braking problem

[pasco]

I have a fabia vrs on a 54 reg and i have a problem with my brakes. when pressing down on the pedal i can get almost to the floor however when pumped the pedal then goes solid.

after pumping if i leave pressure on the pedal it once again drops to the floor.

The first thing i tried were the obvious, i bled the brake system all around and put new fluid into the system. i think checked that all the brake pads and discs were in good condition.

I am stuck on where to go from here.

Ive heard of a problem with the master cylinder and a pipe which cracks/leaks, can anyone confirm that this may be my problem and if so what the method for fixing this is??

Cheers lads

A

[MoggyTech]

It's called diesel creep and is normal due to the constant vacuum available from the tandem pump driven by the camshaft. However, if you feel it's excessive have it checked by a specialist. Some checks you can do yourself.

Engine off, pump brake pedal till it goes hard and hold it there with a lot of force, if it doesn't creep down, the hydraulics are leak free.

Keep pedal pressed with moderate pressure, and start engine, pedal will creep down about 3 inches (servo OK).

What you are actually doing when testing at present, is applying massive over pressure in the brake system, and you can damage the seals in the system.

If you feel it's really bad, replace brake fluid and all brake pads and discs if they are worn.

More info here

http://www.brakesint.co.uk/technical.html#techNote202

[pasco]

It's called diesel creep and is normal due to the constant vacuum available from the tandem pump driven by the camshaft. However, if you feel it's excessive have it checked by a specialist. Some checks you can do yourself.

Engine off, pump brake pedal till it goes hard and hold it there with a lot of force, if it doesn't creep down, the hydraulics are leak free.

Keep pedal pressed with moderate pressure, and start engine, pedal will creep down about 3 inches (servo OK).

What you are actually doing when testing at present, is applying massive over pressure in the brake system, and you can damage the seals in the system.

If you feel it's really bad, replace brake fluid and all brake pads and discs if they are worn.

the brake pads and discs are not worn and the fluid is brand new and the system has just been bled of all air bubbles. so there is definitely NO air in the system.

the brake pedal drops to the floor wether the engine is on or off. i am not exerting masses of pressure on the pedal to do this. just applying a normal pressure as you would od if you were coming to a rest at a set of traffic lights....

[MoggyTech]

the brake pads and discs are not worn and the fluid is brand new and the system has just been bled of all air bubbles. so there is definitely NO air in the system.

the brake pedal drops to the floor wether the engine is on or off. i am not exerting masses of pressure on the pedal to do this. just applying a normal pressure as you would od if you were coming to a rest at a set of traffic lights....

Faulty master cylinder or leaking servo diaphragm. Could also be corroded ABS unit valve seats, if ABS hasn't been activated for some time.

[pasco]

Faulty master cylinder or leaking servo diaphragm. Could also be corroded ABS unit valve seats, if ABS hasn't been activated for some time.

If this was an issue with the abs would this not throw up a fault on vagcom or a dashlight?

I have had a browse about on here and have found that there is a very common issue with the servo vaccumm hose, apparantley these can split. I will check this, when i get home this evening. if there is air getting into the system via that hose then this would explain why it feels like there is air in the system when i know that there wasnt any when i bled and re-filled the system.

Does this sound like a decen thing to try as a first step?

[MoggyTech]

If this was an issue with the abs would this not throw up a fault on vagcom or a dashlight?

I have had a browse about on here and have found that there is a very common issue with the servo vaccumm hose, apparantley these can split. I will check this, when i get home this evening. if there is air getting into the system via that hose then this would explain why it feels like there is air in the system when i know that there wasnt any when i bled and re-filled the system.

Does this sound like a decen thing to try as a first step?

The cracked servo hose to tandem pump, usually results in a rock hard pedal, with no servo assistance available. It only carries vacuum air and is not connected in any way to the brake fluid side of things.

If you can get pedal creep with the engine off and all vacuum depleted, then fluid is leaking past a seal, or a flexi hose is bulging.

Worth noting, if brakes on these cars are bled the old fashioned way, e.g. pumping the brake pedal to the floor, you can reverse the master cylinder seals!

The brakes should ideally be bled using VAGCOM to modulate the ABS valves, and the brakes pressure bled, or a block of wood placed under the brake pedal during pump type bleeding, to prevent the pedal going down too far.

[KenONeill]

For the corroded valve seats to throw a fault, the valve travel would have to be changed, and monitored.

The servo vacumn hose operates on the vacumn side of the servo (d'oh!!), and has no direct connection to the hydraulic fluid that air could pass through. Also, I would expect it to reduce or eliminate vacumn, giving a short and heavy pedal, rather than a long and soft one.

[pasco]

The cracked servo hose to tandem pump, usually results in a rock hard pedal, with no servo assistance available. It only carries vacuum air and is not connected in any way to the brake fluid side of things.

If you can get pedal creep with the engine off and all vacuum depleted, then fluid is leaking past a seal, or a flexi hose is bulging.

Worth noting, if brakes on these cars are bled the old fashioned way, e.g. pumping the brake pedal to the floor, you can reverse the master cylinder seals!

The brakes should ideally be bled using VAGCOM to modulate the ABS valves, and the brakes pressure bled, or a block of wood placed under the brake pedal during pump type bleeding, to prevent the pedal going down too far.

thanks for the advice, the brakes were bled the old fashioned way which if you are correct have resulted in the master cyclinder seals being reversed. I think the best thing to do would be to take it to my local garage and see what they can advise me with. I know the owner and im sure that he will bleed the brakes in the correct way intended.

if the problem is with the master cylinder seals are these replaceable or would a replacement of the whole master cylinder be needed?

For the corroded valve seats to throw a fault, the valve travel would have to be changed, and monitored.

The servo vacumn hose operates on the vacumn side of the servo (d'oh!!), and has no direct connection to the hydraulic fluid that air could pass through. Also, I would expect it to reduce or eliminate vacumn, giving a short and heavy pedal, rather than a long and soft one.

ahh i see it involves the vacumm, i hadnt thought about that. I will check it anyway even though this obviously isnt going to be the main cause of my issue.

[giandougl]

NORMAL MATE WITH BRAKES, STOP WORRYING.

[forge_garage_VAG]

HI

Dos the pedel creep to the floor with and with out the engine running??

If it does its most likely to be the master cylinder.

A fault servo circuit would result in a rock hard pedel with reduced braking effort.

Chris K

[pasco]

NORMAL MATE WITH BRAKES, STOP WORRYING.

its not normal at all, i drove my friends vrs that is the same age and spec. his brakes have a much better feel than mine and the braking was dramatically improved over mine.

HI

Dos the pedel creep to the floor with and with out the engine running??

If it does its most likely to be the master cylinder.

A fault servo circuit would result in a rock hard pedel with reduced braking effort.

Chris K

it creeps to the floor with the engine both running and not. because of this the concensus is that i may have an issue with the master cylinder?

the pedal is most defininitely NOT rock hard!

[forge_garage_VAG]

hi

if you do your own repairs and are ok with it

check for external leaks are you loosing fluid??

I would go for a new cylinder.

[pasco]

hi

if you do your own repairs and are ok with it

check for external leaks are you loosing fluid??

I would go for a new cylinder.

not loosing any fluid, bled the brakes 2 days ago and have done 70 miles since and fluid level hasnt moved at all.

looks like it will have to be a new cylinder then, i am handy with the spanners and do alot of my work myself, is this a job advised to take on or a job for a garage. at the end of the day i hold my life in that pedal, if the car doesnt stop then im in trouble.

[Dox]

Whats the full story? Have you just done a fuid change or has the hydraulic system been broken to replace a caliper or similar?

I had similar problems with an Audi, I bought a Sealey pressure bleeder and cracked open all connections on the M/C, calipers and ABS unit one by one until fluid came out and now have a perfect pedal - air was trapped somewhere and by pressurising the system and opening the hard line and flexi connections it purged the air out.

HTH

[pasco]

Whats the full story? Have you just done a fuid change or has the hydraulic system been broken to replace a caliper or similar?

I had similar problems with an Audi, I bought a Sealey pressure bleeder and cracked open all connections on the M/C, calipers and ABS unit one by one until fluid came out and now have a perfect pedal - air was trapped somewhere and by pressurising the system and opening the hard line and flexi connections it purged the air out.

HTH

i bought the car a week ago. in the service history it says the braking system had new fluid and was repressurised in february. i knew something was up with the pedal as soon as i felt it, so knocked the guy down on the price for that. the other night me and my mate bled the system via each caliper whilst i was pumping on the brake pedal. we then refilled the fluid and then went around the car again to make sure there was no air around the caliper system.

i am wondering wether it is worth getting hold of a master cylinder and then getting a garage to fit it so that they bleed the system correctly and let them do the job...

[Dox]

i bought the car a week ago. in the service history it says the braking system had new fluid and was repressurised in february. i knew something was up with the pedal as soon as i felt it, so knocked the guy down on the price for that. the other night me and my mate bled the system via each caliper whilst i was pumping on the brake pedal. we then refilled the fluid and then went around the car again to make sure there was no air around the caliper system.

i am wondering wether it is worth getting hold of a master cylinder and then getting a garage to fit it so that they bleed the system correctly and let them do the job...

I had a M/C fitted to the Audi as the pipework needed moving to the oposite side - still crap, I bought the bleeder and bled at the nipples, still poor, then did as above and the pedal went hard and has been ever since.

By bleeding using the foot brake the M/C seals go beyond there normal travel and this can damage the seals, its much better to bleed modern cars with a pressure bleeder IMO.

Pressure bleeder

I paid £55 for mine off ebay delivered

[pasco]

I had a M/C fitted to the Audi as the pipework needed moving to the oposite side - still crap, I bought the bleeder and bled at the nipples, still poor, then did as above and the pedal went hard and has been ever since.

By bleeding using the foot brake the M/C seals go beyond there normal travel and this can damage the seals, its much better to bleed modern cars with a pressure bleeder IMO.

Pressure bleeder

I paid £55 for mine off ebay delivered

thanks for the advice, the only thing is that if the seals are already damaged in the master cylinder this will mean that using one of these pressure bleeders wont actually do anything. do you know what i mean?

[Dox]

thanks for the advice, the only thing is that if the seals are already damaged in the master cylinder this will mean that using one of these pressure bleeders wont actually do anything. do you know what i mean?

Yes I know, but as I've said My M/C was changed by a garage and I still had the same issue (I swapped the M/C for nothing effectivelly) and you'll still have to bleed the new M/C.

You can also bleed the system and operate the ABS pump with Vagcom to purge any air.

Clamp all 4 flexis, is the pedal better?

[sepulchrave]

The system appears to get airlocked somewhere in the ABS mod and you need to shift a lot of fluid to get it through, you simply cannot do this using the brake pedal.

Invest the £15 and get a litre of brake fluid and change the lot out.

I replaced my master cylinder and it didn't make any difference, it was trapped air.

What kind of idiot tells you that your faulty brakes are normal, appalling advice like that could lead to a serious accident.

Luckily you have the sense to ignore this stupidity, I just hope whoever decides to jack-in-the-box and give dangerous advice will restrict their forum activities to brainless comments about how lush peoples wheels look in future!

[KenONeill]

On the bleeding point, the way to bleed these cars is either with a vacumn bleeder, or a pressure bleeder running no more than 1bar overpressure, and VCDS. You need the VCDS to bleed the ABS valve block properly.

Dougal, I'd trust someone who's done a back to back test on 2 cars over "some guy on the interweb" as to whether one of the tested cars has a bad pedal or not.

[pasco]

Yes I know, but as I've said My M/C was changed by a garage and I still had the same issue (I swapped the M/C for nothing effectivelly) and you'll still have to bleed the new M/C.

You can also bleed the system and operate the ABS pump with Vagcom to purge any air.

Clamp all 4 flexis, is the pedal better?

decision made then via the advice of other people aswell. i wil not change the master cylinder as this sounds like it would be a waste of time. it sounds like a full flush and bleed of the whole system is what is needed and then take it from there onwards if the problem still occurs.

The system appears to get airlocked somewhere in the ABS mod and you need to shift a lot of fluid to get it through, you simply cannot do this using the brake pedal.

Invest the £15 and get a litre of brake fluid and change the lot out.

I replaced my master cylinder and it didn't make any difference, it was trapped air.

What kind of idiot tells you that your faulty brakes are normal, appalling advice like that could lead to a serious accident.

Luckily you have the sense to ignore this stupidity, I just hope whoever decides to jack-in-the-box and give dangerous advice will restrict their forum activities to brainless comments about how lush peoples wheels look in future!

I thought it was stupid of whoever it was who said that to actually put that i follow the same philosophy as you "sepulchrave" if youve got nothing of any help to say that dont say it at all. In this situation where the brakes on someones car are concerned people should just think before they type.

thanks for your advice though, i am being led to think that it will just be an issue with a serious amount of trapped air.

With engine running to press continuously down on the foot-brake will see and feel it drop almost (almost) to the floor.

Took this up with a SKODA mechanic, who very detailed explained it's to do with car being a diesel and the vacuum reserve in the brake servo.

He further had me go with him onto the forecourt and test out another year older Fabia VRS 2004, with exactly the same effect.

Further members on this site confirmed what I was told was correct.

ok thanks for that advice but strangely enough it does not seem to tie in with anything that anyone else has said on this thread. I will be taking the car to an independent garage tonight so i can get there mechanics opninion on the matter and see wether that ties in with what has been said on here.

[pasco]

On the bleeding point, the way to bleed these cars is either with a vacumn bleeder, or a pressure bleeder running no more than 1bar overpressure, and VCDS. You need the VCDS to bleed the ABS valve block properly.

Dougal, I'd trust someone who's done a back to back test on 2 cars over "some guy on the interweb" as to whether one of the tested cars has a bad pedal or not.

thanks ken, this seems to be the general concensus of the matter so i will say this to the garage when i get to them and see if they agree with what has been said.

thanks

a

[r32]

I think my car has similar symptoms as yours. The first press of the brake pedal is always "soft" and sometimes the pedal will go nearly to the floor. The second press the pedal is hard.

I'd assumed it was air in the brakes and was planning to have them bled at the next service (in 2 weeks). Although I am concious that there are a lot of complaints from owners about the vrs brakes, so was unsure that would make any difference. I also couldn't remember if they were always this way... (I've had the car 4 years)

[pasco]

doesnt sound the same as mine mate, my pedal feel is always the same wether i have been using them alot on a town journey or wether i get in the car first thing in the morning.

[hussarman]

NORMAL MATE WITH BRAKES, STOP WORRYING.

Am I reading this correctly? Must be a lunatic.