Help needed Brake problem

[sacha1001]

Hi guys hope you can help, this one has got me baffled.

Audi A4 B8 2.0 TDI S-line 2008.

Ok Changed out the front and rear pads over the weekend and now I have a soft brake pedal that travels to the floor when engine is running, at first I though air might have got into the system somehow so used my easy bleed and flushed the system out but no change.


When engine is not running the brake peal is rock hard with no movement at all even with a good amount of pressure on the pedal, but when engine is running the pedal is soft and will slowly travel to the floor.

My first thoughts are master cylinder but how can the brake peal be hard with no movement at all when engine is off ? but when engine is running the pedal is like a wet sponge.

I would be most grateful if you can help in this matter, I have MOT due soon and need to fix this problem.

Also if you think it is the master cylinder where is the best place to get one?

Thanks again in advance.

 

[NHN]

Welcome to the site.

Assuming brake fluid lid was left open & the rears were done properly, as in the epb was operated properly to tighten the calipers up before using the pedal, iirc that's how its done as I've done this on another car without issues.

There was a thread recently on the rears/epb.

Assuming when bleeding liquid level was always at a high level.

 

[sacha1001]

Yep all done correctly.

As said can not work it out, rock hard pedal with engine off but when running pedal goes to the floor

 

[NHN]

You didn't wind anything back without the lid of did you, as maybe its damaged a seal.

 

[sacha1001]

You didn't wind anything back without the lid of did you, as maybe its damaged a seal.

No
lid removed
Then open up bleed valves then epb open with pc and pads changed out , rear pads closed with PC.

What I don't understand is pedal is right at the top and rock hard without engine running, if seal had gone then the pedal would be soft all the time ?