Bomb change brake still hard

[maRS2]

I just change the bomb on my car for a brand new one.

So made the test after fiting it and just 3 brake pomp and the pedal get's rock hard.
Tried also with engine on and after 5 braking pomp pedal is rock hard and almost no travel.

I cannot do all the test from sjm as I never got any warning light's coming on the dashboard.

So do you think I should change now the pump or would it be the hydrolique servo (booster amplifier)

the pedal feeling is most of the time very hard need a lot leg strenght yo stop the car.

Pump make lot of noise when hot.

If I keep on pressing the brake pedal it go slowely down and down untill bottom after a minute or so

[robinm]

Sounds like there may be several problems. Both with servo side and brake fluid side.

For the pedal going hard quickly - the noisy pump (use screwdriver trick) sounds like a dead give away. Seems like it's not generating enough pressure/volume. BUT to test it properly you need some special kit to measure the flow rate and pressure. I changed out a noisy pump in my S2 and I still get the warning light at start up. I still need to test the servo.

The pedal slowly going to the floor is another thing though I think. Could be master cylinder or a leak somewhere else. A brake fluid leak, not hydraulic fluid.

I reckon it would be worth getting the warning light to work. There is a test for the pressure sender somewhere on S2 central.

[maRS2]

Finaly get the time to make the Brake booster (servo) test and mine is leaking.
So it's dead.
I should have done this test before just take 5 mn.
The part is very expansive from the stealer about 700€

Buying a second hand one might be lost of money as all the one from S2/RS2 will be very old and might give up soon.

Is theire more rescente car with the same brake booster? S4B5 may be?

[robinm]

mars2, not sure about other cars with the same servo.

How did you undo that pipe union on the top of the servo? I can't get a spanner on it at all, even with the brake fluid reservoir removed.

Robin

[maRS2]

On the RS2 just need a 19mm spanner no problem
My car is LHD

[maRS2]

picture of it

[AAH!]

Is the return line that you have to undo on the servo for the test, the one by the firewall behind the brake fluid reservoir. It looks like more than a 5 minute job on my car. maybe it is easier on a LHD.

[maRS2]

AAH on the picture above you can see the spanner 19 sitting on the return line.

Its the only hose going back to the Tank on my servo

[maRS2]

AAH! My brake booster look very different from the one you show on your drawing

[AAH!]

mars2, not sure about other cars with the same servo.

How did you undo that pipe union on the top of the servo? I can't get a spanner on it at all, even with the brake fluid reservoir removed.

Robin

Same for me.

The RHD servo it is very different to your LHD one.

Angus

[robinm]

Yeah, very different. On the RHD S2 the pipe is right up against the bulkhead (firewall) and there are lugs on the servo that make it difficult to undo the nut without knackering it. I think a special pipe spanner would need to be ground down to fit on.

[maRS2]

If some body have ekta it would be nice to tell me the part number of my brake booster (servo) on the picture.

I think it's number 30 on the etka page but can't get the Audi part number

Thanks

[Corey]

Depends on chassis code but for LHD you have 2 part numbers available

8A1 612 099 or
8A1 612 099A this one is from chassis code F8C-S-000369

[maRS2]

Thanks Corey

Just missed the end of a GT3 caliper bid on the bay because i arrive to late home.
Next one in 2 day's

[maRS2]

I finaly change the Brake booster ( servo).
What a diference!!!

-now I have a powerfull pedal feel.no more wood pedal feel.
-Before also if I was stoping on small slope the car wouldn't move even after I release the brake, like if it was never releasing totaly the brake.
- now as as i release the brake even on very small slope the car move.

I should have done this much earlier.

Only thing my brand new bomb can still only get 5-8 pump before the brake get hard even with the engine on. May be the PAS doesn't deliver enougth pressure.