Loosing Pressure

[Peter.N.]

I have had an ongoing problem with pressure loss for a couple of years and although the car functions OK, I thought I ought to look into it. One of the two thick rubber pipes to to reservoir, the one that doesn't feed the pump, is returning a lot of fluid. I splits into two just below the reservoir, one part goes to the rack and the other to the distribution block next to the regulator, its this one which returns a full bore of fluid when the pump is operating. I assume that this is not normal, I have replaced the block with another secondhand one and the results are the same, do I have two faulty ones or am I missing something?

The symptoms are: the regulator cuts in every 5-10 seconds, the pressure is slow to come up in cold weather and if I leave it parked for more than a few minuets the brake pressure has gone.

The Haynes manual doesn't help at all, the Xantia one is no better, the only one that describes the system indetail is the CX one, and I loaned that to someone.......

Can anyone help?

Thanks. Peter.N.

[techmanagain]

While I'm busy racking my brains about your problem, don't feel insulted if I ask you if you have replaced the main accumulator recently? And is the steering operating normally when there is pressure in the system. There is obviously a leak somewhere. If it's in the steering rack, don't start checking your bank balance - I have a new one in among my spares! If it in the FDV (Flow Distribution Valve), I would be surprised as you say you have changed that already.

I'll go away and have another think.

[techmanagain]

As the pipe you have identified only connects with the Pressure Regulator (and its Valve) and the FDV, if you can dismiss the FDV, then you are left with the PRV or the Pressure Regulator as being the source of the leak-back. There are two possible reasons for this, one being the failure of the regulator itself - and this is not unknown - or its valve itself is leaking.
Have you at some time had reason to loosen the pressure relief valve bolt on the side of the pressure regulator and not re-tightened it sufficiently, or have you perhaps unscrewed the valve too far and managed to drop the ball out before you screwed the valve bolt back? I expect that we have all done this at some time., so you are not on your own!
I look forward to your findings.

[Peter.N.]

Hi techmanagain

I have already replaced : the pump (new) the regulator (secondhand) and accumulator (new) and also the distributer valve block (if thats what it is). There is some fluid returning from the rack but most of it is coming from the valve block, like full bore when you open the throttle. I replaced the rack on my previous car and don't particularly want to do it again! I have had this problem for 40k or more and it still keeps going so until now I have not done much about it. Another thing is that the regulator is hissing while its ticking over, if you blip the throttle it stops for a few seconds and then starts again, presumably when the pressure in the accumulator has dropped. It would seem that at tickover it cant replace the fluid fast enough. The steering is OK from the time you start the engine but the suspension is sometimes slow to rise and the low pressure warning light comes on. Any clues there?

Peter.N.

[techmanagain]

I am going to assume that the pump is 100%, also the main accumulator, so we are left with the pressure regulator ( into which the main accumulator is screwed) which is second-hand therefore must be suspect; and the pressure relief valve on the side of the pressure regulator -which is also part of a second-hand unit and so again a suspect.
But one point I have not established is whether there is air in the hydraulic system, which could possibly be the cause of the hissing in the regulator.
So back to that for a moment. Did you prime the pump when you fitted it by removing the supply pipe at the pump and filling the pump housing to the brim, allowing any air bubbles to escape before replacing the pipe at the pump. The engine should then be run with the relief valve open two turns, closed completely, opened two turns again and closed again, then that procedure once again repeated, the engine running all the time. There will even then be a short period before the car starts to rise, but that is normal.
You are sure that the ball is in the pressure relief valve?
If you are totally re-assured that the pressure regulator is satisfactory together with its relief valve, then surely you are looking at a faulty flow distribution valve (the distribution block mounted on the front of the engine) by a process of elimination - not so?
Here it is, Saturday night and not even Sunday, and I'm perhaps preaching to the converted!

I shall be away for a week from tomorrow - in Devon! - so a really urgent message can be got to me on 01392 259563.

[Peter.N.]

You'll be in Exeter then, wave as you go past! Right, to recap. The pump is new and I did bleed it but by filling the pipe from the reservoir end, which has always worked OK in the past. No, there is no air in the fluid, no leaks on inlet hose, the ball is present in the regulator as you can hear the oil flowing when you open the bleed screw, and with it open I get no pressure at all. I have changed the regulator and the distribution valve block but both with secondhand ones. What I really want to know is, is the ammount of fluid returning from the distribution block excessive i.e. 'full bore' If so I assume this unit is faulty.

Have a nice week in Devon, I hear they are forcasting snow! Pity, its been beautiful this week.

Peter.N.

[jorgy9]

Hi Peter,

I'm afraid very few people on this planet really know how much each hydraulic part on a Citroen is supposed to leak in normal conditions, and how nuch is "excessive" leaking. I'll ask a friend who's the only person that I can think of that perhaps knows. If you can write French, post to Activa Club at yahoo, there are a couple of really knowledgeable guys there.

In the meanwhile, how much are a new FDV and a new accumulator? I would have bought new ones from the onset, with these kind of parts -as I'm sure you know- there's no value in buying second-hand -they are likely to be bad as yours, or worse-...

I ll get back to you asap if I have an answer to FDV flow.

George

[jorgy9]

Peter, unfortunately the person I was thinking of, happens to be working 99% on Diravi cars, that don't use FDVs...sorry.

George

[Peter.N.]

Hi George

Thanks for the effort anyway. Strangly enough I have in the past been able to resolve problems with secondhand bits, but I know its a risk. The car has been running OK like this for about the last 40k so I am not desperate to cure it especially as the new bits would be over £200.00 and still might ot do the job. The CX manual explained in detail how the system worked with the now sadly missed exploded diagrams, but people don't seemed to be inclined to want to repair anything anymore.

Peter.N.

[jorgy9]

I guess you are aware that there's a service pack for the FDV. The tricky bit must be to reset the pressures on it though, and you would need a pressure gauge. Of course, "tricky" because I don't know how to do it, but it must be simple in reality...
Ah! and the FDV has a couple of little filters that need cleaning (normaly), like the LHM tank ones.

G