Passat brake problem

[wkholi]

Hi all
when I hit the brakes all the way on my Passat 2008 automatic , the brakes just do not release !! I have to park aside and keep on hitting the brakes again a few times or stop the engine and wait for a while and the turn the engine again till the brakes release . My mechanic suspected the ABS unit , so we installed another reconditioned ABS unit but still,the same problem . He connected rather vag computer to the car and checked the car sensors and all seemed to be fine as they all read the same readinfpg , we checked the parking switch but it is working properly ! Actually he ran of ideas and he wants to change another ABS as he doughnuts that this ABS is faulty too !! PLEEEEEZ help if anyone have any ideas . I have been on the net for 4 days looking for a similar problem but I did not find a solution yet .

[Col]

Vacuum servo sticking?

[wkholi]

Vacuum servo sticking?

how to check if the vacuum servo is stickingb?

[zollaf]

first off, you need the car on a ramp. you then get the brakes to lock. you then undo a brake connection . first off at the caliper, then you work back towards the abs pump. if you undo the union at the caliper and te brakes suddenly release on that wheel, its a caliper. if they don't, its the slider or pads seized. then get them to lock again and do the union past the flexi hose. if that makes them relese, its the flexi. basically, you undo the union to release the pressure. if you have t release the master cylinder unions to get it to release, then its the mc. etc.... basic mechanics that your mechanic should know about tracing a fault, rather than charging you to replace perfectly good components.

[wkholi]

My mechanic took the servo vacuum off and that should release the brakes if the problem is with the servo , but the 4 wheels are still sticking !! i guess that tkes the servo option out . Any other ideas . we have been in this issue for 5 days !! and no luck yet !

[wkholi]

My mechanic removed the two rear motors of the brakes and he tried again , same thing when the brake is pressed all the way the front wheels got stuck !! Any other idea please .

[zollaf]

a servo can't lock the wheels on. all it does is to help the pedal be softer, unless its full of water which is an option. could be the master cylinder then. they can stick.

[wkholi]

We Changed the master Cylinder , as the car had two problems first , 1- the brake pedal was low , and when we changed the master it became normal as it should be . 2- When i press the brakes all the way down , i feel the vibration of the brakes pedal ( i guess that means that the ABS is in action ) then the brakes would not retract back ! . This second issue my mechanic have been diagnosing it for 5 days and no luck yet .