Hard Brake pedal? Dangerous! AA couldnt find the problem Please Help!

[pasta]

Hello,

My brake pedal on my Audi A4 Avant 130 1.9 tdi 02 plate suddenly goes hard as a rock and braking is practically non existent!
Called the AA out they done the usual checks ie peeked for leaks, engine off pumped pedal engine on checking for a drop on the pedal, all seemed to be working fine, test drove it for 20 mins various breaking conditions nothing all back to normal so given all clear. On way home this morning on motorway it happened again vary scary!
Any ideas before I get it towed to a specialist? As would like to get an idea of cost before it disappears.

Regards and Thankyou for any help!

[zollaf]

have a look in the plenum chamber, the void that the battery and servo sit in. is it full of water ? if not, put a hose in it and see if it drains or fills up .

[pasta]

Apparently it was before MOT 2 months ago a bung thing was pushed through to release the water as it was not draining away and the bung isn't really needed?

[zollaf]

therefore the servo may have had water inside it that can cause this exact problem especially when it freezes.

[pasta]

OK that would make sense in our current climate! So can this usually be fixed easily or is it a new servo? Thankyou for all your help!

[zollaf]

new servo is the safest way to go.
i presume when this happens you push the pedal and it is literally 'rock' solid and there are no brakes, not just very hard with some brakes, same as it is if you pump the pedal a few times to exhaust the vacuum with the engine off.

[pasta]

Yes exactly!

[mumutley]

I agree with zollaf

replace servo, and get the brake vacum pump chcked

[zollaf]

the servos probably has a porous seem so should really be replaced then. i think you have taken a wise move to get it recovered. now, since the plenum has flooded you should check under the passenger carpet as this may well be soaking wet and can cause more expensive problems if the electrics under there stop working. also check the pollen filter.

[pasta]

Right heres the latest!
Brought a new servo from Euro car parts as GSF couldn't get one and suggested getting one from Audi direct, checked out the price done a bit of home work on the item and Euro car parts it was. £240

Got it fitted and got a phone call from the garage telling me it was a right pain to change and that it was full water and completely knackered! £120.

So from the advice and help from you guys a big thank you!
Problem Solved!

[neil1052]

Hello,

My brake pedal on my Audi A4 Avant 130 1.9 tdi 02 plate suddenly goes hard as a rock and braking is practically non existent!
Called the AA out they done the usual checks ie peeked for leaks, engine off pumped pedal engine on checking for a drop on the pedal, all seemed to be working fine, test drove it for 20 mins various breaking conditions nothing all back to normal so given all clear. On way home this morning on motorway it happened again vary scary!
Any ideas before I get it towed to a specialist? As would like to get an idea of cost before it disappears.

Regards and Thankyou for any help!



I've had a similar intermittent problem on my 2002 VW Passat 1.9 TDI Sport AVF Engine, which I'd diagnosed as a loss of vacuum, so after replacing all the old vacuum hoses was disturbed to find my local MOT tester had picked up a loss of Servo assistance so i'd not had any scary moments as discribed above :mad:

I inspected the whole system & found the Vacuum Pump (on the end of the cam) had a pressed in hose connector which appears to have fretted & become loose !
Several coats of araldite around the offfending connector on the pump has sorted the problem, & the vacuum has returned !
I will be digging deep for an upgraded vac pump which has a screw in connetor instead of the original push in connector.
I also found a youtube video online which describes the problem !
Kruciec, pompa vacum 1.9 tdi vw passat b5 3bg 2002 - YouTube (http://www.youtube.com/watch?v=ZoB4U5PmnrU)