Brake pedal to the bottom when standing still- common abs unit prob?

[EvenM]

Hello.

I have been searching and reading the threads here about problems with the bomb and the brake servo. But I still cant figure out my problem.

With the ignition off, I can pump the pedal many many times, over 40 times and it dont get rock hard, maybe that is a problem itself?

When I start the engine, I push the pedal with normal or a little harder than normal pressure and the pedal goes slowly (almost like a step by step feeling) to the bottom, and after repeating this 4-5 times the warning light comes on and beeps. If I pump the pedal many many times before starting the car, I can push the pedal to the bottom maybe 7-8 times before the warning light comes on and beeps. So should have something to do with pressure??

I took of the return pipe on the brake servo, and some fluid came out, but how much is more than normal? Under is a picture how much that dropped down (wet spot)





I also have some signs of oil on other hydraulic pipes, dont know if that is a problem?

[EvenM]

Any thoughts ?

[mike74]

Is your hydraulic fluid reservoir at the correct level and not losing fluid? Its a closed system so the level shouldn't drop at all although, the level when at cold compared to hot does change.
Maybe the fluid level is dropping too low when the engine is running?

[Mikes2]

The return pipe should only be losing a few drips - more than that points to a leaky servo

[EvenM]

Thanks for your reply The hydraulic fluid is correct, and does not change

Is your hydraulic fluid reservoir at the correct level and not losing fluid? Its a closed system so the level shouldn't drop at all although, the level when at cold compared to hot does change.
Maybe the fluid level is dropping too low when the engine is running?

[EvenM]

The return pipe should only be losing a few drips - more than that points to a leaky servo

Thanks for you reply Aha, it came more than a few drops, but not " a continuous flow" as s2central write on his page. Even if its just a little leak it will have the effect I describe?

[EvenM]

Hope I can bump this and gets some more suggestions, have Norwegian MOT next week

[Mikes2]

Pumping the pedal with the ignition off empties the bomb - all fluid should return to the reservoir.

Does the fluid level rise when you do this ?

if not, it has be going somewhere and it's probably the servo

[EvenM]

Pumping the pedal with the ignition off empties the bomb - all fluid should return to the reservoir.

Does the fluid level rise when you do this ?

if not, it has be going somewhere and it's probably the servo

Thanks, will check it out I think its the servo or the bomb, will be interesting to find out

[Audi_CQ]

Sounds like a defective master cylinder seal.

[newsh]

Or the bias valve

[EvenM]

Sounds like a defective master cylinder seal.

Or the bias valve

Can I check if they are defect in any way?

[Audi_CQ]

Can I check if they are defect in any way?

The brake system is a closed system so if the brake pedal goes to the floor and you have no leaks, you either have air in the system or fluid is leaking past a seal in the master cylinder.

[Stick Insect]

I have a similar problem, the pedal 'bite point can be low or high. It seems to be linked to heavy power steering and a howling PAS pump. I will investigate further.
The steering and the brake servo on my car are hydraulically powered. It's a 1990 7a 20v quattro

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