Spongy brake pedal

[laalves]

For quite some time the feel of my brake pedal (02 TT) doesn't feel right, spongy and easy to reach the bottom. Stopping power feels ok, but need to go deep on it.

 

Brakes were just bled at the dealer, no change in the feel. I didn't discuss any of this with them, as I'm used to do all my corrective maintenance and only let them do the minimal scheduled so as to have the stamps on the book.

 

Having another person pressing the pedal whilst I look at the Master Cylinder/booster/ABS pump area, engine off, there's lots of unexpected noises: clear spring noises coming from inside the MC and bubbly/squishy noises that appear to come from the lines going into the main ABS controller unit. No leaks are visible anywhere. No bubbles are visible on any of the unions.

 

Another thing that has puzzled me for a while, is the appearance of drops of hydraulic fluid on the surface of the fluid reservoir. Some ends up collecting in the channel surrounding the reservoir. It's as if it is leaking through the cap, although I have replaced it with a brand new OEM cap.

 

The level of the reservoir does not go down with time, never had to top it with fluid.

 

Anybody had any of these symptoms? I'm tempted to either replace the MC (750€, not a trivial cost) or to take it out, open it and check the seals. Not sure about this option either because I may end up buggering a good and expensive thing and not solving the problem.

 

Edited February 11 by laalves