Xantia 2.1TD Brakes

f00lzz · Post by **f00lzz** » 26 Sep 2010, 02:13

I used my Sons 2.1 today. He told me that ''after starting and when the big STOP light goes out you have to pump the brake pedal a few times or you won't have any brakes'' I duly followed his instructions and when I got to the 'pedal pumping' stage the STOP light gave a few flashes and all became normal! First time I have heard of this anomaly and as this is the car in which he ferries my youngest two Grandchildren around in... I'm a little concerned. Any thoughts?

Xaccers · Post by **Xaccers** » 26 Sep 2010, 08:24

Flat accumulator sphere perhaps?
Let the car idle, pop the bonnet and listen for a click/tick.
There should be at least 30 seconds between clicks/ticks.
If its less then change the accumulator sphere and unless you know it has been changed in the last 3 years also change the rear accumulator known as the anti sink sphere.
Spheres are approx £22 from gsf car parts.

Also check the lhm level with the car idling and set on high. The orange float should be between the two red lines on the inspection bubble on the lhm resevoir.

Also check the hydraulic pump for leaks, normally from the 19mm nut with a pipe coming out of it and further round the pump there's a similar 19mm blanking plate. The o-rings go but are very cheap and easy to replace.

The pump has two outputs, one for the power steering and the other runs the suspension and brakes. There is no master cylinder for the brakes, just direct pressure from the pump. The acc sphere works as a pressure storage and helps absorbe any pressure spikes. So it is your emergency reserve for the brakes should the pump stop running (due to the aux belt snapping for instance).

f00lzz · Post by **f00lzz** » 26 Sep 2010, 09:05

Hi. Thanks for the quick reply, I've still got his car so will check the obvious things this morning, I'm hoping it's nothing 'sphere wise' as these were all changed by Pleides in July/August so maybe a leak! This only occurs after being left for any length of time i.e. overnight, everything appears normal till first thing next day..

citronut · Post by **citronut** » 26 Sep 2010, 09:07

i have never seen/heard of this type of symton with hydraulic citroen,s,

the only one i have seen experienced is if there is air in the brake circuit the first pedel presure (normal braking) dose nout, but the second presure (harder) locks the brakes up,

i do not understand how a hydraulic citroen (apart from C5's) can give this effect, because even if there is low hydraulic presure, the working presure how ever low is there all the time,

obviously unless there is none,

regards malcolm

f00lzz · Post by **f00lzz** » 26 Sep 2010, 09:46

Ok.. Just had a look, took video camera with me for evidence gathering...
Not a sign of a problem, started up STOP light went out pumped the pedal (brakes were hard) no flashing STOP light! No leaks, LHM at Max my hearing isn't good enough to hear accumalator ticks over a 2.1 Diesel knock (V6 Rocks).
So, all seemed as it should. However, the car is normally parked on a sloping drive, could this have an affect?

f00lzz · Post by **f00lzz** » 26 Sep 2010, 09:55

Thinking about your comment Malcolm about air/gas in the system.. As mentioned he recently had all the spheres changed and as some of the spheres replaced were definately knackerd I suppose he could have gas in the 'dead ends' but I can't figure how this causes the STOP light to flash etc.

addo · Post by **addo** » 26 Sep 2010, 10:05

What if the pump suction line were drawing air to start with?

dnsey · Post by **dnsey** » 26 Sep 2010, 10:10

In the absence of any obvious faults, I'd try opening the bleed screw on the pressure regulator for 30 seconds or so. Close the screw, exercise the suspension, steering and brakes, then re-bleed.

f00lzz · Post by **f00lzz** » 26 Sep 2010, 10:17

Ok I'll give that a shot.. thanks

Kowalski · Post by **Kowalski** » 26 Sep 2010, 16:57

What happens if you don't pump the pedal, will the light go out and the brakes work normally?

I remember with one of my Xantia's that when you started the engine after it hadn't been run for a few hours the STOP light would illuminate and the brakes wouldn't work. If you waited for the stop light to go out, the brakes would work just fine, i.e. there was no residual pressure in the accumulator sphere and the pump output was going into pressurising it, once it had done so everything worked properly. I think this was a sign that the accumulator sphere was getting old and didn't have enough gas in it, so I replaced that sphere and the problem went away.

If your son's car is mirroring what mine did, it might not be pumping the brakes that makes them work, it might just be the delay while you pump the brakes.

f00lzz · Post by **f00lzz** » 26 Sep 2010, 17:50

@Kowalski. The procedure followed is 1. start engine, 2. wait till STOP light extinguishes, 3. Press brake pedal repeatedly STOP light flashes 2 or 3 times THEN and only then you have brakes.. apparently his partner had a close call when she drove off after the initial start up and STOP light extinguished only to collide with a set of big blue gates whilst turning the car out of the drive all because she had no brakes. I have taken dnsey's advise and my Son now has his car back... we will know in the morning if things have improved!!!

Not a major slope.. but enough to cause panic if the brakes don't work!

citronut · Post by **citronut** » 26 Sep 2010, 18:40

ok so in light of what you last said,

this happens when the system presure has not fully pumped up, so in you press the brake pedel you are drawing presure from the system, which as it had not quite got up full presure it causes the stop lamp to briefly light, maybe on and off a couple or so times,

so this means its not the pumpping of the pedel that aparently getting the brakes working again,

also if you cant hear the PR tick rate place a long length of dowl on the PR body and the other end to your best ear,

regards malcolm

f00lzz · Post by **f00lzz** » 26 Sep 2010, 19:09

I don't think I am making myself clear Malcolm.. If you start the engine and the STOP light extinguishes after a few seconds then in theory everying is ready.... BUT there are no brakes... unless you pump them a few times, during which the STOP lamp flashes... then you have brakes! Non of my other Xantias or XM have ever done that!

Xaccers · Post by **Xaccers** » 26 Sep 2010, 20:26

f00lzz wrote:I don't think I am making myself clear Malcolm.. If you start the engine and the STOP light extinguishes after a few seconds then in theory everying is ready.... BUT there are no brakes...

Even if you leave the car idling for 10 minutes without touching the brakes?

Dommo · Post by **Dommo** » 26 Sep 2010, 20:39

Xac wrote:
f00lzz wrote:I don't think I am making myself clear Malcolm.. If you start the engine and the STOP light extinguishes after a few seconds then in theory everying is ready.... BUT there are no brakes...
Even if you leave the car idling for 10 minutes without touching the brakes?

I would try what Xac says in this post personally, leave it for a good minute after the stop light has extinguished to see if they work then.