Soft brake pedal?!

[dannyboy759]

Just wanted if anyof you have had problems with a soft brake pedal on an Octavia?

Ive got two cars the same but on the brake pedal is firm both with the enigine on and off but the other is firm with the engine off but when you start it you can push the pedal almost to the floor!

Its the same when driving although the brakes are good but then agaion they should be with VRS discs and pads but i cant help thinking this isnt right!

Is there any known problems with the master cyclinder? or the braking system?

The car has done 190,000 so im not expecting miracles but every car that ive ever had and most of them have been BMW's have never suffered from a problem like this not even the 25 year old E30!

Do they suffer from weak flexui hoses that expand on braking?

Any ideas?

[mbames]

I can push the pedal gradually (this takes some time to complete - maybe I should time it) to the floor on mine (2001, 160k) when the engine is running..... :-( However it has quite happily passed the MOT like that for a good number of years.

I would guess one of the seals is allowing fluid passed it?

Edited 20 January, 2010 by mbames

[Guest musky]

I'd be getting them checked soonest

[dannyboy759]

I can push the pedal gradually (this takes some time to complete - maybe I should time it) to the floor on mine (2001, 160k) when the engine is running..... :-( However it has quite happily passed the MOT like that for a good number of years.

I would guess one of the seals is allowing fluid passed it?

Yeah i was thinking the same, that it could be the master letting fluid past the seals

[bodace5]

sounds like the vaccum pipe has split

Edited 20 January, 2010 by bodace5

[felicia16v]

rear calipers sticking or badly adjusted cables will give this too..

make sure the handbrake cable has a bit of slack and the arm on the cal is returning fully.. you will be suprised how much differance it makes.

also the brake fluid should be renewed every 2 years.

[dannyboy759]

The fluid has recently been changed along with the rear discs and pads and the handbrake adjustment seam fine!

[mbames]

sounds like the vaccum pipe has split

Is this the "solid" vacuum pipe from the pump, that iirc I had read is meant to fail over time?

From Honest John (http://www.honestjohn.co.uk/carbycar/index.htm?md=369):

26/3/2003: VINS TMB***1U*X2148718 to TMB***1U*X22227663 and TMB***1UY2285279 to TMB***1UY2294866: Due to a manufacturing fault, tension cracks may occur on the vacuum pipe to the brake servo in the area of the pipe connections. If a vacuum pipe leaks the brake servo loses its function requiring a lot more force on the brake pedal to stop. Check vacuum pipes and replace if necessary.

[dannyboy759]

Is this the "solid" vacuum pipe from the pump, that iirc I had read is meant to fail over time?

From Honest John (http://www.honestjohn.co.uk/carbycar/index.htm?md=369):

26/3/2003: VINS TMB***1U*X2148718 to TMB***1U*X22227663 and TMB***1UY2285279 to TMB***1UY2294866: Due to a manufacturing fault, tension cracks may occur on the vacuum pipe to the brake servo in the area of the pipe connections. If a vacuum pipe leaks the brake servo loses its function requiring a lot more force on the brake pedal to stop. Check vacuum pipes and replace if necessary.

Thats the oposite of what ive got

[bodace5]

have you checked the pipes anyway?

[karlbar2k]

I thought a soft pedal was either Air in the pipes, leaking seals or possibly weakened rubber pipes. Most likely the first two though. If the Servo vacuum is lost it will affect the amount of force being transmitted through the calipers so you will need to press harder on the pedal to get the same amount of braking. If the fluid was recently changed did they follow the correct procedure? there can be a problem with air getting trapped in the ABS pump and normal bleeding WILL NOT remove it. There is a procedure that can be followed with VAGCOM to run the ABS pump when bleeding to make sure the air is out. Another thing is if they didn't use a pressure bleeding kit and did it with the pedal they may have depressed the pedal too far causing the master cylinder seals to be damaged by grooves on the piston. HTH

[vRSLen]

You need to draw the brake fluid through the system to ensure no pockets of air

[skoda auto]

ok, this might be your cure.

Providing there is no air lock in the pipes this should work.

On the master cylynder there are two bleeding niples. Make sure your brake fluid resorvair is full and crack open each one at the time. Repeat procedure two times until fluid comes starts to leak out. Hopefully this should cure the spangeness. I have seen lot of this issues before, but mechanics dont realise there are bleeding niples on the master cylinder.

Regards

[dannyboy759]

Ill try this, many thanks

[dannyboy759]

Nope! No air in the master!

[karlbar2k]

looking like it might be air in the ABS pump

[dannyboy759]

Does nt that require a specail VAG tool?

To bleed it correctly

[ExAudiSi]

I think that it requires the diagnostic computer at the stealers to run the pump whilst bleeding the brakes. Not sure if vag-com can do the same thing though?

I think that I have a similar problem with mine and found a quite stretch of road, made sure that there was no-one behind me and stomped on the brakes to actuate the ABS. The pedal travel has been shorter since then.

[mbames]

VAG-com supports bleeding of air from the ABS pump....