Help! I have a 2007 hhr that I love. No rust no issues, except one. All 4 breaks lock up. They release after about 45 min. You go no where when this happens! I have had it to 3 “back yard” mechanics. We have replaced Everything brake related. ABS module, pump, break lines, breaks etc etc etc! Nothing has helped. This is my last hood before taking it to a Chevy garage and paying out the you know what! This problem all started after replacing the Master Cylinder. You think wow we finally fixed it! But after driving for about 45 min, you’re stuck. What could be the problem?

 

wrong master or issues with the master cylinder push rod length. if the rod does not have enough free play it blocks the ports in the master so fluid can't return properly. as the fluid get hot it applies the brakes more.
check the brake pedal free play

 

[QUOTE=tech2;487529]wrong master or issues with the master cylinder push rod length. if the rod does not have enough free play it blocks the ports in the master so fluid can't return properly. as the fluid get hot it applies the brakes more.
check the brake pedal free play[/QUOTE

This is the 3rd Master Cylinder we've put on it. There's no place to adjust the push rod length. I had thought the same thing about the length. But nowhere to adjust. I'll check the free play