Yeti SE brake problem at 3,800 miles

[K100RS]

Yeti SE 2.0 litre diesel

We are very happy with our Yeti 2.0 litre diesel which returned 54 mpg over some 1,500 miles travelling abroad to Germany, Belgium and Luxemburg with no problems fully laden.

On returning back to the UK I noticed if you keep an even pressure on the footbrake the pedal continues to slowly go all the way down to the bottom?

On all my motorbikes the hydraulic pressure is solid at the brake lever as it is a fluid and on our other cars the footbrake stops moving once a constant pressure is applied unless of course air has got in.

Our Yeti has covered only 3,800miles so far so could anybody tell me if this is a feature with the Yeti or should the brake pedal stop once the pressure is applied?

I have only come across this problem with an old car when the master cylinder seal has started to leak allowing fluid to pass by the cylinder.

Thanks in advance for any help as I do not want to drive to the local dealer in Norwich only to be told there is no problem with the Yeti brakes.

[The Plumber]

Doesn't sound right to me, have you checked the reservoir contents and looked for signs of leaks :wonder: around the master cylinder/servo and ABS pump on the other side, also for any damage to the flexi pipes to the callipers. Could also be a vacuum problem, had that on a Favorit; could hear a faint hissing from the sevo with the bonnet up :S

Hope you get to the bottom of it,

Regards,

TP

[The Plumber]

Just been having a look through through Elsawin and found the following brake servo test;

Functional test:

With the engine off press down brake pedal repeatedly with force (this reduces the pressure already present in the device).

Now hold the brake pedal in brake position using a medium foot pressure and start the engine. If the brake servo unit operates perfectly the brake pedal must yield noticeably under your foot (servo boost takes effect).

if there are faults replace completely

To test the master cylinder requires tools so a dealer job

TP

[Bigfoot]

My brake pedal does the same (slowly goes all the way to the floor under continuous foot pressure). My wifes previous car, a Honda Civic did the same as did my previous car, a Renault Laguna. It really concerned me when my Laguna did it and after much discussion with the local Renault garage and Renault UK, I was assured it was supposed to do this as it is the way the ABS brakes are set up. As my Yeti does it I have assumed (rightly or wrongly) that this is normal. As long as the brakes work as they should and stop the car then all should be OK. But it is disconcerting when you first first realise what's happening. On all my earlier cars the brake pedal has locked up solidly under pressure which makes you think something is wrong with the newer models. If anyone can say if this is as it should be it will be Johann (900000). He's a mine of useful information.

Edited 18 September, 2011 by Bigfoot

[kenfowler3966]

Not tried it in the Yeti, but my previous superb did this from new for the entire 70k miles I did in it. It was never an issue in normal use, and only sank under a very firm pressure, perhaps there is a pressure limiter in the system somewhre

[K100RS]

My brake pedal does the same (slowly goes all the way to the floor under continuous foot pressure). My wifes previous car, a Honda Civic did the same as did my previous car, a Renault Laguna. It really concerned me when my Laguna did it and after much discussion with the local Renault garage and Renault UK, I was assured it was supposed to do this as it is the way the ABS brakes are set up. As my Yeti does it I have assumed (rightly or wrongly) that this is normal. As long as the brakes work as they should and stop the car then all should be OK. But it is disconcerting when you first first realise what's happening. On all my earlier cars the brake pedal has locked up solidly under pressure which makes you think something is wrong with the newer models. If anyone can say if this is as it should be it will be Johann (900000). He's a mine of useful information.

[K100RS]

Thanks everybody for shining some light on my problem.

Will take a close look when the misses comes home with the car and check to see whether the brake fluid has gone down in anyway.

Had not thought of the ABS system as my other vehicles never had this goody onboard?

It might be a bleed system to do with the ABS but I will need to dig deeper into the problem while the Yeti has a warranty running as I have not played around with ABS systems.

Did not see any leaks around the servo system after a quick check before she drove off.

The brakes work perfectly when the brake pedal is touched but of course there is always the worry that this might be a hint of problems to come. Any more thoughts on this welcome.

FlyingBrick

[Allams Skoda]

Is your Yeti a 4x4 model or have ESP as an option?

Sounds like the HBA system doing its job to me. So it isn't a problem just a feature of the car.

HBA: Hydraulic brake assistant

increases the optimal build-up of

brake power. It ensures complete

use of the brake system potential,

thus shortening the braking

distance.

I presume you are stationary when the brake pedal goes all the way down?

Edited 19 September, 2011 by Allams Skoda

[telecaster]

Is your Yeti a 4x4 model or have ESP as an option?

Sounds like the HBA system doing its job to me. So it isn't a problem just a feature of the car.

I presume you are stationary when the brake pedal goes all the way down?

Mine does the same too, but only when its stationary, so I guess you're right, its a feature not a bug.

[hmibennett]

Mine does the same too, but only when its stationary, so I guess you're right, its a feature not a bug.

+1 - hadn't thought it was or might be a problem!

[WellKnownSid]

Most diesel vehicles use a vacuum pump as there is insufficient manifold pressure (no throttle). This setup provides so much assistance, even at idle, that pushing hard on the pedal when stationary will force the brake fluid past the internal seals resulting in pedal creep.

This doesn't happen in normal braking, because you don't use anywhere near as much force on the brake pedal to actually stop the car.

The solution is normally to stop pushing the brake pedal hard when stationary, unless the engine is turned off. Once the servo is exhausted, the pedal should be rock solid.

[ejstubbs]

Is your Yeti a 4x4 model or have ESP as an option?

My 140 4x4 Elegance, which has every TLA known to Skoda, does not do what the OP described. It doesn't sound right to me.

The solution is normally to stop pushing the brake pedal hard when stationary

Maybe even, you know, use the handbrake? I'm sure it's there for a reason. Or is that one of those things like pulling over on the motorway - it makes your 'thingy' drop off?

[Jock]

My 2WD SE did this ... once ... I've never been able to repeat it, and I've had a good root around for fluid leaks, but all seems to be OK.

[K100RS]

Have now checked up more closely on the Yeti SE brake system.

It is the basic 110 two wheel drive model with no extra goodies on board ( Allams Skoda)

I cannot see any drop in the brake fluid level so will assume that there is no fluid loss plus no leaks on the garage floor from loose fitting pipes.

When the engine is running and the brake pedal is pressed down hard it does slowly move smoothly to the bottom of the floor.

If the engine is turned off and the pedal pressed down with the same force it stays in the same position once the vacuum has been used up i.e. hydraulic lock.

So it looks like a feature with ABS modern systems and somewhere there must be a bleed route for the fluid to pass bye when the engine is running.

Perhaps for some vehicle users the fact that the brakes come on is ok but having spent most of my life servicing all my cars and bikes if something feels odd I will always dig into the apparent problem before it becomes critical.

Many years ago I picked up a new BMW and put on the brakes at the first roundabout just down the road from the garage in Essex. Nothing happened at all, handbrake job plus engine braking.

Found out that the garage had left a thick coat of lanolin on the disks for protection whilst being delivered from the manufacturing company. Hence I do the maintenance and they lost the dealership.

[WellKnownSid]

Yes, you are over-pressurising the system, so the fluid is leaking past the seals. Try applying the same constant pressure at 20mph and you might end up through the windscreen!!

[K100RS]

Thanks WellknownSid

Yes fully understand what you have pointed out.

Having re filled hydraulic systems on dozens of vehicles over the years I have never managed to damage a master cylinder seal with overpressure by hand or foot.

Yes you will lock the brakes with high pressure as you correctly said but that was not my point. I have driven many police vehicles over the years and had not come across the footbrake slowly moving down on vans or cars unless there was a seal leak or spongy feel as air had got into the system.

Thanks for all you helpful comments and will have a chat with a garage technician just to educate myself on modern anti lock braking systems Sid.

[Xenophon]

Looking at the way the master cylinder has been shoehorned into place on the bulkhead, I do hope I never have the job of changing one of these. Even topping up the level looks like a significant challenge.