Anders
Isn't the safety valve 'self monitoring?'
What I mean is that as it opens up the feed to the suspension it also operates the warning light switch and puts out the warning light.
I had a problem and suspected mine but having looked at the diagram in Haynes I decided it was really rather a nice bit of engineering and deserved to be left alone!
If the light is working properly then if it remains out there must be enough presssure for the brakes to work. I see that its isolation pressure is 80 bar and the suspension supply pressure is 100 bar. i would have thought that to get pulsing at the brakes the pressure would have to fall far below this figure.
For a long time I had a problem with the warning light coming on while I was driving. At all times the brakes functioned perfectly and that is why I suspected the 'Messenger' as it were. It eventually turned out that a non-genuine pas splitter had been wrongly assembled with the ball bearing the wrong side of its support. I sorted it about 3 months ago and haven't seen the warning light since.
Jeremy
Xantia brake pedal pulsing
Moderator: RichardW
Jeremy -
I wrote :
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"> ... connected, 1 wire attached for low pressure warning lamp & ... <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
- you're right - the safety valve has one more purpose : monitoring the system pressure.
At what exact pressure it opens for the suspension - seems to be somewhat depending on Citroenmodels & years - therefore the approx 90bar figure.
It does not do any limiting - it simply opens for the suspension when the system pressure is high enough to also feed the suspension. That's why the designation : safety/priority valve.
As you know the system pressure in any hydraulic Citroen is pendling around some 160bar - regulated by the regulator's valves - which means the system presure in fact vary between some 150-170bar - over the "click" sound time interval.
This pressure is constantly available in the brake & suspension feeds FROM the safety valve.
Please don't take these pressure values for exact terms - they are leading figures - which they also should be taken as in Haynes & other documentation.
There are absolute max & min figures which should only be adhered to if accurate pressure test equipment is connected to the system for testing components to spec's.
But such testing I believe has for long been obsolete - caused by the high labour rates in garages.
These testings is however done by recon companies - like Pleiades - who sells recon & warranted Citroen hydraulic parts.
I wrote :
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"> ... connected, 1 wire attached for low pressure warning lamp & ... <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
- you're right - the safety valve has one more purpose : monitoring the system pressure.
At what exact pressure it opens for the suspension - seems to be somewhat depending on Citroenmodels & years - therefore the approx 90bar figure.
It does not do any limiting - it simply opens for the suspension when the system pressure is high enough to also feed the suspension. That's why the designation : safety/priority valve.
As you know the system pressure in any hydraulic Citroen is pendling around some 160bar - regulated by the regulator's valves - which means the system presure in fact vary between some 150-170bar - over the "click" sound time interval.
This pressure is constantly available in the brake & suspension feeds FROM the safety valve.
Please don't take these pressure values for exact terms - they are leading figures - which they also should be taken as in Haynes & other documentation.
There are absolute max & min figures which should only be adhered to if accurate pressure test equipment is connected to the system for testing components to spec's.
But such testing I believe has for long been obsolete - caused by the high labour rates in garages.
These testings is however done by recon companies - like Pleiades - who sells recon & warranted Citroen hydraulic parts.
Thinking more about this pedal pulsing, I didn't hear about any similar problems in CX, BX and GS. It is possible that these oscilations occur because of combination of worn brake (doser) valve and notorious spring between the pedal and the valve (older models didn't have it). Each of two slide valves inside the doser has a hole, so that the pressure on the underside of the slider is equal to the pressure in the brake circuit, to give the 'feel' on the pedal. If slide valves are worn, opening of the valve is probably somewhat uneven, so the pressure rises abruptly. I remember a BX I tested a long ago - its brakes were extremly sensitive, so each braking was a drama. Because of this, I think that slide valve can start to oscilate, since there is a spring between it and the pedal.
Just a theory.
Maybe it's not so bad - you have a kind of mechanical ABS.[:D][:D][:D]
Just a theory.
Maybe it's not so bad - you have a kind of mechanical ABS.[:D][:D][:D]
I'm a very late entrant to this discussion which interests me because we had the same problem on a 1993 Xantia. I'm also interested in Alexx's suggestion of the spring on the back of the pedal. I asked the question about this pulsing and it appeared on the old forum and the consensus was that the pulsing was caused by the spring (Well you do seem to have tried everything else don't you!) Someone on the board had replaced the spring (I think) with a small bolt and swore it worked - no more pulsing. I never tried it because my wife decided to get an HDi (interestingly, a mechanic I know says the HDi doesn't have the spring and though the brakes are otherwise the same as on "pre facelift Xantias" the brakes on the HDi are much more positive and inspire much more confidence than our old Xantia. By the way, our old Xantia had new discs and that made no difference, brakes also bled etc, no difference.
I may have kept a copy of the "removal of spring remedy" - I'll have a look.
I may have kept a copy of the "removal of spring remedy" - I'll have a look.
As Alexx wrote previously, authorised service in Osijek, Croatia replaced doseur on on my Xantia 1.8i from 1993 (ORGA no. 6050.) It happened on 9th of June this year. The reasons why I wanted to do that were: judder when applying brakes, fast sinking of car after parking (30 min.), often buzzing of HP & clicking of regulator (less then 10 seconds) when car was idle.
After replacing the doseur car behaved like new (subjective mark 'couse I'm the second owner) and I realy could notice the difference in driving, braking, no sinking when parked for two days (it stays parked more than one day just couple of times per year). Everything was just briliant
.
It was briliant for another 12 days.
Now I can fell judder when hard applying brakes together with droping of end for few inches (usually when braking on traffic lights) & sound similar to ticking of regulator (but with more often intervals) from rear of vehicle. This sound might be heard only with windows down and driving & braking in narrow street.
Front or rear of car (ther is no rule - sometimes is front but more often is end) sinks to 70 or 80% within the 1.5 hour. Other end sinks down after 4 or 5 hours. Car sinks totaly after 12 - 30 hours. I repeat one more time, when doseur was replaced car would stayed in normal position for days!
I'm preparing to do my first advanced DIY job in couple of days: cleaning the filters in LHM tank and bleed the brakes on all 4 weels. I hope this migh help me.
Previous topic initiated by Alan S maybe gives more light to this problem. I have noticed that HP on my Xantia is louder than on some BXs and Xantias.
Any ideas that might help? Thanks
P.S. sorry for language (it is not my mother tongue) 'couse it is late, I'm tired and Tuborg bottle is empty
!
After replacing the doseur car behaved like new (subjective mark 'couse I'm the second owner) and I realy could notice the difference in driving, braking, no sinking when parked for two days (it stays parked more than one day just couple of times per year). Everything was just briliant
.It was briliant for another 12 days.
Now I can fell judder when hard applying brakes together with droping of end for few inches (usually when braking on traffic lights) & sound similar to ticking of regulator (but with more often intervals) from rear of vehicle. This sound might be heard only with windows down and driving & braking in narrow street.
Front or rear of car (ther is no rule - sometimes is front but more often is end) sinks to 70 or 80% within the 1.5 hour. Other end sinks down after 4 or 5 hours. Car sinks totaly after 12 - 30 hours. I repeat one more time, when doseur was replaced car would stayed in normal position for days!
I'm preparing to do my first advanced DIY job in couple of days: cleaning the filters in LHM tank and bleed the brakes on all 4 weels. I hope this migh help me.
Previous topic initiated by Alan S maybe gives more light to this problem. I have noticed that HP on my Xantia is louder than on some BXs and Xantias.
Any ideas that might help? Thanks
P.S. sorry for language (it is not my mother tongue) 'couse it is late, I'm tired and Tuborg bottle is empty
!Found it (the brake pedal spring thing) It was in a reply by NiSK to a similar question
Quote:-
"2) the "silly spring" in the brake pedal arrangement, used to make the brakes feel more like a "normal" car's originated in the CX i believe, it's certainly fitted to all XM's but I didn't know it was found on the Xantia as well. There is a standard cure for this stupidity over here in Sweden - you just dismount the plastic connecting sleeve from the pedal to the brake distribution valve assembly (it's just pushed in place, in any case on the XM,) pull it apart, remove the spring and replace it with a nut that fits in the diamater of the sleeve. Replace the sleeve and Bob's your uncle.
Mind out the first time you try the brakes though! our you'll end up with a bunch of Ford Escorts in your rear! The modification also lowers the level of the brake pedal, so it gives a faster response time to braking"
And her's another reply from John W in Aus
"From JohnW,
Thanks for this information. I finally took the plunge and wriggled under the pedals of my Xantia. I can report that my 1995 Xantia has the same plastic device with a spring acting on a plunger between the pedal and the brake valve. I pulled out the spring and replaced it with a nut drilled to 10.5 mm ID, and with the outside ground a bit so it fitted where the spring went. The nut was about6-10 mm thick (just small enough to be able to get the plastic plunger device back into place behind the brake pedal).
The result? Huge improvement in brake "feel", much like I remember a DS feeling many years ago. The pedal is now hard after a short initial movement. Lovely and feels safer too.
Regards from Western Australia - just so you are reminded that this forum spreads far and wide!!
Cheers
JohnW
You can read the whole thread from about a year ago at
http://www.andyspares.com/discussionfor ... tia,brakes
Sorry it's such a long post but hope it is of use.
PhilW
Quote:-
"2) the "silly spring" in the brake pedal arrangement, used to make the brakes feel more like a "normal" car's originated in the CX i believe, it's certainly fitted to all XM's but I didn't know it was found on the Xantia as well. There is a standard cure for this stupidity over here in Sweden - you just dismount the plastic connecting sleeve from the pedal to the brake distribution valve assembly (it's just pushed in place, in any case on the XM,) pull it apart, remove the spring and replace it with a nut that fits in the diamater of the sleeve. Replace the sleeve and Bob's your uncle.
Mind out the first time you try the brakes though! our you'll end up with a bunch of Ford Escorts in your rear! The modification also lowers the level of the brake pedal, so it gives a faster response time to braking"
And her's another reply from John W in Aus
"From JohnW,
Thanks for this information. I finally took the plunge and wriggled under the pedals of my Xantia. I can report that my 1995 Xantia has the same plastic device with a spring acting on a plunger between the pedal and the brake valve. I pulled out the spring and replaced it with a nut drilled to 10.5 mm ID, and with the outside ground a bit so it fitted where the spring went. The nut was about6-10 mm thick (just small enough to be able to get the plastic plunger device back into place behind the brake pedal).
The result? Huge improvement in brake "feel", much like I remember a DS feeling many years ago. The pedal is now hard after a short initial movement. Lovely and feels safer too.
Regards from Western Australia - just so you are reminded that this forum spreads far and wide!!
Cheers
JohnW
You can read the whole thread from about a year ago at
http://www.andyspares.com/discussionfor ... tia,brakes
Sorry it's such a long post but hope it is of use.
PhilW
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norfolkmick
- Posts: 6
- Joined: 12 Jul 2003, 20:24
- Location: United Kingdom
- My Cars:
Akojic
I had my doseur replaced onmy BX last year and initially the car felt transformed and it seemed that all my problems had dissappeared. like you it returned to normal after a couple of weeks and to be honest the new valve made no difference at all.
When the valve was fitted the brakes would have had to be bled as all the brake pipes would have had to be removed. The normal sympton of air in the brakes seems to be that they don't release properly which seems to be one of the problems your car is not suffering from.
I know the frustrations of trying to find an elusive problem. My BX would suffer from low pressure when being driven and would put the warning light on. Eventually by chance I found the steering splitter relief valve had been wrongly assembled and the cure cost me nothing at all. On the way I'd overhauled another splitter (must take it to bits again and find where I went wrong), replaced the pump (all lovely for about 4 months) replaced the doseur, and changed the regulator for another as well as spending many hours trying to understand how it all worked.
Jeremy
I had my doseur replaced onmy BX last year and initially the car felt transformed and it seemed that all my problems had dissappeared. like you it returned to normal after a couple of weeks and to be honest the new valve made no difference at all.
When the valve was fitted the brakes would have had to be bled as all the brake pipes would have had to be removed. The normal sympton of air in the brakes seems to be that they don't release properly which seems to be one of the problems your car is not suffering from.
I know the frustrations of trying to find an elusive problem. My BX would suffer from low pressure when being driven and would put the warning light on. Eventually by chance I found the steering splitter relief valve had been wrongly assembled and the cure cost me nothing at all. On the way I'd overhauled another splitter (must take it to bits again and find where I went wrong), replaced the pump (all lovely for about 4 months) replaced the doseur, and changed the regulator for another as well as spending many hours trying to understand how it all worked.
Jeremy
Akojic, Id be very very suspect of changing any doseur valve. THis seems to be a common excuse for rear sinking, but its not the only reason. When was the LHM last changed or flushed?? I think the LHM gets 'thin' with life and can escape easier, changing LHM keeps everything up long, extra pressure doest as well.
As for the pulsing brake pedal, have you checked the LHM level?? I know its an obvious thing to check first (dont just trust the level guage either), but i had a Xantia come in with these problems (really really bad pulsing at any speed above 30) a litre of LHM later and the problem dissapeared (ut had NEVER been checked!!). Worth a look see?
As for the pulsing brake pedal, have you checked the LHM level?? I know its an obvious thing to check first (dont just trust the level guage either), but i had a Xantia come in with these problems (really really bad pulsing at any speed above 30) a litre of LHM later and the problem dissapeared (ut had NEVER been checked!!). Worth a look see?
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norfolkmick
- Posts: 6
- Joined: 12 Jul 2003, 20:24
- Location: United Kingdom
- My Cars:
Hi,
I've been and checked the bleed off (return pipe) from the brake valve (doseur valve). With the engine idling, and the pipe in a jar, it flows continuously, about half a litre in 3 or 4 minutes, more if I pump the brake peddle..... please tell me this is far to much... it looks like a nightmare to change, but who cares if it cures part of my trouble. Would a second hand valve normally be OK, or is there a repair kit... running out of money very quickly.
Thanks again,
Mick
I've been and checked the bleed off (return pipe) from the brake valve (doseur valve). With the engine idling, and the pipe in a jar, it flows continuously, about half a litre in 3 or 4 minutes, more if I pump the brake peddle..... please tell me this is far to much... it looks like a nightmare to change, but who cares if it cures part of my trouble. Would a second hand valve normally be OK, or is there a repair kit... running out of money very quickly.
Thanks again,
Mick
It's far too much. According to Citroen, acceptable "flow" from return pipes is only 3 ml/min for doser valve (and other hydraulic elements also). 1ml = 1 ccm = 1 cm3.
Of course, flow through return pipes when you press and release the pedal is normal (several ml per applying the brakes, depending how strong you press the pedal).
Of course, flow through return pipes when you press and release the pedal is normal (several ml per applying the brakes, depending how strong you press the pedal).
Correct.
Before fitting a new doser valve, I tried second hand, borrowed from the guy who sells Citroen second hand parts. It was older BX-type, with 2 slide valves and bleed nipple, but it fits (you have only to re-route pipe leading to rear brakes). Probably it had twice the mileage. And the result - ticking interval of the regulator reduced from about 10 to about 5 sec - it leaked about twice more. So I fitted the new one. It's fine since (6 years).
Before fitting a new doser valve, I tried second hand, borrowed from the guy who sells Citroen second hand parts. It was older BX-type, with 2 slide valves and bleed nipple, but it fits (you have only to re-route pipe leading to rear brakes). Probably it had twice the mileage. And the result - ticking interval of the regulator reduced from about 10 to about 5 sec - it leaked about twice more. So I fitted the new one. It's fine since (6 years).
Hi all, i'm new to the forum as you may have gathered!. OK a little about myself. I'm 30, live in Birmingham and work as a lawyer. Throughout my 20's i always had VW's and at present i'm selling my pride and joy, an Audi Coupe 2.2E (if anyone's interested). So why i hear you ask am i on a french car forum??, well the answer is simple!. I recently accepted a position in Leicester which means i have to commute 90 miles a day. Therefore i needed a car that would be cheap to insure, hopefully maintain and economical. So last sunday (6/7/03) after extensive research i bought myself an 'L' reg Xantia 1.9 SX TD. So far i really am impressed. It has 89.500 and drives wonderfully. So far i have changed the 2 front tyres and fitted my own radio using an autoleads facia adaptor. However i tried the steering controls (yes, i have a smart lead for my sony) and they dont work!, when i peeled off the steering wheel pad i noted that the pin connecter was not connected to anything!.
Anyway, the reason i took interest in this forum is because my car too suffers the same brake problem as described above as you might appreciate, coming from a VW, Audi background, i don't have the faintest!!!
Help!!
KUL3X[:(]
Anyway, the reason i took interest in this forum is because my car too suffers the same brake problem as described above as you might appreciate, coming from a VW, Audi background, i don't have the faintest!!!
Help!!
KUL3X[:(]
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norfolkmick
- Posts: 6
- Joined: 12 Jul 2003, 20:24
- Location: United Kingdom
- My Cars:
Pulsating brakes,
Firstly thanks to all those that gave me their valuable advice. My 1993 Xantia td had pulsing brakes, it dropped quickly and the regulator kept cutting in every 5 seconds.
I replaced just about every thing, regulator accumulator, front legs, level controls F/R, and the thing still did all of the above. I then bought a S/H brake valve (can't afford new, bloody car has eaten all my money) what a job, the most painful job I've done on the car so far, but it has cured the lot, I did the job by removing the valve from the doner car complete with the 4 h/pressure pipes attached, by removing the hydraulic reservoir, below and behind are the 4 pipe connectors, I undid these pipes and the return, after undoing the valve and pipe clips, pulled the lot out in a lump. I taped the replacement pipes together and treaded them back, bolted the valve in place and then reconnected the pipes.
I only have the use of one hand and this was the only way I could think of doing the job.
I like the idea of replacing the spring behind the peddle with a nut of the right size to get that old BX brake feel back again, when my hand and arm recover I'll do the modification.
Thank you all again from a relieved but sore.... Mick
PS I keep looking out at the car, after 3 hours it still hasn't dropped, fantastic..
Firstly thanks to all those that gave me their valuable advice. My 1993 Xantia td had pulsing brakes, it dropped quickly and the regulator kept cutting in every 5 seconds.
I replaced just about every thing, regulator accumulator, front legs, level controls F/R, and the thing still did all of the above. I then bought a S/H brake valve (can't afford new, bloody car has eaten all my money) what a job, the most painful job I've done on the car so far, but it has cured the lot, I did the job by removing the valve from the doner car complete with the 4 h/pressure pipes attached, by removing the hydraulic reservoir, below and behind are the 4 pipe connectors, I undid these pipes and the return, after undoing the valve and pipe clips, pulled the lot out in a lump. I taped the replacement pipes together and treaded them back, bolted the valve in place and then reconnected the pipes.
I only have the use of one hand and this was the only way I could think of doing the job.
I like the idea of replacing the spring behind the peddle with a nut of the right size to get that old BX brake feel back again, when my hand and arm recover I'll do the modification.
Thank you all again from a relieved but sore.... Mick
PS I keep looking out at the car, after 3 hours it still hasn't dropped, fantastic..