Brake problems.

[No3ntry]

Had a problem with my brakes that my pedal would be very soft then hard immediatly after pressing it.

The mechanic diagnosed it as a faulty master cylinder

So i bought one second hand
My car is a 1994 V6 mondeo the new master cylinder came off a 1999 V6 mondeo.


The mechanic has replaced the cylinder for me and bled the system up about 5 times now.

the problem is this the brakes travel quite a lot and the braking snatches very badly its really really sensitive and i swear i am gonna give myself whiplash tomorrow on the way to work.


If i sit in the car engine running and pump the pedal it goes hard but then sinks to the bottom again if i keep my foot on the pedal.


So please help me what the hell is wrong with my car ?

Initial thoughts were wrong master cylinder BUT with pumping the pedal and it getting harder that points towards air in the system somewhere

 

[Dandle]

Sounds like your second hand master cylinder is knackered too. Pumping the pedal and it getting harder is more fluid being pulled into the system the fact it gets softer with your foot on it indicates that the fluid is escaping back through it(so your foot can push it to the floor). Things like master cylinders aren't worth buying second hand as they are cheap enough in the first place and can suffer corrosion if they get water into them.

 

[Dogbreath]

Sinking pedal is usualy faulty seals in the master cylinders, but can be caused by a leaking slave cylinder/caliper or pipe/union.