My brake pedal feels soft and goes all the way to the floor slowly when standing on a red light. I suspect the master cylinder is bad; but I'm not sure. Another possibilty is brakelines- since the car has 181k on the odo I suspect they are starting to die as well. So my question is should I replace master cylinder? or is it something else?

p/s: And no, I don't think there is an air in the system, cause I bled them twice

 

Word of advice for future reference. Always start with the little things first before you move onto the more complicated expensive part. Did you check the hydraulic fluid level. Have you bled the brakes? You might have a leak somewhere or possibly air got into your brake system, check your pads as well. Just check everything before you consider buying additional parts.

 

Yes, GSstrencth, I did all the things that you said: replaced the rotors and pads, replaced two rear calipers and bled the brakes several times. Fluid level is normal.
Does anyone can tell me the signs of a bad master cylinder?

 

[QUOTE=nick_auto96;5960426]My brake pedal feels soft and goes all the way to the floor slowly when standing on a red light.
you named the #2 sign for a bad m/cyl. #1 is goes straight to floor. of course these could be signs of any leak in the system. so you have to CHECK everything. the m/c could be bypassing internally & not show any leak. look for fluid leaks everywhere ie: calipers,hoses and metal lines. better safe than sorry!!

 

Sounds like the Master Cylinder.