Brake pedal goes to floor when car is running?

Hi,

Did you bleed the ABS? The ABS portion of the brake system must be bled separately using a bidirectional scanner.

Take a look below. I attached the directions. Let me know if this is something you can do or have done.

You likely have air in the system.

Let me know.

Joe

See pic below.

Hi,

Did you follow the sequence listed in the directions? It indicates a standard bleed, then the ABS, then a standard bleed again.

What you are describing is either air in the system or a bad master cylinder. I've seen situations where the push rod between the booster and MC wasn't properly seated causing similar issues. Everything went back together easily, correct? Also, before installing the new master cylinder, was it bench bled?

Let me know.

Joe

Hi,

If the booster was causing the issue, the brakes would lock up if they went to the floor. That isn't the case. Are you able to pump up the brake pedal if the booster is connected? I ask because all the booster does is provide assistance (which makes it easier to press).

Let me know.

Joe

Hi,

When you bled the ABS, was it done via the data link connector with a bidirectional scan tool? That's the only other thing that makes sense.

Joe

It isolates the problem gently take four vise grips and close off the flex hoses that go to the wheels to see if the pedal stays hard, if so the problem is a the wheels if not the problem will be with the master. Did you bench bleed the master, if not this can be the problem here is a guide and a video to help us with the problem. Also, when you say you bled the ABS did you open the ABS valves?

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

and

https://youtu.be/nQRnKyVyMuQ

and

https://youtu.be/WDxvEQrMkBg

Please go over these guides and report back.