to mind is moisture or worst case scenario, the Power Brake Booster (PPB) (which I have not replaced yet).

Try cleaning or replacing and lubricating the caliper slider pins, make sure the slider pin rubber boots are not broken or torn, and flush the slider pin holes out with brake cleaner (before inserting slider pins). Also, take your cell phone light and make sure there are no broken bolts or debreis inside the slider pin holes after flushing them out.

 

New doesn't always mean good. They can be bad from the factory. Cracking the bleeder screw will show if there is any pressure in the caliper. Another thing to try is pulling back on the brake pedal in case the linkage is binding.