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coup80
13-01-2011, 02:44 PM
Hi i hope someone can help me,over the last few days when my girlfriend has taken the car to work a4 avant 1.9tdi shes phoned me up in a panic saying the first time in morning she puts brakes on theres just a hard pedal and no braking action,however if she releases padal and reaplies they work fine and continue to work fine for rest of journey just seems to be once car has sat all nite or all day,any help would be apreciated as every time i check it it seems fine,and i know the garage will prob say the same:1zhelp:

nevo
13-01-2011, 03:45 PM
Sounds like you're losing servo vac overnight,try pressing the pedal before starting the engine,there should be still a vac left in the servo,enough to press the padal down,You need to sort that out pronto otherwise she'll be hitting something,ever tried braking without the servo it requires a lot of force!try looking for leaks non return valve maybe.

coup80
13-01-2011, 05:22 PM
hi think you might be right i just drive car and it did it to me aswell twice so its getting worse,

5up3rman
15-01-2011, 12:11 AM
thats 99% gonna be a servo problem.
that needs to be sorted out ASAP
do a search for plenum chamber and servo and you'll see it's a well known problem
Thankfully i've never heard of a very serious accident because of it, but please dont be the first.
get it sorted asap

rhencullen1989
15-01-2011, 12:50 AM
I reckon your plenum chamber drain holes have been blocked and during heavy rain the plenum chamber has filled with water and killed your servo. You may have to fit a new servo and remove one or both of the drain grommets. One under battery, and one under servo.

5up3rman
15-01-2011, 12:57 AM
agreed get them to justtake out the grommets when they replace your servo.
make sure every 6months you clean it out.

coup80
15-01-2011, 08:56 AM
ive seen a few threads on here saying this was a audi recall for the bungs blocking and leading to break failure,do you think audi would fix this under this recall if its related.if not wot sort of money is in a new servo,thats got to be expensive.

nevo
15-01-2011, 10:05 AM
You can check if the plenum chamber is blocked just lift the battery cover and check around,having said that these servos have a habit of rusting internally could of been a previous owner,anyway you can go down to audi give them your VIN number see what they say,but it may be down to having full service history?many years ago my wife wrote off my audi 100,lost servo assistance,managed to slow it down to walking speed then hit a lampost!

coup80
15-01-2011, 11:06 AM
Hi i just checked brake fluid and around the top of the reservoir looks wet to me as if fluids been leaking out,once opening cap i found reservoir is full to brim you could not fit another drip in,in my opinion it should not be like this,i phoned audi this morning and they told me mine wasnt affected with the plenum chamber its a a4 2003 tdi,could there be water getting in reservoir,or could it be a simple break in vac hose between engine and bulkhead? iam scared to drive it,booked into garage tomorrow but as its a intermittant fault iam sure they will tell me servos fine and try and get me to get new discs and pads aswell althought they are slightly worn these are definatley not the source of no brakes and a solid pedal almost asive i have a bit of wood jammed uder pedal and cant push it down,

nevo
15-01-2011, 01:27 PM
You are right to take it in for assessment its definitely the servo or master cylinder area, average wear on the pads and discs will not cause this,ask them to take off the vacuum pipe off the servo and see what the condition is,also check the condition of the pipe for internal collapsing,the master cylinder overfilling might be just that overfilling.when there's no vac in the servo its just like you said,a block of wood under the pedal.

coup80
15-01-2011, 08:39 PM
how will i know if it is the servo or the master cylinder?

thanks

nevo
16-01-2011, 10:14 AM
My money's on the servo,m/c,would be spongy and let air in,if you,ve got a hard pedal,it looks ok.How long have you owned it?have you been topping it up?

coup80
16-01-2011, 11:34 AM
Hi ive had car for about 4 months and have not topped up fluid atall,the strange thing is car has been fine since,very strange

nevo
16-01-2011, 02:42 PM
The reason I asked is theres a possibility the M/Cis weeping fluid into the servo,hence the full to the brim reservoir by the previous owner,just something else for your mechanic to check

rocker55
17-02-2011, 08:53 PM
I also had a recall letter in August 2010 and didn't bother with it as I had removed the bungs in 2006 not long after I bought the car.

Yesterday the brake pedal went hard and I nearly ******* myself into a roundabout. luckily no-one was coming and I managed to drive round it, although more at speeds I haven't done through a roundabout in almost 20 years.

I called Audi and told them about the brakes and that I had read about the recall on here (I never mentioned my letter, was pleading ignorant)

Anyway, I took it in today not really holding out much hope and was happy to return an hour later to find a printout detailing worn drop links, 90% brake disc wear (they are only 2 1/2 years old) and a buggered servo.

the good news....They told me the car was too dangerous to drive and that they would repair the servo and check the brakes under the recall warranty...FREE OF CHARGE...I couldn't believe my ears

The printout had £832 for all the parts listed above, this is without labour, but I am just getting the free warranty work done, will get the other stuff done elsewhere.

I am happy to be an Audi driver once again.

Picking the car up tomorrow, hopefully back to its best again.

1 point I forgot, whilst driving with the said knackered servo, the car went into limp home mode. Couldn't get over 50 mph all the way to work and home. I was told this was nothing to do with the servo by.....wait for it....the receptionist....hahahaha.

Surely it has to be linked...This morning the barkes worked fine and my engine was running as normal as well, on my way to the garage..typicall eh?

Do me a favour love...2 sugars and milk please, leave the diagnostics to the tecchies...

Sorry, I'll probably get sacked for that last comment.