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Audi a3 brake hissing when pushed down?

Joody1 May 15, 2020

  1. Joody1

    Joody1 Registered User

    Hi guys wondering if someone could help me. When i was coming hone from work this morning, i noticed the brakes were hissing when i pushed them down and there was a slight hiss when in its normal position. Brakes feel fine but dont want to continue driving if its a major problem and lose all brakes while driving. Heard it might be the break servo, how do i go about this?
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  3. desertstorm

    desertstorm Moderator Staff Member Moderator VCDS Map User

  4. Joody1

    Joody1 Registered User

    Yeah its a very slight hissing sound after ive pressed the brakes and its gone back to its normal position but very loud hissing sound when pressing the brakes. Is this a simple fix or a job for a proper mechanic?
  5. desertstorm

    desertstorm Moderator Staff Member Moderator VCDS Map User

    Read the second link I linked above. Depends on your definition of simple fix. Requires engine to be tilted down and forward so you can get access .

    "The way I choose to do it, which may not be the quickest or easiest but worked fine for me;
    Remove engine cover,
    Remove battery and tray,
    Disconnect coolant hoses from radiator, bottle and heater matrix,
    Disconnect intercooler pipes,
    Disconnect A/C discharge from condenser and suction pipe from compressor (gas will need to be removed first),
    Disconnect A/C high pressure switch wiring,
    Disconnect oil level sensor wiring from sump,
    Remove radiator fans and cowling (slides out of bottom in one go),
    Disconnect fuel supply and return pipes from top of engine,
    Disconnect servo hose join above gear box,
    Disconnect anti roll bar drop links from front struts,
    Remove drivers side lower dash trim,
    Remove drivers foot rest,
    Remove steering column to steering rack bolt (mark first so you get it back in the same place),
    Remove lower wishbone connecting plate (large aluminium plate joining both wishbones) This should drop the whole steering rack and wishbone assembly,

    Now you should be ready to lower the engine! I lowered the gearbox by 3-4 inches onto an axle stand then using a jack under the sump lower the engine by around 6-8 inches keeping on the exhaust, drive shafts and prop shaft,
    Drain enough brake fluid out of the front brakes to empty the master cylinder,
    Remove brake pedal from the servo (Audi have a special tool for this which they won't sell you) I used a screw driver to push the white lugs in through the pedal and pull the pedal away,
    Disconnect brake lines from master cylinder,
    Disconnect wiring from master cylinder,
    Disconnect clutch feed pipe from master cylinder,
    Remove master cylinder,
    Disconnect servo hose,
    Remove servo.

    Reinstall in reverse."

    aqibi2000 likes this.
  6. Gaz78

    Gaz78 Registered User

    Sounds exactly like mine was. Brake servo was leaking slightly. Not enough to affect driving but I didn't want to "risk it".

    So I got it changed. Sadly due to location you can't just simply unbolt the servo and reinstall a new one, due to it being so tight to the engine block, otherwise I would of changed myself.

    I got mine done by Midlands vw who charged £560 including genuine part. If you wanted to buy a cheap servo (circa £120) and change yourself it's alot cheaper. Personally didn't want to skimp on brakes so forked out the money. Very happy with their work though and recommend them

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