Flow distributor valve diagnosis

jonathan_dyane · Post by **jonathan_dyane** » 18 Sep 2004, 22:39

Hi Jeremy, the stop light does indeed go off.
I am pretty confident the brakes themselves are ok, the handbrake is excellent. When I got the car I replaced the discs and pads, thinking the poor brakes was due to the scabby discs, but this made no difference. (both front and back replaced.)
One front caliper was *slightly* sticky on the slider, but the mot showed only a slight imbalance (I kept an eye on the gauges!), and there is no sign of any pull to one side when braking. The pistons in the rear calipers were perfect.
Cheers,

oilyspanner · Post by **oilyspanner** » 19 Sep 2004, 01:12

I seem to have a very similar problem with my TZD(1993 ABS model too) poor power steering sometimes, brakes feel deader than previous Bxs, to date have replaced FDV, pump, new acc sphere,LHM a symptom I have noticed a couple of times is that the steering becomes very heavy immediately after heavy braking (involving ABS kicking in)
I intend to try hydraflush too. I have a spare FDV if you need it
Stewart

jeremy · Post by **jeremy** » 19 Sep 2004, 13:21

ABS uses a fair amount of high pressure LHM as the brakes cycle on and off. With a good pump this should be made up quickly, with a weak one it won't. However if the light is off there should be enough pressure even if the accumulator is charging.
I suppose its possible that the spring in the safety valve has gone soft allowing the light to go out early? I've never seen any reference to it here! How long does the light take to go out?
jeremy

oilyspanner · Post by **oilyspanner** » 19 Sep 2004, 15:05

Light extinguishes immediately and does not come on during running. I have replaced the HP pump with a known good one though its a possibility that the new one is tired too,
Stewart

jonathan_dyane · Post by **jonathan_dyane** » 20 Sep 2004, 00:20

Stewart, very interested to hear of your experiences, does indeed sound very similar to mine.
For your information, my ABS is now erratic ( I assume due to a dodgy front sensor cable), but now the ABS light is on the brakes feel just the same, except now obviously I can lock the wheels as the ABS doesn't come in...
I would be very interested in your spare FDV, where are you?
Will let you know what happens when the hydraincage goes in, hopefully tomorrow.
Cheers,

jonathan_dyane · Post by **jonathan_dyane** » 21 Sep 2004, 00:46

The plot thickens...
I took took off the LHM reservoir and gave it and the filters a good clean. After reinstalling and filling with the hydraincage the pump would not prime.
I tried for ages, including holding the pump supply pipe high up with a funnel full of fluid and still nothing. Looks like the pump ain't the best...
Next trip scrapyard for new pump. Fingers crossed

alexx · Post by **alexx** » 21 Sep 2004, 03:41

Did you slacken the pressure release screw on the regulator?
Strange feeling on the brake pedal could also be connected with ABS unit internally leaking, or air in rear brake circuit

jonathan_dyane · Post by **jonathan_dyane** » 22 Sep 2004, 01:42

I certainly did! With screw slackened and a funnel full of fluid wedged in the supply pipe and raised above height of pump still nothing happened.
I've been extremely busy today so haven't touched it, but i'll be going to the scrap yard in the morning, will report my findings later...
Cheers,

jeremy · Post by **jeremy** » 22 Sep 2004, 12:51

What's the condition of the hose from the reservoir to the pump? If its perished it may have become porous and because its subject to a depression it only allows air to be drawn in and LHM does not leak out. Air in the system will cause all manner of problems.
Anders suggests you replace the hose temporarily with a length of garden hose (clean of course) and see if it makes any difference.
jeremy

jonathan_dyane · Post by **jonathan_dyane** » 26 Sep 2004, 02:18

Well it's fixed, I *think*...
I've been holding off posting because I didn't want to tempt fate, but it has been a few days so I think I'm in the clear:
I described how I couldn't get the system to prime after replacing the LHM with hydraflush, well I went to a scrapyard and removed a hydraulic pump and FDV from a NA BX diesel in depressingly sound looking condition, and fitted the pump to mine. After filling the feed hose with the hydraflush and tightening the bleed after a couple of minutes with the engine running the stop lamp went out and the car rose beautifully.
The steering has been impecible ever since, and I think the brakes are improved too but it is hard to tell as while it was immobilised I was using the father's GSA, after which the best BX's brakes are going to be an anticlimax...
Hopefully the problem is cracked, but we shall see. Interestingly the original pump had a plastic body which I hadn't seen before and didn't particularly like the look of. Don't suppose it had a bearing on the situation.
Thanks for the advice everyone, I'll let you know how things go!

akojic · Post by **akojic** » 29 Sep 2004, 02:01

Am I wright saying that accumulator sphere is twisted to Presure regulator? FDV is black, square, thin, metal part fixed some 30 - 40 cm above the PR and accumulator sphere, is it? My car is Xantia 1.8i from 1993 (ORGA 6050) - ordinary hydropneumatic system. And what is security valve in that system and where it might be found? I'd like someone to write couple of sentences about their purpose in the system. Thanks

AndersDK · Post by **AndersDK** » 29 Sep 2004, 02:17

akojic -
The best technical description in popular terms on the various Citroen hydraulic systems is found here :
http://www.tramontana.co.hu/citroen/guide.html
Click the .pdf file document link, then choose to save the document on your HD, once Acrobat reader has finished loading the document. It's only approx 0.7Mb - wont take long to download.

akojic · Post by **akojic** » 30 Sep 2004, 01:04

Yeah, I've read suspension part and admit that still not sure about FDV and security valve in early Xantia. PR is part onto which accumulator is twisted!