Spongy brake pedal (master cylinder)?

[Diggy98]

Hello guys, since I bought my a4 I have noticed that the brake pedal is spongy and I have to press it almost on the floor in order for the car to brake. I would like to sort this out in the shortest possible time since there are the brakes we're talking about here...Reading on the internet I found out that it may be the master cylinder on the brake pedal but i would like to know if I should buy the black circular tank where the cylinder is installed also. I'm asking this because I don't want to be ripped off by the mechanics in my area, also I have some experience with brake jobs so I'm considering replacing it myself. Thank you in advance!!

[Magnet]

Hello Dragos,

I think you are wise in getting this sorted as soon as possible - knowing how these Italians are supposed to drive! No offence!

Main question - no, you should not need to replace the (the large black circular tank) servo. 

The brake pedal travel could be a master cylinder fault, but it could be other faults in the braking system. Check the braking system carefully at each wheel with an assistant pumping the brake pedal to get as firm a pedal is possible. Look for things like bulging rubber brake hoses , brake pads etc.etc. 

If you are happy that all is well with everything else then it is likely to the the master cylinder as you say.

Kind regards,

Gareth, 

[Diggy98]

Thank you very much for your quick response, Gareth! Everything else is ok, pads and rotors are like 80%, hoses are good and I have no fluid loss, so I guess it should be the cylinder. I will try to replace it as soon as possible. Cheers!

[Diggy98]

Also, does anybody know what role does the circular tank have?

 

P.s. I got it, it's the servo.

[Magnet]

You are very welcome Dragos. 

"Pedal almost on the floor boards" ? "Will try to replace it as soon as possible". Yesterday would have been great Dragos! Still, we rest peacefully in the knowledge that you are in Italy! 

I guess we would remiss on this forum if we did not advise you not to use this car at all until this problem is safely sorted. Just covering our bums over here.

Kind regards,

Gareth. 

[Diggy98]

Gareth, I haven't been using the car for the last two weeks and I think I won't be using it next week either. "As soon as possible" means when I will have some time to get to the car and work on it. Thank you for your concern anyway!!

[Rob82DZL]

Hi Diggy98,

When you inspected the brakes have they all been bleeded as well? That would be a good shout before you start looking into replacing parts.

[Diggy98]

Hello Rob, thank you for your answer! I did the bleeding two or three times, abs included.