Im experiencing a little different symptom, my brake pedal gets soft when I press the clutch pedal.

Already bled the brakes with dot4 by the book and still the same, calipers are dry, no visible brake fluid puddles, could it be the master cylinder?

Another question, a faulty brake assist or vacuum leak could cause a soft pedal?

 

Add the required car information.

 

Sorry, its a 93 eg d15b2 dpfi

 

Replace MC and go from there.

 

Yes, im pretty sure its that, made a quick test drive just now and the clutch pedal in fact doesnt make any diference.

What happens is, if a hit hard the pedal, it breaks ok!

But if I press it easy with little force, in 4-5secs, it will hit the floor. This happens with engine on or off, more easily with the engine on prob due to the brake assist.

So if the piston of the MC moves fast, generates pressure and the brakes stop the car, but if the piston moves slowly, no pressure, no brake.

Is my thinking correct?

 

Ok, I'm just bringing the good news, changed the master cylinder, breaking is great again!

The give away in my opinion was "if a hit hard the pedal, it breaks ok!

But if I press it easy with little force, in 4-5secs, it will hit the floor. This happens with engine on or off, more easily with the engine on prob due to the brake assist."

Also, is very important to bench bleed the master cylinder very carefully.