sanadrustom

Hey guys,

i have a nub question, how many ABS/speed sensors do the S6's have?
just two in the front or 4 2 front 2 rear? reason i ask is i'm facing a weird scenario where my brake peddle feels like the ABS is being engaged constantly. thought it was an air bubble in the brake line but i bled it and still nothing. or could it be something else? i can put my weight (200lbs) on the brake peddle while coming to a stop and the car just barely stops. i feel more of a pulse than a vibration on the peddle. Once the car stops i can press down and once it comes to a rest the pulsation stops. i have come to a conclusion that it can be something even more pricey than i expected could it be:

-ABS related?
-master cylinder?
-brake actuator(brake bomb)?

i'm simply running out of ideas and hoping someone can guide me the right direction

thanks in advance

sanadrustom

I should probably add that it's pulses even when it's stopped didn't have to be moving. In fact the pulsation gets faster as the rpms get higher so this is hydraulic pump related no?

GoHeels

Here's a link that might have answers for you - if you click on 1 of the first topics it will display in a much easier to read format
http://forums.quattroworld.com/s4s6/msgs/15186.phtml
There should be some info in there for you in the categories.

sanadrustom

From what I have read (below I copy pasted) the symptoms are indicating that my bomb is not holding any charge at all..im gonna do a few tests check the hoses and what not before I go all out and buy a new bomb (kinda pricy)

Thank you goheels for the awesome link

Cheers



The brake light comes on when the system pressure is low. If it takes 10 minutes of highway driving before the light goes out, the bomb is not re-charging fast enough. This can be caused by restrictions in the lines, a weak pump, or a really leaky servo. Even if the bomb is bad, the system should pressurize rapidly. Ditto the hard pedal after repeated brake applications - either the bomb is bad and not storing enough charge, or the system isn't re-pressurizing the bomb fast enough. I'd suggest the following:

1. Test the bomb: Run the engine until the brake light goes out. Shut the engine off. Pump the brakes until the pedal gets hard. Count the number of pumps - you should get at least 10. A new bomb gives 30+.

2. Test the servo: Run the engine until the brake light goes out. Shut off the engine. Remove the servo return hose at the hydraulic reservoir. Pentosin should not be coming out of this hose. More than a few drops indicates a leaking servo which is discharging the bomb back into the reservoir.

3. Test the bomb check valve: Pressurize the system by running the engine until the brake light goes out. Check the Pentosin level in the hydraulic reservoir. Let the car sit overnight and check the Pentosin level again. If it is higher and the servo is OK, the bomb check valve is leaking, allowing Pentosin back into the reservoir and discharging the bomb. This is a common problem in the S-cars.

4. Discharge the pressure in the system by pumping the brakes at least 40 times with the engine off. Remove the banjo bolts in the hydraulic system and examine closely. Some of these bolts have a fine internal screen in the oil passages. The interior of the hydraulic hoses can break down with age, and the rubber particles clog these screens, restricting oil flow, which in turn prevents the bomb from recharging rapidly. This is a good opportunity to flush the Pentosin if it looks dirty. Make sure you remove and clean the screen in the reservoir.

If the bomb & servo are OK and the lines are clear, your pump may be weak.

sanadrustom

finally after months of being in the garage collecting dust i decided to replace the bomb, and what you know the beast is alive once again. Putting insurance on it and gonna sell my allroad (has tranny issues) and drive this baby.

thank you all for the help im sure ill be back on the forms with other issues im sure of it 100%

Cheers!