Alright guys I hope you can help me. Trying to fix my brakes. New master and booster installed and when I press the pedal to bleed brakes the idle goes up and no resistance to bleed. Booster vaccum hose is new when I do open bleeder fluid comes out and no air. Yet still no pressure build up. I am stumped,,,, I would think master is bad but its brand new. Also why would the idle rise if it was just the master that was bad. Please someone give me a quick reponse even if its just guess I need to solve this tonight..... thanks in advance I know you will all pull through. Another quick note. At times it will build good pressure then go away.

 

Ive never replaced a master before myself, but i think you have to bench bleed the master before you put it in the vehicle. and you may need to bleed the abs module too if you replaced the master, im not 100% sure but i think this requires a scan tool

 

I forgot to bench bleed and am sure that is an issue but I have been told that you can bleed the line connections after installed and it will get the air out. when I do this it only has fluid coming out so I am pretty sure I got the air out of it.

 

what happens if you pump the pedal up with the engine off? does it stay firm or does it loosen up after a few minutes?

 

My understanding of it is that the new master cylinder has to be bench bled before the install. There are no 'foolproof' short cuts I am aware of.