Bleeding brake system!

**day** · 11-11-2007,10:47 PM

Hi All

I am new to this forum and wonder if anyone can help out!
I have a golf mk4 1.9 gttdi

I've just had to replace my back brake discs and pads - Although never done it before thought i would give it a go.

Changed the discs and pads fine and then it came to trying to bleed the system. I bought one of those one way valve kit to bleed it and i have done all 4 corners but something is still not right.

The braking is still really really spongy and the light on my dashboard telling me to check brakepads is still on. i bought new brake fluid and everything and now i just dont know what else to do.

Is it a case of just bleeding it again? am i doing something wrong? please can anyway help!!!!

**Wasptuning** · 27-12-2007,08:24 AM

Bleed again, you still have airbubbles.

**Col** · 27-12-2007,12:48 PM

For some reason the VAG systems seem to be very sensitive to the old fashioned pedal pumping method i.e. it doesn't work.

If you do have another go and it still doesn't work, try a pressure bleeder like the Gunsons Easybleed (from Halfords).

Hopefully someone like Crasher or A8tech will be along to offer their wealth of experience on this.

**cavanagh81** · 14-04-2008,09:19 PM

hi im having same problem having just fitted abs pump, ive even pressure bled system using easy bleed kit and have reverse bled using electric pump and have bled bleed screws on master cylinder but still got soft spongy brakes. When engine is not running brakes pump up hard but when started and servo kicks in go soft again, ive now bled system 10 times and am sure there no air in system, has anybody got any more ideas , Thanks.

**Nutty** · 14-04-2008,10:22 PM

Are you sure you have adjusted the rear brakes correctly ? leaving the pad to far away from the disc will give you a spongy pedal, feeling like there is air in there, it may just be the piston having to travel to far in order to apply the pad to the disc..

**Borab0y** · 15-04-2008,08:36 PM

dont forget the new pads have to bed in aswell, maybe causing some of it.

**Col** · 15-04-2008,08:47 PM

Originally Posted by cavanagh81

hi im having same problem having just fitted abs pump, ive even pressure bled system using easy bleed kit and have reverse bled using electric pump and have bled bleed screws on master cylinder but still got soft spongy brakes. When engine is not running brakes pump up hard but when started and servo kicks in go soft again, ive now bled system 10 times and am sure there no air in system, has anybody got any more ideas , Thanks.

If you have changed the abs pump, you need to set it so that it goes into its bleed mode. To do this you need vagcom or similar.

Look in the vagcom subforum for details of either setting yourself up with it or to find someone with who can help.

**cavanagh81** · 15-04-2008,09:41 PM

hi thanks for all feedback, i have vag-com software and data cable is it possible to do with this and any idea how ?

**jonathanfenton** · 19-09-2016,04:28 PM

Just out of interest how do you bleed the master cylinder?

**FrenchAudi** · 19-09-2016,05:58 PM

Originally Posted by jonathanfenton

Just out of interest how do you bleed the master cylinder?

If you are asking me, when I recently renewed the brake fluid I did not bleed the master cylinder as such, as the reservoir level was correct at the beginning, with no air in the m/cyl, and by bleeding fluid from each wheel cylinder in turn the fluid in the m/cyl was also renewed.

When fitting a new, empty m/cyl on a car without ABS, I fill its reservoir before installing it, then unplug each outlet union on it while pushing the piston gently in by hand with each outlet in turn at the top, to remove as much air as possible. I then install the m/cyl, connect it up, and bleed via each wheel until no more bubbles appear there.

I have not tried this on a vehicle with ABS, but fear that there will be a possibility of getting a small amount of air into the ABS unit. I assume that if this were to happen I would have to get the unit bled by a VAG dealer.