VW Passat fault - Water in braking system

tania1065

luwpergwin wrote: »

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

hi, we have had a very similar problem with our 2002 1.9tdi, whilst on holiday in europe (we drove) after a heavy downpour had a watery noise from the barking system when pressing brake, researched on internet and found a huge amount of people have issues with the plenum drains being blocked (under battery and brake servo) they become blocked and fill with water leaving battery and servo sitting in water. My husband took battery our and unblocked, the water had managed to get into the servo and cause noise. The next day my husband managed to get car running but smoking form exhaust - he checked oil and sure enough water had mixed with it, albiet with the coolant bottle still full, so the servo is powered by engine and has a vacumn pipe to function, this pipe has allowed water to go in through servo and mix with oil. We took car by tow truck to vw in the next town, after 10 days told me my engine head gasket was gone, they will not admit that water gets into engine via servo. I have phoned my usual garage Highams Park Motor Services :A(who by the way are 100% genuine and I urge you to go there if poss) told me that this actually does happen and to get the car back, change oil and filter and have any remaining water sucked from servo and to change brake fluids to see if this can fix car. VW told me to have a recon engine at cost of nearly 3000gbp, guess who I am writing to about this, this is a recall on some B5 Passats - all VW owners get these plenum chambers unblocked - there is a really usefull site wierd little biscuit who give you photos of each stage of the process - battery rather awkward to get out though.

we will see what happens - trying to get car towed out of vw to a more sensible garage:mad: a spoilt holiday but always make sure you purchase european barakdown - thankfully we did:rotfl:but no hire car for longer than 2 days

keithcolly

I have had the same servo failure in my 51 plate 2.0 passat. Approaching a roundabout could not depress brake pedal. Just like when engine is off and no servo. Lucky no other cars about. Vw main dealer replaced servo f.o.c. Water had corroded servo due to blocked filter. Sounds like it is not uncommon.

VeryUnhapppy_Passat_Owner

Hi, same fault. Brakes kept jamming on but plenum clear of blockage and water. Found servo to be very corroded and jamming brakes on. Changed servo for £290 and all OK.

This is one of many faults found with this car which I have had from new, so 11 years of hassle to date!! 185k miles so far and have spent a lot keeping it on the road. Had an Astra Estate previously for work with similar mileage but nowhere near the same number of problems or cost to keep it going.

Very sorry I believed the 'VW's are very reliable' rubbish!!!! :mad:

Steer73

But your car has done 185k miles??? Any car of that age and mileage will need money spending on it.

climber4791

ESSENTIAL READ IF YOU HAVE A PASSAT 2001-2005
Ive had my passat 4motion for a year, 140k miles. Oh dear, what a shambles purchase.

After some very heavy rain, alarm was going off repeatedly through the evening untill 1130pm which is when I had to go out and disconnect battery. After cancelling internal sensors and just locking the car it was still going off and started going off unlocked. I assumed straight away water had got in somewhere so I started to investigate. Water in passenger foot well? Couldnt feel any? Pulled back footwell carpet, it was wet/very damp. Just because you cant feel wet carpets DONT assume it isnt deep under the carpet and insulation/soundproofing which is about 40mm thick! Next thing, window fuse went pop.

A local garage started to investigate, they said water HAD NOT got in because they too just 'felt' the carpet which was dry to the touch. They took out glove box to see if they could see where the water was getting in the they triggered the airbag light which they couldnt cancel so I just told them to leave it and went to VW specialist, Autotechnik, Blackheath, West Mids.

VW specialist cancelled air bag fault (£36 with the VAT) and then told me to check battery plenum chamber, the steel compartment where battery is located. Straight away I saw it was full of water. I took out the battery and steel plate that battery sits on. Very easy to do yourself. There is a rubber grommit under battery and another one tucked under the round, black steel drum which is the brake servo. Both holes were blocked with black slurry/slim. Water fills up in here and then pours down into the car just under the pollen filter housing which has a very poor rubber gasket/seal which in my opinion is pretty much useless, unless it is clamped right down and seated perfectly in the right position. 3 nuts to take out of the housing and then a bit of wiggling around to free it up, not me the, the housing.

Pollen filter housing is a bit fiddly to get out but I have taken mine out and sealed it with LOTS of silicon sealant. Ive water tested the seal with a hose and not a drop is getting in through there now!! Brakes had always been spongy right from the off and VW specialist said its almost certain you have water in the brake servo or at least quite a bit in the brake lines. A caliper had stuck on some months earlier and garage said brake cylinder on caliper was seized solid with rust and had to hammer it out to free it up. VW specialist also said once you have water in that footwell, dont leave it!! You must take out passenger seat, pull carpets back and get it dried out because that water will stay in there and rot the electrics in a control module that operates several key functions, alarm, windows, door locks.

Car is booked in to have the entire brake system drained and DOT 5 brake fluid put in.

To own one of these cars you need to be a serious VW enthusiast( which I was!!) to maintain them and/or be stupid enough to keep paying out.

Friend of mine has an astra 1.7cdti, with 174k on it. Only ever had to replace the alternator. I had a corsa in my youth which never had water leaks, never broke down and took a right old thrashing. I might be making a return to Vauxhall.

Stooby2

Having read the OP's post which as others have said was very confusing - there's no way water should get into the hydraulic side of the brakes through a breather hose, I then read further down and read the part about servos and plenum chamber and the light dawned. I think what has happened is that the servo has sucked water in through its breather hose, the end of which appears to have become submerged in the filling trough.

That would stop the servo working and it could probably hold several litres. To be honest they should really have replaced the servo as water in there is never a good thing.

I can't see how this would get into the engine oil though. IIRC the vacuum is generated by a pipe leading to the inlet manifold - so any water would go into the combustion chambers and may cause rough running, or if there was a lot of it, might damage the engine through hydraulic lock. It's possible this could wreck a head gasket, but you'd have a hard job proving it - most garages would say
you were unlucky enough to suffer both faults at once.

paddedjohn

Stooby2 wrote: »

Having read the OP's post which as others have said was very confusing - there's no way water should get into the hydraulic side of the brakes through a breather hose, I then read further down and read the part about servos and plenum chamber and the light dawned. I think what has happened is that the servo has sucked water in through its breather hose, the end of which appears to have become submerged in the filling trough.

That would stop the servo working and it could probably hold several litres. To be honest they should really have replaced the servo as water in there is never a good thing.

I can't see how this would get into the engine oil though. IIRC the vacuum is generated by a pipe leading to the inlet manifold - so any water would go into the combustion chambers and may cause rough running, or if there was a lot of it, might damage the engine through hydraulic lock. It's possible this could wreck a head gasket, but you'd have a hard job proving it - most garages would say
you were unlucky enough to suffer both faults at once.

The problem with that theory is that the hose would have to be disconnected at the manifold if it was to suck any water up from the plenum chamber, and for a long time to suck up that much water.

Stooby2

No you're not quite right - there is one pipe that connects to the manifold / vacuum pump that generates the vacuum in the servo. On some makes of servo there is a pipe that has an open end. When the brakes are applied air is drawn in through this pipe as everything moves inside the servo. If you press your brakes with the engine off you can often hear the sharp intake of air as this happens.

It seems in the case, the open end of the pipe has become submerged in water as the blocked trough fills up and has sucked water in.

climber4791

Stooby2 wrote: »

No you're not quite right - there is one pipe that connects to the manifold / vacuum pump that generates the vacuum in the servo. On some makes of servo there is a pipe that has an open end. When the brakes are applied air is drawn in through this pipe as everything moves inside the servo. If you press your brakes with the engine off you can often hear the sharp intake of air as this happens.

It seems in the case, the open end of the pipe has become submerged in water as the blocked trough fills up and has sucked water in.

Having spoke to the VW specialist autotechnik this morning they are advising me to replace the servo. Its going in on Friday 12th Oct 2012. Will let you know what they say and ask them about the chances of water being sucked into the engine by the servo vaccum system.

Stooby2

Been reading up on this as it's quite interesting, seems to be a fairly common fault with the Passat. It's either sucking air in via this breather hose or water is running down from the trough over the brake rod (from the pedal) into the footwell and on the way drawn into the servo through the vent there.

Good advice to replace the servo.