On two occasions I have had the brakes fail when joining a roundabout. The brake pedal goes hard like the servo is not working and the car does not stop, quite frightening. Problem goes away and works perfectly ok when you go for the brakes again.
I googled this problem and found that it is a common problem with the A4, RAC website has at least 20 members that have had the same problem!
Have taken the car to Audi today and they have confirmed water has entered the servo and master cylinder, cost to replace £780 including 10% discount!
The water gets into the servo via the plenium chamber (battery area). This surface water is meant to drain away via a 'plug hole' located under the battery. As this plug hole is impossible to access without taking the battery out and the fact you would not be aware of its existence, it gets blocked and therefore causes the problem.
I now learn that this plug has been the subject of a recall notice for this car of which I have never been made aware of. They say they made the modification in August (2009) when cam belt changed. No notice of that when picked up in August and no mention of it on invoice when paying cam belt bill. So I am left to think that they never did this modification, hence the water ingress.
So left high and dry, with a known fault about water ingress to servo causing sudden loss of brakes.
I have owned the car from new at the same address. Audi managed to send me sales details but don't manage to call me in for what I consider to be an important recall.
I would be glad if any other A4 drivers have had any similar problem and ask if you could post here if you have had the 'drain plug' modification done and whether you know about it. For something as important as brakes, I feel I am not going to be fobbed off quite so calmly, without a fight.
Edited by Webmaster on 06/01/2010 at 20:02
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I have a 2002 A4. In the recent past it has been serviced by an independent but in Nov I took it to Audi for its MoT to take advantage of their free MoT offer. They did MoT and told me they had also done the plenum chamber mod. (Does anyone know what this modification consists of)?
I am a little surprised you have not become aware of the problem. When holes are blocked you get a water swishing sound when you go round a corner.
Having removed the battery a couple of times I eventually "solved" the problem by pushing a piece of stiff wire through the hole under the servo, leaving the wire in place and periodically jiggling it to release any water.
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Water in plenum is a well know problem in a few VAG group cars. However i believe you only get a postal recall notice if it is a official VOSA recall for your model of car. Get then to confirm any work carried out in writing and go from that.
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www.vwaudiforum.co.uk A4 forum. Regards Peter
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We have a 2002 (51 plate A4 1.9TDI) bought from Lincoln Audi 5 years ago, brilliant car, wife uses it for work and hasn't give any problems until Nov 2009 when the brakes failed whilst the wife had the kids in it, symptom was that the pedal went hard and she struggled to get the car to stop, AA called and they said that the vacuum pump had failed, AA recovered the car to home address and I purchased a vacuum pump and had it fitted. That seemed to solve the problem for about 300 miles when during the week before Christmas and during the really cold weather the brakes failed again! They wouldn't work straight off the front drive but after I had left the car running for 10 minutes they worked fine. Whilst taking the car to our local garage the brakes failed on me! I'm used to cars without servo assistance and stopped the car without much trouble but can understand the fright my wife got back in November! The garage checked every pipe and bracket and came up with the assumption that the servo was knackered! Unusual they say for an Audi, they did point me in the direction of the internet and the servo problem! I was appalled to see the brake failure is a common problem and is simply down to this drain plug under the servo! Had the battery out and found about 1" of water in the chamber, a tide mark in the chamber suggests it has been higher. Have now stuck a screwdriver through the drain and all the water has drained off. It got high enough to immerse the bottom of the servo and has no doubt got in there! I have tried the brakes since and they appear to function okay however the wife has lost all confidence in the car and no doubt I will have to replace the servo. I am reluctant to take it to Lincoln Audi as they have our details but have never made any contact with us about this fault and recall! If they had have done I would have kept an eye on the drain and made sure it remained free.
Interestingly the wife reported that prior to the AA call out she thought there was a problem with the brakes as she went round a local traffic island during a period of heavy rain but thought she had imagined it - bless her! No doubt the brake servo had got a good soaking as the water sloshed around
The Audi is a well built quality car, at the recent MOT test the examiner allowed me to look around the underneath of the car and its build quality is top notch. I am at a loss as to the attitude of Audi to this common problem, what an appalling public relations exercise! A new Servo costs £230, a typical Audi garage bill for the repair seems to cost between £600 - £800 I think they should be willing to do the repair at cost as a good will exercise!
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Hi Tommo
That's about the sum of it.
Looks like exactly the same problem I am having at this moment in time.
Car is with Audi at the moment, I have written to Audi customer Car and the Audi Garage, pointing out this common failure, both have not responded in any way. It seems they will not be drawn into any form of written correspondence as it may prejudice any subsequent claim.
It has really annoyed me this time round for some reason, as the first thing I am presented with in the glossy showroom when booking car in for repair, was the Service Advisor's personal business card, clearly showing his email address that you may 'correspond' with him on.
I never seem to learn, I should not be so surprised, when, eventually I will be presented with this bill, that I will just get that same smug look, not giving a toss, whatever atitude.
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I contacted Audi about the servo problem last week, I had heard that the cause of the servo failure was a grommet located in the bulk head, the brake hose goes through this, it grabs the hose and when you call for a second servo assist on the brakes it kinks through the grommet causing the servo assist to fail. Neal a technician at Lincoln Audi said that he had heard of this but no they are not doing a recall! He asked for the car's full chassis number as they only had a part number on their records, he then told me that the car had been subject of a campaign recall on the plenum chamber in 2007 but because I had taken the car out of Audi service in 2006 (what's the point paying premium prices to keep a full Audi service record once a car is at a certain age) it had been missed. I told him that I knew what the fix was, a screwdriver through the drain to clear it, Neal said they went further and removed the bung as well, so no chance of the chamber filling up again! This is the staggering part - Audi are paying to replace the servo under warranty - a 8 year old car - still covered by warranty work!
Perhaps the good people at Audi have bowed to pressure!!
Going in Weds this week for the work to be done - hope it is the servo now!!
Very helpful at Audi Lincoln, still cant believe it
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Have got the A4 booked into our local garage for a servo replacement, would you believe it VW parts UK can't supply the part until 29/1/2010 - its on back order because of the high demand!! The garage tell me that they have another servo to replace on an A3 -same symptoms as our car
so we are without the car until Feb!
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Dealers and others refer to the modification when all they do is remove the duck bill rubber water drain. The reason for the duck bill is to stop air/engine fumes entering the plenum chamber which is the source of air for the pollen filter. The bungs can easily be removed, cleaned and replaced and are accessible from underneath. Why Audi do not include this as standard annual practice I do not know.
If you wash you own car flood the windscreen and ensure you can see water falling from the rear end on the gearbox. Regards Peter
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Thanks Peter D
That has been the first proper explanation of this problem internal recall. I guess my problem started with this cold snap. Water must have frozen the drain outlet with or without this drain plug modification. As my drive at this time of year does not get any sun, it was not helping the defrosting process, compounding the problem.
To conclude my sorry experience, paid bill of £795 with gritted teeth, and yes, that same blank, couldn't give a toss look was on the Service Adviser's face!
Oh and one more thing, when the Service Adviser tells you he has spoken to and asked Audi Customer Care on your behalf for a goodwill payment or a favourable contribution, he is lying. On further questioning him, it turns out that he did not speak with them at all, all he manages to do, is talk with his Manager who has the 'Audi authority' to yeh or ney your request. Something to be aware of, if you are perhaps trying to resolve disputes between you and the Garage.
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A fairly typical VAG response to their own bad design. Even though this fault is dangerous, they couldn't give a toss. Worse still, they produced newer variants of this model (Skoda Superb) with exactly the same fault - crass behaviour. Vote with your cheque book next time.
As far as these bungs are "easily accessible from underneath", I would beg to differ, especially in the case of the later diesels where the heatshielding around the turbocharger and other components gets in the way. The duckbill design is stupid. It clogs with decomposing biomass in the Summer, then sticks shut. In Winter, the plenum chamber "pond" fills up, rusts the servo which ingests water and causes brake failure when frozen. Brilliant.
Take these bungs right out - battery tray removal is necessary on the LHS and a pipe runs through the servo side drain - and check the pollen filter housing seal for foam degradation. A modified seal is available from VAG.
If your vehicle has a properly functional exhaust system, the chances of fume ingress due to bung removal are almost zero. Most sensibly designed vehicles don't have bungs here at all. When the vehicle is in motion, the plenum chamber is pressurised by ram air anyway.
659.
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<< When the vehicle is in motion the plenum chamber is pressurised by ram airanyway.
Spot on 659, as you say, air flow should have caused a positive pressure in the plenum and forced the water out.
It does seem strange that some expensive electrics (fan and movable air duct flaps located under pollen filter) are situated in this chamber, that we now know are prone to quite a lot of water sloshing around.
Just a final laugh, the receptionist, who was on remote control duty doing her standard follow up call asked 'Just a courtesy call Sir, were you happy with the service received from Audi.......!!!!!!!!
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I take it this doesn't apply to B7 A4's ?? Only B6
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Lincoln Audi have confirmed that they are replacing servo, master cylinder and associated pipework free of charge because of water damage by the blocking of the plenum chamber drain!
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tommo, have they repaired your car free of charge, other A4 owners I'm sure would be interested to know.
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Tommo
Would you believe it, having had the servo and master cylinder replaced 11th Jan, yesterday I had the same horrifying brake loss coming off the motorway, stiff brake pedal.
I went straight back to Audi today, they were very reluctant to see me, but eventually they took the car in for inspection. I was phoned three hours later, and guess what, they tell me that the vacuum hose passing through the bulkhead grommet deforms,this grommet distorts under heat from the engine bay, which in turn crimps this vacuum hose, causing the hard brake pedal.
Having missed your earlier post regarding this grommet, it looks like I am starting to build a better picture as to what the hell is going on. Having paid the £780 for the servo etc. I would like to think that the real bill should have been just for a rubber grommet. I live in hope!
Can we name and shame on this site, my home is near Chandlers Ford, near Southampton, which may or may not be of interest.
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This is yet another example of an inadequate testing of a conversion to RHD.
VAG designs seem to be particularly prone to this - I suspect they just can't be bothered given the small number of units involved.
On a LHD car the servo is on the other side and the run of the vac pipe to it is much more favourable. I particularly dislike the tight "pig's tail" detail where the pipe enters the plenum chamber with an over-tight turn to accomodate engine movement. Coupled with the rather hard plastic they have specified for this pipe, I would anticipate kinking, frettage or failure under cold conditions (we have just been through a winter).
I'll have a very careful look at this detail on my Skoda Superb.
VAG seem to have no qualms whatever about transferring dangerous defects to new clones of an existing model. This and rainwater ingress are good examples.
Shame on them. I have more respect for Toyota.
659.
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The problem occurred in the USA too with LHD, but was soon nipped in the bud with a recall years ago. While we were all told it was the first time they had heard of it, and VOSA said they were happy with VAG procedure of clearing the drains at service time.
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' VOSA said they were happy with VAG procedure of clearing the drains at service time. '
That's fine for the 50% of cars that were serviced by VW.
But not so fine fore the remaining owners who knew nothing of the potentially very dangerous brake failure that could occur. ( I speak from experience here )
I do not understand VOSA's reasoning for not initiating a recall.
Or is there now so much comercial pressure from manufacturers that VOSA get frightened into submission.
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More sites reporting same old problem with water ingress. Is it worth trying to get Audi to pay their customers back retrospectively for expensive Servo replacements.
www.audi-sport.net/vb/a4-a4-cabriolet-s4-forum-b6-chassis/107241-plenum-chamber-drain-grommets-every-a4-b6-owner-affected-common-fault.html
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hello we have an audi a4 and our servo went on it we have sorted some aftermarket and they are only £145 + vat
many thanks glaze auto parts
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