Hi all,
There's a good Xantia brake problem thread currently going on elsewhere but my anomaly isn't mentioned. So here goes.
THE SYMPTOM
My 2.0i 16v 99T has on four separate occasions during the last fortnight, and each time within a few minutes of starting the car, completely failed to respond to the brake pedal being pressed. It happened once only each time and on second pressing, and thereafter, responded normally (normal on my Xantia is very good). The first time I thought I must be imagining it but four times is no illusion. Except for these four unnerving occasions the brakes behave normally.
RELATED ISSUES
About six weeks ago I replaced the front pads. While winding the pistons back into the calipers the piston gaiters on both sides split slightly. I posted on this but haven't done anything about it as yet. After only six weeks, to my mind, and even if slight corrosion has begun on the piston surface - which I haven't checked for - piston travel really shouldn't be affected.
So is this a known symptom of a completely different problem? Or are those pesky gaiters entirely to blame?
Anyone had a similar experience?
Xantia braking anomaly
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It's nasty when this happens 
I know and still have it to a small degree on my Activa.
Air is the usual culprit. Did you bleed all your brakes after swapping pads and if you bled the rears, did you bleed at least 500mL from each side as the lines arevery long and it takes a lot of LHM to fully purge them. Some run a very long pipe between the rear bleed niples and the LHM reservior to save wasting all the LHM you need to bleed.
A source of persistent air in the system can be a sphere with a leaky diaphragm allowing nitrogen gas to very slowly leak into the LHM over a period of time and fill it with bubbles. A favourite sphere for leakage, whislt not giving any other obvious symptoms is the anti-sink sphere although the rear suspension spheres can be just as guilty.
Citarobics will clear any air from the main hydraulic circuits but as the brakes are on hydraulic "dead ends" the air cannot escape except by bleeding.
Give all brakes a really good bleed after a good bout of Citarobics and see if the problem is at least temporarily resolved. If it stays good for a few days and the problem returns, suspect a sphere...
The torn gaiters on the front caliper pistons are unlikely to be the culprit.
I know and still have it to a small degree on my Activa.Air is the usual culprit. Did you bleed all your brakes after swapping pads and if you bled the rears, did you bleed at least 500mL from each side as the lines arevery long and it takes a lot of LHM to fully purge them. Some run a very long pipe between the rear bleed niples and the LHM reservior to save wasting all the LHM you need to bleed.
A source of persistent air in the system can be a sphere with a leaky diaphragm allowing nitrogen gas to very slowly leak into the LHM over a period of time and fill it with bubbles. A favourite sphere for leakage, whislt not giving any other obvious symptoms is the anti-sink sphere although the rear suspension spheres can be just as guilty.
Citarobics will clear any air from the main hydraulic circuits but as the brakes are on hydraulic "dead ends" the air cannot escape except by bleeding.
Give all brakes a really good bleed after a good bout of Citarobics and see if the problem is at least temporarily resolved. If it stays good for a few days and the problem returns, suspect a sphere...
The torn gaiters on the front caliper pistons are unlikely to be the culprit.
Jim
Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
As Jim says, air, OR it could be an ABS sensor fault.
Does this happen at very low speeds, like coasting to a stop at traffic lights and you press the pedal and for a moment nothing happens ?
Have you ever seen the ABS light come on when this happens ? If you have there is definately an ABS fault, but even without the light coming on there can still be an ABS issue.
I had this happen a number of times at slow speeds and it is very worrying - eventually it got to the point where the ABS light would sometimes come on during braking or driving, and I found the front right sensor cable was faulty - after fixing it I havn't had any re-occurances.
Trying to pin down a very intermitant problem like this can be extremely difficult though - mine played games with me for over 6 months before I finally nabbed it, so I would suggest following up on bleeding the brakes first and see if you have any further occurances.
Regards,
Simon
Does this happen at very low speeds, like coasting to a stop at traffic lights and you press the pedal and for a moment nothing happens ?
Have you ever seen the ABS light come on when this happens ? If you have there is definately an ABS fault, but even without the light coming on there can still be an ABS issue.
I had this happen a number of times at slow speeds and it is very worrying - eventually it got to the point where the ABS light would sometimes come on during braking or driving, and I found the front right sensor cable was faulty - after fixing it I havn't had any re-occurances.
Trying to pin down a very intermitant problem like this can be extremely difficult though - mine played games with me for over 6 months before I finally nabbed it, so I would suggest following up on bleeding the brakes first and see if you have any further occurances.
Regards,
Simon
Simon
1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White
2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White
2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
Thanks both.
Jim - the air-in-the-system hypothesis begs the question: why aren't the brakes permanently affected? Is there an 'air trap' somewhere that - once the air is trapped - stops it interfering with braking until certain conditions 'untrap' the air again? In answer to your question though, no, I didn't bleed at all after changing the pads. Didn't think I'd need to since I couldn't see how any air would have got introduced during pad change.
Simon - yes! - it happens at low speeds, such as when pulling up at lights. What's unnerving about this is that you're generally closer to the car in front than while 'normal' driving at higher speeds. I don't EVER remember seeing the ABS warning light come on since I've had the car (six months). Sounds like this is irrelevant though. Maybe I dinged the sensor/wiring while changing the pads? Was very careful, but I guess it's possible.
Couple of things there to try/keep an eye on though, so thanks both. Will post if/when any progress with this.
Jim - the air-in-the-system hypothesis begs the question: why aren't the brakes permanently affected? Is there an 'air trap' somewhere that - once the air is trapped - stops it interfering with braking until certain conditions 'untrap' the air again? In answer to your question though, no, I didn't bleed at all after changing the pads. Didn't think I'd need to since I couldn't see how any air would have got introduced during pad change.
Simon - yes! - it happens at low speeds, such as when pulling up at lights. What's unnerving about this is that you're generally closer to the car in front than while 'normal' driving at higher speeds. I don't EVER remember seeing the ABS warning light come on since I've had the car (six months). Sounds like this is irrelevant though. Maybe I dinged the sensor/wiring while changing the pads? Was very careful, but I guess it's possible.
Couple of things there to try/keep an eye on though, so thanks both. Will post if/when any progress with this.
Does your ABS light up when you turn the ignition on???
Maybe the bulb has either been removed or has blown. Replacing the bulb is easy, remove the instrument panel and replace it and any others too at that point.
If it lights up after you start the engine, It may be that one of your sensors has gone, possibly the front passenger side one.
look up under abs in search and there is a lot of info about abs
Paul
Maybe the bulb has either been removed or has blown. Replacing the bulb is easy, remove the instrument panel and replace it and any others too at that point.
If it lights up after you start the engine, It may be that one of your sensors has gone, possibly the front passenger side one.
look up under abs in search and there is a lot of info about abs
Paul
1xAmi,3xGS,2xBx,2xAX,2xSaxo,1xXantia mk I,2xXantia MkII,1xC1,2xC2,
If it's happening at slow speeds then I'd start by checking a couple of other bits.
First, are the brakes pulsey?
If so do they pulse more as engine revs die?
Also does you're car make a frequent (1second to 10 seconds) ticking noise from under the bonnet right at the front of the car when idling?
I think you're problem may be the accumulator sphere.
It's not a big deal, just see if it ticks and get back to us later.
Don't know if you've changed spheres before but it's not a hard job anyway.
I wouldn't worry about the gaitors much, my last car had really torn ones and the brakes were fine for a year.
First, are the brakes pulsey?
If so do they pulse more as engine revs die?
Also does you're car make a frequent (1second to 10 seconds) ticking noise from under the bonnet right at the front of the car when idling?
I think you're problem may be the accumulator sphere.
It's not a big deal, just see if it ticks and get back to us later.
Don't know if you've changed spheres before but it's not a hard job anyway.
I wouldn't worry about the gaitors much, my last car had really torn ones and the brakes were fine for a year.