VW Passat fault - Water in braking system

luwpergwin

Sorry if this is in the wrong place but I’m a bit new here.

I recently had a problem with my 51 plate VW Passat. I went to brake at a junction and the brake pedal didn’t move. I was lucky that nothing was coming as I overshot the junction and had to swerve across both lanes.:eek:

I pressed them again and they seemed fine. The next day I took it to a local garage and explained the problem. I had another minor problem anyway which was when ever it rained the foot well become soaking wet. I asked them to check that while they had it in. When I called back they told me that they had drained 3-4 litres of water out of the brake system??? What had happened was this. There is a trough under the bonnet against the bulkhead about the width of the car. It catches the rainwater from the windscreen and allows it to flow out of the bottom of the trough.

Now the brake system overflow pipe also runs into this trough. In time the water exit from the bottom of the trough had become blocked with leaves and dirt. This had caused the trough to fill up with water till it overflowed. This would explain why the carpet was getting wet when it rained. The brake fluid overflow pipe had become submerged causing rainwater to flow into the system. As the water was heavier than the fluid it sank into the system and caused a siphon effect. Brake fluid out, water in.

He cleaned the blocked exit and replaced the fluid. Things were fine until a few days later the brakes started sticking on. This was the opposite to the initial brake problem.
I had to pull the pedal back up with my foot to drive away this time. I took the car into a dealer as it was not drivable.

The VW dealer told me that the servo-system needed replacing as it had gone. He then gave me the price. Almost £500 in total.:mad: It was a VW only part and I was really stuck for transport so I had to bite the bullet.

I’m pretty sure that the water damaged the servo in the first place and view this as a design fault. I’m seriously thinking about sending them a letter and asking for some offset against this £500 bill. Also this might cause a fatal accident one day so it needs addressing. What approach do you think I should I take and where should I write to? Are there any safety watchdogs I can contact?

All comments appreciated.

Many Thanks

kennyboy66_2

I don't know much about cars but do know that water ingress is a fairly common problem with both passats and Audis, and I have experienced this with 2 different Audi A4's (N plate & V plate) - the main dealship asked me accusingly if I parked under a tree! I have not heard that this could cause brake problems though.
See the forum vwaudiforum.co.uk and try asking if it is possible that this could have caused the brake problem.

ps VW parts are horribly expensive.

SaraSeahorse

I had a similar problem with water under bonnet channel with ford galaxy - in my case though it flooded and corroded electrical fuse / relay box under front passenger seat ( causing fault with central locking which then stopped working but car woudl lock and unlock itself and electric windows would open by themselves)

with time the drainage channels had become blocked with leaves. sludge and silt

this was down to my lack of knowledge and clearing the channels is down to the owner maintaining the vehicle correctly

I do see your point about it being bad design but it is down to owners to maintain the vehicle

moonrakerz

luwpergwin wrote: »

When I called back they told me that they had drained 3-4 litres of water out of the brake system???

Firstly I would suggest you go to a garage that knows what it is talking about !. NO car braking system holds 3-4 litres of anything. I should imagine the average car holds about a litre.

luwpergwin wrote: »

Now the brake system overflow pipe also runs into this trough.

Never heard of "the brake system overflow pipe" ! There is a brake fluid reservoir and this is sealed - to stop water and dirt getting into the brake fluid. The last thing you would want on a car is brake fluid overflowing. It is extremely corrosive and can be highly inflammable.

You may well have a problem with your brakes caused by water. Brake fluid is "hygroscopic" - which means that it absorbs water. This is why you must change your brake fluid every 3 years or so and must always use a new sealed container of fluid. If you get a lot of water in the brake fluid you will get major - and potentially dangerous - problems with your braking system.

But some of what you have been told is rubbish of the first magnitude !

Searcher

moonrakerz wrote: »

Firstly I would suggest you go to a garage that knows what it is talking about !. NO car braking system holds 3-4 litres of anything. I should imagine the average car holds about a litre.



Never heard of "the brake system overflow pipe" ! There is a brake fluid reservoir and this is sealed - to stop water and dirt getting into the brake fluid. The last thing you would want on a car is brake fluid overflowing. It is extremely corrosive and can be highly inflammable.

You may well have a problem with your brakes caused by water. Brake fluid is "hygroscopic" - which means that it absorbs water. This is why you must change your brake fluid every 3 years or so and must always use a new sealed container of fluid. If you get a lot of water in the brake fluid you will get major - and potentially dangerous - problems with your braking system.

But some of what you have been told is rubbish of the first magnitude !

I was beginning to wonder how water got in there myself especially in such a large volume.
The mechanic you took the car to either knows nothing at all about braking systems or is a con merchant of biblical proportions.

The braking system is totally sealed, it has to be for it to work the way it does. If you introduce a leak into the system or a mean for the fluid to escape then it just doesn't work and pressing the pedal doesn't produce the pressure needed to operate the brake cylinders.

I'm more inclined to think that the problem was more to do with the failing servo than "water in the system"

luwpergwin

moonrakerz wrote: »

Firstly I would suggest you go to a garage that knows what it is talking about !. NO car braking system holds 3-4 litres of anything. I should imagine the average car holds about a litre.

I think he was saying that it was pulling water through the system from the trough as he drained it. Im going to look into the technical side of it. He had no reason to BS me. What you pointed out does make sense though. The whole system works under pressure and should be sealed.

Hmmm... I'll get to the bottom of it and I'll be back.

gibby

was this a main dealer by any chance???

as the car is a 51 its well past the warranty but try a smaller garage that is good to a friend.

we had a water problem with an old escort hitting the battery
my mother took it to a main for dealer & wanted £500 to fix it
but my local garage did it for £50

also main dealer parts can be really expensive and alternatives of good quality are usually just as good.

Im surprised at VW though as they are usully very good
I wouldnt have though a 51 passat would ahve such problems

G

mrtg0525

luwpergwin wrote: »

I think he was saying that it was pulling water through the system from the trough as he drained it. Im going to look into the technical side of it. He had no reason to BS me. What you pointed out does make sense though. The whole system works under pressure and should be sealed.

The system only works under pressure from the master cylinder (pump) downwards - there is no pressure in the brake fluid container on top of it.

The bit about water sinking to the bottom doesn't make sense to me, though. Brake fluid (with the exception of DOT 5 silicone fluid) is hygroscopic so it'll absorb water. The problem with that is that it lowers the boiling point of the brake fluid, which can lead to steam bubbles occuring in the system under heavy braking, but it won't "replace" the fluid.

Unfortunately excess moisture in brake fluid can lead to internal corrosion and to the brakes sticking on, depending on where the corrosion occurs.

That said, most modern cars have drains in front of the windscreen that need to be kept clear. A lot of people don't but that doesn't mean it's a design fault...

tomstickland

I'm a bit confused as to how water was making its way into the braking system.

Re brakes sticking on, this does sound like a servo problem. I drove about for a month or two having to use my foot to pull the brake pedal off a few years ago, all caused by a distorted servo.

You should source the servo from a scrapped car and have a back street garage fit it if you want to cut the cost down from £500.

mackay78

I know this is an old thread... but given the weather conditions there might be a few people (like me) googling this.

So I had these symptoms: brake jammed a bit... then worked then jammed (as in, it wouldn't go down). A few hours later, tested it and it was fine. Then the next morning was about to start a motorway journey... brakes worked again and then, when pulling out of a car-park they jammed again (wouldn't go down).

Garage quoted £500 total for it (£300 for the part from an official dealer) plus 4 hours labour time. I hunted around online and found a few alternatives. Got a brand new one for £195 so about £100 saved (still had to pay labour) - only difference was it wasn't in an official dealers box!

PW Europarts.
http://stores.shop.ebay.co.uk/P-W-EuropartsLTD__W0QQ_armrsZ1
01384 565300

Re. the original fault... I've had about 4 or 5 people say the same thing... the brake servo does have a problem where leaves clog up drainage pipes, water gets in to the servo system, water freezes and then kills it (if you're driving while it's frozen). Usually when it rains, it will drain out again later... but if it clogs, rains and then freezes, you're in trouble. It's only a problem in freezing weather conditions. Ask your garage to show you how to check it's not clogged up if the weather gets cold and save yourself £400!!

missile

moonrakerz wrote: »

But some of what you have been told is rubbish of the first magnitude !

I think OP may have missunderstood the mechanic?

Brake fluid is hygroscopic i.e. it absorbs water. It is recommended that you replace the fluid every two years. On a 51 plate car I would guess it has not been replaced for ............ a while

It is false ecconomy to penny pinch on maintenance and I would suggest that is the cause of the brake problem and failure of the servo:cool: