Here's what's driving me mad:

One of the front hoses was frayed and had to be changed. Brakes worked perfectly until then. Hose was changed brakes bled and now have the pedal travelling/sinking to the floor.

The mechanic bled the master cylinder and the brake pedal got to correct setting: no more travel.

But when the brake is used once all the wheels lock and will not release. Open a bleed nipple and they all will release until the brakes are used again. Seems that the front ones are more on than the rear.

any ideas? Got a new master cylinder to put on.

Air in the abs block?

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I was thinking that the master cylinder wasn't letting back fluid. The brakes all free up if I open a bleed nipple at a wheel. Disconnected the servo and the same issue still remains.

How do I check if there is air in the abs block?

Thanks

You need VCDS or similar to bleed the pump.

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Small update:

 

Fitted the new master cylinder and the issue has improved immensely but still grabbing a little intermittently. Think more so at the rear: car failed test on handbrake imbalance 68% but was at 14% before.

 

Power bled the brakes, but never got a chance to manually engage the ABS to activate the pump. Does this work? Slam on the brakes when driving to activate the pump?

Small update:

Fitted the new master cylinder and the issue has improved immensely but still grabbing a little intermittently. Think more so at the rear: car failed test on handbrake imbalance 68% but was at 14% before.

Power bled the brakes, but never got a chance to manually engage the ABS to activate the pump. Does this work? Slam on the brakes when driving to activate the pump?

You can only bleed the abs pump with VCDS or the dealer computer, not any other way.

Has the system been drained or has air got into it during the work so far?

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FYI

2006 MkII 1.9 PD105 L&K with Ate master cylinder does NOT have a bleed nipple, other types may have or perhaps that was only on the MkI as there is no mention of it in the Haynes manual.

I have heard of activating the ABS on a slippery surface e.g. grass/gravel then bleeding the brakes but the hassle for an uncertain outcome means a garage with plugin unit is easiest to purge the system.

A simple 10 minute job on the ramps.

Edited 11 March, 201610 yr by MicMac

Hi

 

Still haven't gotten to the bottom of this issue. The master cylinder (think there was two bleed nipples on it)  was power bled at the same time as the brakes.

 

With the servo disconnected the same issue occurs

 

Can I give one more symptom the mechanic jacked up the car did not touch the brake pedal and with the wheel off the ground started up the engine and that wheel began to bind: brake pedal never stepped on!

 

Does this defo point to air in abs system? or something else? The pedal doesn't seem to get over hard works as normal, servo seems to work correctly (as in you can feel the servo engage and pedal doesn't go to the ground either)