Brake Servo Problem at -8 degrees this morning

[pass&golf_tdi]

Hi, This morning it was very cold -8 and shortly after moving for a while, applied the brakes gradually and discovered the brake pedal went very hard as if the servo was not working.

On the rest of the way drove very carefully and deduced that if I applied the brakes several times, the vacuum in the servo was not being replaced quickly enough. Could the very cold temp have any connection with this?

In the summer I did discover the usual blocked drains in the plenum chamber. Could I have some water ingression into the brake servo unit, which is now frozen and that is showing its effect today? Or have I got a tandem pump problem. Any help much appreciated as I don’t want to be driving around with dodgy brakes. Thanks

[kenney]

Hi If you have had water ingression into the servo unit,then i would say it has frozen.Iam afraid there is only one thing to do, and that is replace the unit.

[pass&golf_tdi]

I have been looking at previous posts and I am confident that I do have water in the servo unit, which this morning was frozen and caused stiff brake problem.

Has anyone managed to get VW to pay for this, it's going to cost £465. I spoke to VW customer Support today who were not helpful at all. Apparantly I have to take it to a dealer to get a report form them and just this will cost £48

What a bunch of ***kers:aargh4:

[Crasher]

It is the fault of those people who have been servicing your car, they have not cleaned out your water drain tubes under the battery and under the servo. This water freezing in the servo is one day going to kill or injure someone and then VAG will have to do something about it.

[pass&golf_tdi]

Thanks for the reply. Does the fact the plenum drain clearing was not picked up earlier mean I have no recourse to VW. To me it seems clearly a manufactures design fault. And by the way it scared the brown stuff out of me when I felt the pedal go stiff and the car not slowing down, lucky I was not giving it some welly!

[Crasher]

It is a maintenance issue, not a design fault. Admittedly the drains are small but if maintained correctly, this does not happen, especially on later cars with the full chamber cover.

If VAG don’t do something about this, someone is going to die. I think the fault is in the manufacture of the servo, if it was truly air tight, water would not be sucked in thorough the seems and that is how I think they should address the problem. Changing the design of the drains is near impossible, there simply isn’t enough room and if kept clear, there isn’t an issue anyway. There has already been an Audi recall over this but that is simply to clear the drains, it is not a cure.

[pass&golf_tdi]

Well I am taking it to the dealers tomorrow, so they can carry out the 2007 VAG issued TSB 51B8 to check for blocked drain holes in the plenum chamber.

Although I have already done the above in June when I had a problem with my Siren unit which kept going off and Crasher alerted me to drain hole problem.

I am hoping they will check other components as well which could be affected and when I give them the history, they will take into account that my water in Servo is related to blocked drain hole issue and VW will pick up the tab for that.................well might get lucky if they got some Christmas Spirit........ ;)

[Crasher]

well might get lucky if they got some Christmas Spirit........ ;)http://smileys.smileycentral.com/cat/4/4_1_219.gif

[pass&golf_tdi]

I think I am going to be wasting my time tomorrow too, but lets give VW a chance to do the decent thing.........

If I have to get this done independently, what am I look at for parts & labour?:confused:

[Crasher]

Around £400

[Frank.A]

It is a maintenance issue, not a design fault. Admittedly the drains are small but if maintained correctly, this does not happen, especially on later cars with the full chamber cover.

If VAG don’t do something about this, someone is going to die. I think the fault is in the manufacture of the servo, if it was truly air tight, water would not be sucked in thorough the seems and that is how I think they should address the problem. Changing the design of the drains is near impossible, there simply isn’t enough room and if kept clear, there isn’t an issue anyway. There has already been an Audi recall over this but that is simply to clear the drains, it is not a cure.


The fitting of gravity flap valves in the lower front face of the plenum chamber is all it would take to remove the problem.I have never heard of a C Corsa having any water ingress problems in this area and flaps is how Vauxhall deal with drainage.
Having spent 30+ years in Development Flight Testing I can definitely recognise a design fault.
I enjoy driving the Passat and it tows the caravan well with good economy,but,it is a pigs breakfast in many ares of design.Then again many other manufacturers have problems.
It always amazes me that manufacurers don't learn from their own and others mistakes.What is the point of manufacturers having development centres where they test other makers models for bench marking and then turn out vehicles where form over function triumphs so often.

Rant over,

Best,
Frank

[Crasher]

They are valves but pinch operated not gravity flap which is actually rather a nice idea, maybe you should put that to them? Unfortunately I have seen this a lot, I have a Golf 1 Cabrio here that was suffering the same, the plenum corner drains were blocked with debris and water poured into the car.

[bricam1]

Crasher,

My Passat is a late 54 plate with the full chamber cover on it. Every couple of weeks I check the chamber for water. Is this enough? or I should get the mechanic to check/clear when the car is in for a service?

If this is a maintenance issue do VW dealers check the chambers when the car is in for a service? As do not entirely agree that this is a maintenance issue. In my eyes this is a design fault that they should have rectified by now.

[Crasher]

It is enough to check the drains annually on cars with the full cover and yes it is on the VAG service schedule tick list under the section heading “Engine compartment” and the wording is “Plenum chamber and water drain valve: Check for soiling and clean if necessary” so to me, it is a service issue in that annually checked and cleared drains on cars with the full plenum cover should not become blocked. To be honest, I don’t see how they could rectify the problem as a retro fit, there simply isn’t enough room to make the drains any bigger and removing them isn’t an option due to fume intake from under the car. The idea off a gravity flapper valve may help.

[bricam1]

Just a thought but can the chambers be blocked by rubbish from underneath the car.

[Crasher]

Only if it was about 3 feet deep. :D

[pass&golf_tdi]

Well VW dealers had a look at it and did their tick box checks and confirmed the grommets have been removed.

Tested the brakes and said it was operating normally. Today it was not as cold (-2) and I drove the car for 10 miles and it then stood for 40 min thawing with a warm engine, before being looked at, so may be any ice had melted.

However, based on my previous experience when the servo assistance was limited at -8, they have recomended that I change it £460 thankyou:zx11:

Now it's off with an email to VW customer support manager, arguing my case. Lets wait and see how they respond......................I know, I know there will a lot of, http://smileys.smileycentral.com/cat/4/4_1_219.gif but lets see.............I live in hope.

[pass&golf_tdi]

RESULT - VW came good and have agreed to foot the bill...........and no I am not dreaming :biglaugh:. Now my children will not have to miss out on their Christmas Presents:D

[Crasher]

http://smileys.smileycentral.com/cat/36/36_12_1.gif

[Hex69]

RESULT - VW came good and have agreed to foot the bill...........and no I am not dreaming :biglaugh:. Now my children will not have to miss out on their Christmas Presents:D

Result http://www.loreleiweb.com/smileys/36_1_55%5B1%5D.gif

[Panzerdriver]

RESULT - VW came good and have agreed to foot the bill...........and no I am not dreaming :biglaugh:. Now my children will not have to miss out on their Christmas Presents:D

Top result well done :beerchug: