Still sinking/still have pulsing pedal

harryb.48 · Post by **harryb.48** » 17 Aug 2004, 04:36

Since buying my Xantia I`ve had a few problems,some are fixed thanks to this forum,but after replacing accumulator sphere and bleeding rear brakes I still have pulsating pedal but to a lesser extent - this feels more like hydraulics as the brake grabs and releases in the space of ,say,6 or 7 roadwheel revolutions and not on each rev as you would expect with a mechanical fault.I am now a bit confused [?]
as to what it might be despite being given a few pointers ( Doseur valve, or perhaps leaking nitrogen into system etc )- any more ideas out there?
Also I still have sinking overnight almost to rock bottom (rear only)
and the rear normal ride height is more than 3 cm too low.
Does this mean I have to change the anti-sink valve or do I change the sphere first?And the height corrector ,anything I can do or must I take it to a garage?
I`ve read so much stuff about the suspension that my head`s reeling![:(]

stephen burch · Post by **stephen burch** » 17 Aug 2004, 12:01

If you start the car, put it in normal ride height then take off the return pipes on the LHM tank to see if there is an internal leak.(it's best to prise the clips off beforehand). If there is then you will get an increased flow on one compared to the others. On my Activa the first or second pipe nearest the bulkhead leads to the rear anti-sink valve and if you have more than a trickle then suspect the valve.
I didn't have a pulsing pedal with my car but the back did keep sinking and sometimes with a jolt. I replaced the anti-sink sphere but still had the problem. See my post,"Antisink valve" for fitment clarification.

harryb.48 · Post by **harryb.48** » 17 Aug 2004, 16:16

Thanks Stephen,I will look at the return pipes(It`ll have to be tomorrow now)
I had read about your problems and was hoping I wouldn`t have the same hassle you had with that valve![:(]
If it is the valve -where best to buy it ? And is it expensive?I know you got yours online but it should be available locally?.(I have only had the car 2 weeks but already know how expensive Citroen can be!)Perhaps I should just bite the bullet and take it to a garage but I don`t like to give up trying myself.[B)]
I really don`t know if the brake problem is in the same area - I guess it will be a process of elimination.
Many thanks for now.
Harry

AndyP · Post by **AndyP** » 18 Aug 2004, 16:54

Have (or had) pretty much the same problem until last night. I replaced both the rear spheres - the N/S one seemed OK but the O/S one was fizzing as I took it off and all the fluid that drained out had a head on it ! So I guess that's a total sphere failure ! Think I still need to do the anti-sink sphere but that can wait a little.
Incidentally, I knocked up a sphere removal tool along the lines of the threaded rod and a lump of angle iron and it worked a treat (I'd already broken two strap wrenches and bent an oil filter chain wrench becuase the buggers were so tight). So if anyone in the mid Essex-ish area wants to come and borrow it then they're welcome. I may even give a bit of advice on it's use (laughing and pointing etc [:D] )

stephen burch · Post by **stephen burch** » 19 Aug 2004, 02:43

Harry..... The Citroen part number for the valve I bought is 5293.01. Check this with your dealer to see if it's right for your car, then go for the cheaper option.
As with any hydraulic fluid problem it's easier to check the condition of fluid and filters first.
The rear ride height may be due to a mucky height corrector. Check condition of bars and linkages etc and make sure main clamp hasn't slipped.

harryb.48 · Post by **harryb.48** » 19 Aug 2004, 18:32

Thanks for info and suggestions guys.I have checked LHM return pipes - all seem to be the same as far as I could tell - just a trickle.
Having digested all the information I think the most logical step is to replace the rear spheres - if the front ones were shot then the rears can`t be too far behind - literally! (Anders...agree with this?) After all the car is 8 years old and I don`t think they`ve been done before .Incidentally,it has 70000 miles on the clock which is not too bad.
After that I will check the ride height/sinking and of course the brakes ,which have improved with each minor action taken.I will also
look closer at the height corrector in the meantime.
That will take care of my meagre pocket money for the next couple of weeks [:(] but I will keep you up to date with my progress - or lack of it!
Please let me know if anyone thinks its not the way to go.

alexx · Post by **alexx** » 19 Aug 2004, 19:52

My rear spheres were after 6 years at 7-8 bar, while front were only 5 bar down from the original pressure. The car has done 57.000 km.
I think it's possible that you, in fact, feel variations of the pressure in rear suspension on the pedal, if the spheres are flat, because in that case these variations will be very high. Is the frequency of these pulses in any connection with the speed and condition of the road?
Condition of suspension spheres can be estimated by bouncing the car and "measuring" its eigen frequency. It is about 0.8 cycles/sec with new spheres, and rising as the spheres lose nitrogen. In my case, it was around 1.4 cy/s (10 cycles took about 7s), suspension was quite hard and rear end was bouncing on bigger bumps. Anyway, there was no pulsing, but since there was lots of air in rear brake circuit (as I described in other post), it wasn't to be expected.

harryb.48 · Post by **harryb.48** » 20 Aug 2004, 00:27

Alexx,
You could be onto something when you say the feedback on the pedal is through the rear suspension; it is difficult to prove but in theory it sounds feasible and I will look out for it on the road.
Thanks[:)]