Hi,

My dad has just had new brake pads and disks put on all round on his octy today and when he tested the brakes the car comes to a stop as normal but if you hold the pedal down it then moves a further 1.5-2 inches down. It only happens when holding your foot on the pedal and only started after the pads and disks were changed. The garage that fitted them said it could be the master cylinder but it's strange it's only just started to happen.

Any suggestions?

Thanks

Could be air in the system, might be worth a bleed to be sure?

Were the pistons in the calipers screwed back in fully prior to refitting?

Did they bleed the brakes?

I've heard of similar issues when a certain type of bleeding is used on VAG systems.... as I understand it, they sort themselves out eventually. That said, I would get it checked out since it's a fault with such an important part of the car.

I'd suspect a bleeding issue, if it was done. The order you bleed the brakes on an Octy with ABS is not the usual "work towards the master cylinder"!

Air in the lines will tend to give sponginess and you should feel it when pressing the brakes. If the pedal goes down further after prolonged pressure this would tend to indicate the master cylinder seals are fubar'd. The problem is that seal damage can be caused when people are bleeding the brakes after putting on new discs/pads. They bleed the brakes by pushing the pedal right to the floor...normal wear and tear can give a ridge in the bore of the master cylinder caused by the piston/seals going back and forth this is not usually a problem as the seals expand a little to maintain a good seal ..the problem is when you push the pedal to the floor during bleeding. Your brake pedal [and therefore the piston/seals in the master cylinder] never normally goes down past the ridge until , that is, when you floor the pedal ..the seals travel over the ridge and can get either popped out of shape or just ripped.

Not much use to you now but for anyone else reading...NEVER floor the pedal when bleeding, and if you have ABS then when pushing the pistion back into the caliper crack the bleed nipple open on the caliper otherwise fluid will go back into the pump unit and may flip the seals in the ABS solenoids in the pump unit as it makes its way back to the master cylinder..[not sure if this is true for VAG brakes but it never hurts to follow this technique..]

Thanks for all your replies.

bjorn: I'm not sure on that and my dad probably wouldn't know either he just sat in the waiting room and let them get on with it.

All: He said when he went back in to tell them about the fault they said we'll bleed the brakes again, so I'm guessing they did it twice.

JRHartley: Thanks for that info I'm sure it will help alot of people and is something my dad can use when he goes back to see them as it sounds like they may have fubar'd the seals as you say.

Thanks again everyone.

Thanks for all your replies.

bjorn: I'm not sure on that and my dad probably wouldn't know either he just sat in the waiting room and let them get on with it.

All: He said when he went back in to tell them about the fault they said we'll bleed the brakes again, so I'm guessing they did it twice.

JRHartley: Thanks for that info I'm sure it will help alot of people and is something my dad can use when he goes back to see them as it sounds like they may have fubar'd the seals as you say.

Thanks again everyone.

Go steady as I'm not accusing the garage of fubaring it..just that if it was me and the fault appeared as soon as the pads were done then thats my opinion as to what caused them to go...doesn't necerssarily mean they weren't on their way out anyway..., tread carefully and don't go accusing anyone.. just bear in mind that bleeding by pushing to the floor is as a possible cause for seal failure... the mastercylinder would still need to have been beyond its best years as well and that would be beyond the fault of the garage..

a seal change should hopefully rectify it if thats what the problem is

Not much use to you now but for anyone else reading...NEVER floor the pedal when bleeding, and if you have ABS then when pushing the pistion back into the caliper crack the bleed nipple open on the caliper otherwise fluid will go back into the pump unit and may flip the seals in the ABS solenoids in the pump unit as it makes its way back to the master cylinder..[not sure if this is true for VAG brakes but it never hurts to follow this technique..]

What a load of rubbish!!

"NEVER Floor the pedal when bleeding" well how are you going to getthe air out ?

and there is no need to crack the bleed nipple, that is where the air gets in the system

YOU NEVER OPEN THE BLEED NIPPLE UNLESS YOU NEED TO ! either after cylinder change or change of fluid.

and as far as fliping the seals the fluid has to travel both ways, as that is how the system works

Radiotwo

Don't worry I never actually got to talk to my dad before he took the car back in so he never accused anyone so it's all good. Apparently the service manager looked at it and there was air in the system. They sorted it out and now all is good. Thanks for all your comments.

What a load of rubbish!!

"NEVER Floor the pedal when bleeding" well how are you going to getthe air out ?

In exactly the same way the only difference is you push the pedal half way down instead of all the way ..just takes twice as long to do. Just because Skoda make the brake pedal travel 4 " until it buries itself into the carpet doesn't mean you have to push it down that far..What if they allowed you 5" of travel, does that now mean you have to push it 5" on every stroke to bleed the brakes instead of 4" ?

and there is no need to crack the bleed nipple, that is where the air gets in the system

You will only get air in the system if you keep the bleed nipple open when you take your foot off the pedal, as I am sure you are well aware, you're supposed to close the nipple before taking your foot of the brake pedal to stop air going back in....thats why its easier to get someone to do the pedal pressing as you open and close the nipple...or just use a bleed kit and you can keep the nipple open until you have bled the line .

What ever way you do it, any time the bleed nipple is opened it should be attached by hose immersed into a reservoir of brake fluid so any suck back will take fliud back in to the brake cyliners not air..

YOU NEVER OPEN THE BLEED NIPPLE UNLESS YOU NEED TO ! either after cylinder change or change of fluid.

Entirely your choice they are there to be used as you see fit.

and as far as fliping the seals the fluid has to travel both ways, as that is how the system works

Yes, during normal brake use only a small amount of fluid moves against the solenoids when you take your foot off the brake pedal . But in a typical ABS system the solenoids will only be Armed solenoids if the ABS system is working and is activated by turing on the ignition [how many people bleed with the ignition on?]If you have an ABS system fault or the ignition is switched off the ABS ECU will not arm the ABS relay and will set the solenoids to a default position where the braking system will still function as a conventional non-ABS braking system...for obvious safety reasons. In their operational positions they will move as necessary when told by the ECU to accomodate this fluid movement. However..pumping a large volume of fluid back against the solenoids when bleeding the braking system will force against the solenoids and and may damage the seals..

Damage to ABS systems is well documented..google it if you don't believe me

My point is that for the sake of cracking open the nipples and only pushing the pedal half way down and either getting someone to help press the pedal or spend a tenner on an easy bleed kit you can lower the risk of wrecking your master cylinder seals and possibly the ABS.

It will cost you nothing other than an extra few minutes

What a load of rubbish!!

Entirely your opinion which your fully entitled to but seeing as your so obviously of the opposite opinion to me would you care to enlighten us as to your thoughts as to the problems AvRS is having maybe why his master cylinder seals MAY have gone at the same time the brakes were bled ?

At the end of the day I am offering advice and assistance and anyone is free to take from this advice what they will/want its a free country. People can either trust me or not ,and I try, where ever possible to explain the advice I give and the reasons why I am giving it so that they can make their own mind up.

I am not in the habit of offering any advice that I think is hearsay or rumour and may cause someone to damage their car or cause unecessary expense. If someone doesn't agree with me or feels/knows I have given incorrect information then please by all means feel free to offer constructive criticism or post up a correction if I am wrong, I don't mind..the important thing is that the member whose thread it is gets the necessary help....but simply dismissing what advice I have given as being 'A load of rubbish' yet failing to offer any reasoned argument as to why I am incorrect or offering any other opinion / information is I just not helpful.

Anyway , as far as this thread goes AvRS's dad, IMHO, has either got air in the brakes.. which is more likely to give a spongy pedal but since he has explained it was sinking to the floor which is either a fluid leak, air in the master cylinder or master cylinder seals and my advice is given as to why I chose that in my opinion its more liely to be the Master cylinder seals

My advice regarding Bleeding and ABS systems is my opinion on how to minimise the RISK of potential damage that can occur regardless of how relatively low the risk. Take it or leave it. It will cost you nothing other than a few extra minutes.

J [will not posting about his ABS/Master cylinder seals being fubr'd] R Hartley

In exactly the same way the only difference is you push the pedal half way down instead of all the way ..just takes twice as long to do. Just because Skoda make the brake pedal travel 4 " until it buries itself into the carpet doesn't mean you have to push it down that far..What if they allowed you 5" of travel, does that now mean you have to push it 5" on every stroke to bleed the brakes instead of 4" ?

You will only get air in the system if you keep the bleed nipple open when you take your foot off the pedal, as I am sure you are well aware, you're supposed to close the nipple before taking your foot of the brake pedal to stop air going back in....thats why its easier to get someone to do the pedal pressing as you open and close the nipple...or just use a bleed kit and you can keep the nipple open until you have bled the line .

What ever way you do it, any time the bleed nipple is opened it should be attached by hose immersed into a reservoir of brake fluid so any suck back will take fliud back in to the brake cyliners not air..

Entirely your choice they are there to be used as you see fit.

Yes, during normal brake use only a small amount of fluid moves against the solenoids when you take your foot off the brake pedal . But in a typical ABS system the solenoids will only be Armed solenoids if the ABS system is working and is activated by turing on the ignition [how many people bleed with the ignition on?]If you have an ABS system fault or the ignition is switched off the ABS ECU will not arm the ABS relay and will set the solenoids to a default position where the braking system will still function as a conventional non-ABS braking system...for obvious safety reasons. In their operational positions they will move as necessary when told by the ECU to accomodate this fluid movement. However..pumping a large volume of fluid back against the solenoids when bleeding the braking system will force against the solenoids and and may damage the seals..

Damage to ABS systems is well documented..google it if you don't believe me

My point is that for the sake of cracking open the nipples and only pushing the pedal half way down and either getting someone to help press the pedal or spend a tenner on an easy bleed kit you can lower the risk of wrecking your master cylinder seals and possibly the ABS.

It will cost you nothing other than an extra few minutes

Entirely your opinion which your fully entitled to but seeing as your so obviously of the opposite opinion to me would you care to enlighten us as to your thoughts as to the problems AvRS is having maybe why his master cylinder seals MAY have gone at the same time the brakes were bled ?

At the end of the day I am offering advice and assistance and anyone is free to take from this advice what they will/want its a free country. People can either trust me or not ,and I try, where ever possible to explain the advice I give and the reasons why I am giving it so that they can make their own mind up.

I am not in the habit of offering any advice that I think is hearsay or rumour and may cause someone to damage their car or cause unecessary expense. If someone doesn't agree with me or feels/knows I have given incorrect information then please by all means feel free to offer constructive criticism or post up a correction if I am wrong, I don't mind..the important thing is that the member whose thread it is gets the necessary help....but simply dismissing what advice I have given as being 'A load of rubbish' yet failing to offer any reasoned argument as to why I am incorrect or offering any other opinion / information is I just not helpful.

Anyway , as far as this thread goes AvRS's dad, IMHO, has either got air in the brakes.. which is more likely to give a spongy pedal but since he has explained it was sinking to the floor which is either a fluid leak, air in the master cylinder or master cylinder seals and my advice is given as to why I chose that in my opinion its more liely to be the Master cylinder seals

My advice regarding Bleeding and ABS systems is my opinion on how to minimise the RISK of potential damage that can occur regardless of how relatively low the risk. Take it or leave it. It will cost you nothing other than a few extra minutes.

J [will not posting about his ABS/Master cylinder seals being fubr'd] R Hartley

I agree 100% with your advice regarding only pushing the brake pedal half way down during bleeding.

Brake master cylinders on some Vauxhall/Opel models suffer damaged seals during bleeding if the brake pedal is pushed all the way to the floor. (Displaying exactly the same symptoms as in this case).