symtoms of a dodgy master clyinder??

[steveo29 0]

i have another post running regarding my low pedal after fitting mk4 calipers

 

i wonder if ive buggered the master cylinder

 

can someone describe what hapens if the m c is dodgy

[Bruno 4]

It really is dead simple. There are three symptoms:

 

1. The pedal is soggy. This could however originate from anywhere in the system, and will not go away until the relevant device is sorted. Often its the master, but you need more information than just this.

2. The master cylinder reservoir has mucky fluid. This means that it has allowed rubbish to back up the system and thats a sure sign that the rubbers have gone. But its also a sure sign that rubbers elsewhere have gone too because the muck had to get in somewhere.

3. When you pump the pedal vigorously, you will see a small stream of bubbles come up the reservoir to the surface. Thats the final nail in the coffin.

If you have ABS DO NOT change the master cylinder unless you have depressurised the car. ABS system pressures are phenomenal. Turn off ignition, disconnect battery and pump the pedal until it doesnt change anymore. This dissipates the energy.