Brake pedal goes mega hard whilst driving. Mega scary PLEASE HELP!!

[dubstar81]

My brake pedal goes really hard when whilst driving. I give it a good rev and the brakes come back. Ive heard that there is a servo vacuum pipe connection at the firewall/bulkhead that collapses inside causing a loss of servo operation, apparently there is a modified part.
Does anyone know the part number at all?
It is a 2002 a4 tdi sport 130 bhp 6 speed.

[arman123]

Check you battery area plenum chamber for water the drain holes get blocked and the brake servo get water damage some people have up to a couple of inches of water there if no water check your vac lines to servo for damage

[a4eire]

Hi,
I had the same problem this time last year with my 2001 a4 tdi sport 130 bhp and had a few lucky escapes. It turned out that there is an issue with the plenum chamber filling up with water and not draining away. This resulted in the Brake servo filling up with water and causing the inside of the servo to corode. I contacted Audi here in Ireland and explained what was happening & it turned out that there was in fact a recall for this issue. They took my car and after examining the braking systems they concluded that there was in fact 'Consequental damage' caused from water entering the brake servo and in fairness to Audi they covered the replacment of the Brake Servo, hoses and Vaccuum pump plus all labour....So well worth looking into!!!

[JohnyIre]

I don't have the servo issue... yet... but my windscreen is getting very fogged up with the last few mornings, so I assume the drain plugs are blocked in my car. I might contact Audi here in Cork and see if I can knock free labour out of them. I could do it myself but if they're willing to do it for me all the better!

[SWARCUP]

There is a recall to audi for the plenum chamber drain grommits so call audi and ask them to check if your car has been done, its all free by audi it only takes them a couple of minutes i think they just pull them out, in all fairness something that you could do at home

[JohnyIre]

Do they just pull them out or replace them with anything new? If they are just pulled out, I wonder why they are there in the first place.

[SWARCUP]

They are there to prevent dirt/water etc from going upwards into the plenum from the road. I dowt that will be as bad as leaving them in

[RuslanA4]

Hi there, JohnyIre! I was just wondering if you've contacted Audi in Cork and what outcome have you got? I'm in Ireland too and having similar problem with my 2001 A4 2.0.
Cheers

[JohnyIre]

Not as yet, I have a window winder and small potential water leak to look at first. When it rains it pours!