Definitely brake(doseur) valve??

harryb.48 · Post by **harryb.48** » 08 Sep 2004, 21:36

Hi Everyone,
having had the car(Xantia 1.8 estate ,8 valve) for about 5 weeks now and spent a lot of time ,and a few ££`s too ,I`ve finally come to the conclusion that my "pulsing pedal" problem is due to a failing brake valve - or is it??[?][?]
To recap on what I`ve done: replaced accumulator sphere; freed-up the rear height corrector and manual override mechanism and adjusted same to correct height;replaced both rear suspension spheres;performed cit-aerobics and bled both front and rear brakes more than once (and fitted a new battery and front droplinks as well - though these are unrelated to the braking problem!)
I haven`t yet replaced anti-sink sphere but doubt if this would be responsible for my problem.[?][?]
All discs and pads and run-out look ok but there is some evidence of rear discs not being "polished" by the pads but I put this down to height selector/corrector sticking and rear end generally having a mind of it`s own ,which may have influenced brake -line pressure - I`m talking of this going on for some time before I got the car - and of course the pulsing pedal may also have had more effect on the rear brakes.[?]
These are just assumptions based on my limited knowledge of the Citroen system! - Incidentally, the front spheres were just renewed before I bought the car.
There is a slight squelching sound from brake pedal ,though I`m not sure what is "Normal"
I haven`t checked the lhm return from the valve ,could anyone tell me which one it is?( I have checked the thin return but there are two - the second disappears behind the LHM tank)
I`m sorry this is such a long drawn- out posting - I just wanted to get all my thoughts down at once[:I]
The haynes manual says there is a repair kit available - has anyone any experience of this ,or should I just go for the new valve?[?]Price could come into the equation.
Also , I presume it`s not too difficult to remove/refit[?]- Being an 8-valve there is more room to work in I think. And is there anything I should look out for/or have available for the job[?]
Finally, there is a Rhythmic pounding noise (like a distant helicopter)which seems to be coming from under the battery and which I don`t recognise ,is this normal and am I being paranoid or is it another fault[?](I don`t know which answer I`d prefer!)
I will appreciate any advice and tips on any/all of the above.[:)][?]

madasafish · Post by **madasafish** » 09 Sep 2004, 00:32

"there is some evidence of rear discs not being "polished" by the pads "
Your rear calipers may be affected by the corrosion problem noted elsewhere on this site. I would suggest you attend /check that first as it "may" be the cause of your pedal problem. Others can no doubt comment.

oilyspanner · Post by **oilyspanner** » 09 Sep 2004, 00:36

yep, strip and clean those first, well known problem, often a no parts fix too, check BOL
Stewart

TheWorker · Post by **TheWorker** » 09 Sep 2004, 00:46

be very careful cracking off those caliper bolts, soak the thread from behind. i've had two bolts shear off on seperate jobs before, its not very nice when you spend half an hour drilling them out!!

harryb.48 · Post by **harryb.48** » 09 Sep 2004, 02:03

Thanks to the three of you so far - I will have a (much)closer look at those calipers soon. I think I had been ignoring "normal" problems and looking for the special Citroen ones.IE I had my head in the sand.[:I]Typically, I hadn`t read that particular posting,but I have now.[B)]
Any other tips will be appreciated[:D][:D]

harryb.48 · Post by **harryb.48** » 16 Sep 2004, 04:43

Sorry to come back with the same old problem,but another week has gone by and I still haven`t completely solved the pulsing pedal.( I might actually get to drive somewhere one of these days)
I`m pretty sure it`s not the rear calipers , all appears fine now - must have cured it with my many ministrations on the rear suspension and brakes(bleeding).
I also removed the spring from the plunger at the rear of the brake pedal - and I could still feel the pulsing ,but the frequency seemed higher which made me think again about the possibility it may still be warped discs although I thought I`d checked these properly.- I will look again.
This time I also got round to checking the LHM return from the brake control valve (2 pipes) and it was negligible - so I guess I can rule out the valve(??)
This has been and still is a very baffling fault ,no less so because it appeared to have disappeared only to come back again,and again.
My best description: It feels like the brakes grab and then partially release ,so I have to increase pressure as I near my stopping point or I could find myself overshooting.Removing that spring gave more control and I felt it less but I put it back in because it didn`t feel right(Too solid)
Perhaps this hint might help:I actually got in touch with the previous owner (on a different matter) and he said there was never any pulsing ,and since then it was kept by a repair garage who just put the two front spheres on and changed the oil!(Oh and it was MOT`d)
Perhaps the problem will just go away if I stop thinking about it*@!!&*

Stempy · Post by **Stempy** » 16 Sep 2004, 04:48

Could it possibly be a tired accumulator sphere?

CommY · Post by **CommY** » 16 Sep 2004, 04:49

Haven't read this thread fully but warped discs cause pulsing on the pedal. Plus the whirring sound is probably the warp on the disk catching the pad.
Just a thought.
What happens when you brake with the handbrake??

harryb.48 · Post by **harryb.48** » 16 Sep 2004, 05:00

Thnks for thoughts guys - Have changed the acc sphere recently.
The whirring sound is not connected to this fault and is when standing still (more a beating sound)
I am leaning towards the discs,but the frequency seems too low to me (I.E. the pulse covers more than one rev of any wheels)
I will recheck them thoroughly though as I`m running out of ideas!

harryb.48 · Post by **harryb.48** » 16 Sep 2004, 05:04

PS I noticed nothing when stopping with handbrake but was only travelling slowly - will try a bit faster next time

stephen burch · Post by **stephen burch** » 16 Sep 2004, 11:01

Harry..... You're learning fast aren't you. Isn't it amazing what necessity can do!

harryb.48 · Post by **harryb.48** » 16 Sep 2004, 17:31

Guess what? - yes, when I went for morning papers there was not a trace of the dreaded pulse!
I`m trying to think what I did last and it was just replacing the pedal spring and taking out the nylon bush (which conveniently fitted),and checking the LHM return flow , neither of which should have had any affect. - It was raining though.....
Anyway I do expect it to come back again,so maybe I`ll just change the brake pads for the fun of it ,even though they have 6-7 mm on fronts and 8-9mm on rears.
Thanks Stephen for that confidence booster,but I`d certainly prefer to be driving it than lying underneath it - taking necessary precautions of course!

AndersDK · Post by **AndersDK** » 16 Sep 2004, 18:04

Harry, try if any help here : Overhauling the brake valve

harryb.48 · Post by **harryb.48** » 17 Sep 2004, 01:11

Thanks again Anders,I may yet have to get at that valve.
I`m hoping it won`t be necessary ,but I`ll just bite the bullet if/when it comes to it.
The sinking I think might fall into "normal" parameters now - about 3cm or so all round?? And it doesn`t seem to hit the stops no matter how long it`s left - max 3 days so far.
I take it that the repair kit is readily available?
Here`s hoping that ,by some magic,it has been cured - but in all my experience of cars ,faults rarely disappear!