Hi, My '93 Xantia TDSX has just started to have a pulsating brake peddle. The car has a new HP pump and I recently replaced the accumalator sphere and after that it has gone worse.It was only the odd occasion that it did it before.
It pulsates more when the car is stopped at traffic lights or wherever. The ABS light does as it should on start up and doesn't light up even when pulsating starts when moving.
If there is air in the system could this cause the problem? If so would bleeding it solve the problem? The ABS is a seperate system so this shouldn't cause the problem especially as it still does it at standstill.
Why do citroens do it? Just replaced the acc. sphere,Driveshaft gaiter, Radiator and exhaust pipe to the rear box, now this !!!!
Going away tommorrow dinner time, Have to bleed the frickin brakes I guess, watch this space, bet the damn nipples brake on me....
Paul
Dredded Xantia Pulsating Brake peddle.
Moderator: RichardW
Paul, check this topic, maybe it will be of some help
http://www.andyspares.com/discussionfor ... IC_ID=2926
http://www.andyspares.com/discussionfor ... IC_ID=2926
A new twist to the tale.
The brake pedal now seems to pulsate at random, and when driving the steering wheel has a twitch, as though it gets a little pressure 'boost' from the accumalator.[?]
I have noticed that when I stopped the car and turned the engine off, I put my foot onto the brake peddle and the pulsating was still their, wierd or what.
I have bled the brakes and all the bleed nipples turned okay (amazing). Is the Citaerobics a case of moving the hieght lever backwards and forwards for several goes???
Cheers
Paul
The brake pedal now seems to pulsate at random, and when driving the steering wheel has a twitch, as though it gets a little pressure 'boost' from the accumalator.[?]
I have noticed that when I stopped the car and turned the engine off, I put my foot onto the brake peddle and the pulsating was still their, wierd or what.
I have bled the brakes and all the bleed nipples turned okay (amazing). Is the Citaerobics a case of moving the hieght lever backwards and forwards for several goes???
Cheers
Paul
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Is the Citaerobics a case of moving the hieght lever backwards and forwards for several goes???
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote"> Yes ! - allow due time for height to settle fully on each setting.
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">when I stopped the car and turned the engine off, I put my foot onto the brake peddle and the pulsating was still their<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">- because your accumulator sphere still has working pressure left. The symptoms has nothing to do with the engine (& pump) running or not.
It's known that air in the brake circuits causes brake peddle pulsating.
Before doing anything else dramatic - ensure the system is 100% air vented.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote"> Yes ! - allow due time for height to settle fully on each setting.
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">when I stopped the car and turned the engine off, I put my foot onto the brake peddle and the pulsating was still their<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">- because your accumulator sphere still has working pressure left. The symptoms has nothing to do with the engine (& pump) running or not.
It's known that air in the brake circuits causes brake peddle pulsating.
Before doing anything else dramatic - ensure the system is 100% air vented.
Paul -
Closing in on the brake doseur (pedal) valve then - right ? [B)]
Not unlikely on a '93.
Other postings here seems this may well be the terminal solution.
This spring I allmost despaired when my '89 BX was due for MOT.
I ended up renewing ALL wear-bits on the rear :
Wheel bearings.
Rear cylinders.
Rear arm bearings.
Brakes & piping.
Last autumn the front subframe & Octopus were replaced ....
You know what's in your driveway - you never know when aquiring another s/h car ....
The only car cheaper/simpler to repair - I ever owned - was a '77 GM/Opel Kadett 1.0 (Vauxhall Chevette). But this crumpled away by the rust devil.
Closing in on the brake doseur (pedal) valve then - right ? [B)]
Not unlikely on a '93.
Other postings here seems this may well be the terminal solution.
This spring I allmost despaired when my '89 BX was due for MOT.
I ended up renewing ALL wear-bits on the rear :
Wheel bearings.
Rear cylinders.
Rear arm bearings.
Brakes & piping.
Last autumn the front subframe & Octopus were replaced ....
You know what's in your driveway - you never know when aquiring another s/h car ....
The only car cheaper/simpler to repair - I ever owned - was a '77 GM/Opel Kadett 1.0 (Vauxhall Chevette). But this crumpled away by the rust devil.
-
Dave Burns
- Posts: 1915
- Joined: 14 May 2001, 05:30
- Location: United Kingdom
- My Cars:
- x 2
I'd be inclined to try a fresh flow distributor, for two reasons, first its much easier to get at so that means its going to be much quicker to change, and two, you say you now have interferance with the steering, difficult to see how the brake valve could affect steering to a large extent (is this only while braking, or does it happen at any time) but the FDV can and does play tricks with the steering, in fact they are famous for it.
Dave
Dave
I agree with all thats been said. Is the new accumulator sphere ok? Whats your ticking speed? Does it retain pressure properly?
the warning light should help but unfortunately doesn't due to its interconnection with the oil pressure light (on BX certainly)
My BX will rise while I fill it with fuel with the engine stopped and similarily the car will raise itself when I get back in after a couple of minutes.
It has been known for replacement spheres to be defective and a couple of years ago I was told I had purchased one. (I put it like that as I don't trust the person who told me.)
Jeremy
the warning light should help but unfortunately doesn't due to its interconnection with the oil pressure light (on BX certainly)
My BX will rise while I fill it with fuel with the engine stopped and similarily the car will raise itself when I get back in after a couple of minutes.
It has been known for replacement spheres to be defective and a couple of years ago I was told I had purchased one. (I put it like that as I don't trust the person who told me.)
Jeremy
As DIY'er you often lack new parts for a quick replacement check. I usually use this method to check the accumulator sphere :
Take any known good sphere - i.e. one of your front strut spheres - and replace with the acc. sphere - fit the acc sphere on the front strut if you plan to raise the suspension during this test [:0][:p][:D][;)]
If the regulator ticking now calms down - the acc sphere removed is dodgy.
If the ticking interval only gets a bit slower - large internal leakage exists in the system.
You may raise the suspension - and do the common suspension sphere test on the corner fitted with the acc sphere - the acc sphere behaves exactly like a suspension sphere in this test.
The damper valve in the suspension sphere has no consequence for acc sphere testing - the pump/regulator pumping is slower than suspension movements damped.
NOTE : Do NOT drive the car with acc sphere fitted as suspension unit [:0][}:)][:o)][:(]
Take any known good sphere - i.e. one of your front strut spheres - and replace with the acc. sphere - fit the acc sphere on the front strut if you plan to raise the suspension during this test [:0][:p][:D][;)]
If the regulator ticking now calms down - the acc sphere removed is dodgy.
If the ticking interval only gets a bit slower - large internal leakage exists in the system.
You may raise the suspension - and do the common suspension sphere test on the corner fitted with the acc sphere - the acc sphere behaves exactly like a suspension sphere in this test.
The damper valve in the suspension sphere has no consequence for acc sphere testing - the pump/regulator pumping is slower than suspension movements damped.
NOTE : Do NOT drive the car with acc sphere fitted as suspension unit [:0][}:)][:o)][:(]
Hi, the ticking from the accumalator is quite rapide really, about every 4-5 seconds and the car drops down quickly too once the engine is off. I noticed that when doing the citrobics that the front end dropped down very quickly and when I had the footbrake on that the rear dropped with the 'tommy gun' pulsating. So I wondered if the rear brakes/suspension pipes may be clogged perhaps?
I also seem to think that the problem has worsend since I had the car up on axle stands to change the drive shaft gaiter!
A thought :- could the system go out of sinc and go unbalanced, therefore needing to be ballanced again in some way or form??
Paul.
I also seem to think that the problem has worsend since I had the car up on axle stands to change the drive shaft gaiter!
A thought :- could the system go out of sinc and go unbalanced, therefore needing to be ballanced again in some way or form??
Paul.
I think the more rapid sinking is of great significance. The thing is designed to produce a delay by means of fine orifices etc and cant simply let the car drop quicker by means of wear clogging an so on.
So what can make the car drop quicker - I think air / gas is the culprit. Air can only get in on the input side of the pump - so this must be in the pipe between the reservoir and the pump or perhaps some damage to the plastic filters and ducting in the reservoir.
gas could come from a ruptured sphere. Normal leakage seems to be expelled when the car rises and falls but a ruptured one would release a very large amount of gas at one go which might cause havoc but would be finite and once dispersed wouldn't return.
I find that when I use the recirculating valve on the regulator to bleed the system I can see loads of fine bubbles in the reservoir if I look through the filler cap. I would have thought that if air was getting into the pump feed you would see bubbles when at least the valve was open and probably all the time.
jeremy
So what can make the car drop quicker - I think air / gas is the culprit. Air can only get in on the input side of the pump - so this must be in the pipe between the reservoir and the pump or perhaps some damage to the plastic filters and ducting in the reservoir.
gas could come from a ruptured sphere. Normal leakage seems to be expelled when the car rises and falls but a ruptured one would release a very large amount of gas at one go which might cause havoc but would be finite and once dispersed wouldn't return.
I find that when I use the recirculating valve on the regulator to bleed the system I can see loads of fine bubbles in the reservoir if I look through the filler cap. I would have thought that if air was getting into the pump feed you would see bubbles when at least the valve was open and probably all the time.
jeremy
Hi guys (n gals),
I have spoken to a citroen guru and his opinion is.....The brake dosier valve it the problem, once it gets 'hot' after a few miles traveling, it starts to expand because of heat from the engine and use, causing the casing and gubbins to allow fluid to bypass the system and return to the resevior, this is causing the sensation of a pulsating brake pedal.
SO, guess whats happening this weekend, Yep, new doseur valve to be fitted. Cost £? cost to knuckles ????????????
Anyway here goes....will keep you informed.
Paul
I have spoken to a citroen guru and his opinion is.....The brake dosier valve it the problem, once it gets 'hot' after a few miles traveling, it starts to expand because of heat from the engine and use, causing the casing and gubbins to allow fluid to bypass the system and return to the resevior, this is causing the sensation of a pulsating brake pedal.
SO, guess whats happening this weekend, Yep, new doseur valve to be fitted. Cost £? cost to knuckles ????????????
Anyway here goes....will keep you informed.
Paul
Well, it's not cheap, it costed me about 120 EUR + labour, 6 years ago, on BX. Valve is the same (or almost the same - maybe slide valve diameter is different) for Xantia, but the price is even higher. Check overflow from return pipes before changing the valve, maybe something else is the problem (although I strongly believe it's the valve), it will take only 5 minutes.