ok so i have replaced my master cylinder cause it went bad. i followed all directions before i installed and bleed it right. everything was working good then i hit my breaks and let off and they didnt relaese all the way so by the time i got home both front rims where practiclly smoking. so this morning i went out and opened the bleeder valve on driver side and a little fluid came out and stopped i retightend and my breaks would work great for a while then back to the same thing? is it possible that maybe both my rubber lines have failed at the same time? and why is it when i release some pressure from driver side bleeder valve they both work fine again for a while? or could it be that i got a bad master cylnder?

 

bump

 

its possible. It has the symptoms of collapsing lines. change the flex lines. if they are original, they should be changed anyway.

 

It is either what //<86TA>\\ posted, or that the push rod from the booster to the M/C is too long. The rod is adjustable, usually by loosening a lock nut and turning the rod?

If the rod puts pressure on the M/C piston it closes off the relief port. Which in turn causes the issue you are having. Need to have just a small amount of clearance between the end of the rod and M/C piston.

RBob.

 

see i would have thought my rubber lines where bad but both of them at the excact same time is wierd and when i release pressure on driver side bleeder valve it would release pressure on both brakes? i just got home from autozone and traded my M/C in for a new one since it is still under warranty. if this dont work ill check the clearance between rod and M/C. and if that dont work ill buy two new rubber lines? i guess thats the only things it could possibly be right?

 

what are you talking about? there is no adjustment on the booster/master that i have ever seen or heard of. Or is this adjustment inside the booster?

 

ok just got it put on and went for test ride and they are working much better. seems it was just a bad M/C? but when i was bleeding the brakes i did the front wheels first then i went to the rear drivers tire and when my wife held the pedal down and i broke loss the bleed valve nothing would come out?? i tried it several times and i even pulled the valve all the way out and the pedal still didnt fall to the floor?? any ideas? i have already put a new brake line from front to rear and it has a new rubber hose in rear? why aint fluid getting to rear?

 

pumping the pedal is not the best way to bleed brakes, a vacuum/suction type bleeder will work so much better. It will take a long time to get the air out of the new rear lines by just pumping the pedal.

 

I checked the FSM, the stock booster is not adjustable for push rod length. However, GM carries a 'service' push rod that is adjustable. With that the rod length can be changed.

RBob.

 

interesting

 

i dont think u read it clearly?? when i have the wife hold the brake pedal down i relaese the bleed valve and nothing happens?? my pedal stays in same spot with pressure so i dont think its got air in it? they worked before when i put it on and bleed them?

 

i dont know a hell of a lot but id say you got a pluged line !