brake vacum leak and power steering issue

ErikLing

Member
I very recently bought a A2 1.4 petrol. The car has now developed a hissing noise under the driver side dash that seems to be affected by the brake pedal. i guess that this is a vacum leak in the brake assist. However I can not feel any change in the brake performance. At the same time as the hissing noise started the power steering also started to malfunction. The power steering is now temporary loosing power when driving. I have checked the fluid and it is topped up and in good condition. Can the two issues be related? And does anyone have any experience of the same problems?

All help is much appreciated!
 
Last edited:
I have started a teardown and it is very obvious that the leak is coming from the collet where the pedal engages the brake assist. This also affects the idle which I find a bit odd. Is not the brake assist driven by a electric vacum pump on this model? if so i am not quite sure how a leak can affect the idle. ill continue tomorrow and will try to demount the brake assist and remount the rubber collet and hopefully stop the leak.
 
The diesel models have a vacuum pump however the petrol brake servo does indeed rely upon engine vacuum. The leak will almost certainly effect the engine idle.

The power steering is unrelated, if you have VCDS it may be worth plugging in a seeing if you've got any fault codes.

Nick
 
I have started a teardown and it is very obvious that the leak is coming from the collet where the pedal engages the brake assist. This also affects the idle which I find a bit odd. Is not the brake assist driven by a electric vacum pump on this model? if so i am not quite sure how a leak can affect the idle. ill continue tomorrow and will try to demount the brake assist and remount the rubber collet and hopefully stop the leak.

Having vicariously been through the experience, I gather that you will need to lower the engine slightly to get the servo out. You will also need to remove the master cylinder from the servo (and probably from the pipes). It is not a job to be underestimated.


Sent from my iPhone using Tapatalk
 
Thanks!

Everything seems to be working out. I removed the servo and found that both the inner o-ring seal and the collet was completely loose. Since I did not experience any issues with the actual brake performance even with the seals missing I guess that the brake booster itself might be ok. I remounted the seals and the collet and will now bleed the brakes and do some thorough test driving in a safe place.

I disconnected the leads to the master cylinder and removed this. I was thereafter able to remove the servo. It was a tight fit and for a while I considered to remove the wiper motor assembly, but in the end I managed to pull it out without having to demount anything else. The most complicated part was acctually to remove the brake pedal. I made a makeshift tool to depress the two plastic wings securing the ball joint. It was very tedious and i managed to crack one of the plastic retainers somewhat. the ball joint still locks in place and I think it will be fine for now, but I might keep a lookout for a new pedal eventually.

My first 48 hours of owning an A2 has indeed been a bit cumbersome. I am hoping for a bit smoother ride ahead...
 
Back
Top