Frequent clicking/ticking

jpeder · Post by **jpeder** » 24 Sep 2002, 02:46

Hello all
I've had a Xantia for a year now. When I first bought it the ticking didn't occur too often. The frequency has gone up though, which prompted me to replace the accumulator sphere. I also changed the suspension spheres because the ride was getting harder and breaking had a slow oscillation to it. Both symptoms were removed by the latter replacement but the ticking is still bad.
From investigating the BX Homepage (specifiacally this article on BX suspention diagnostics) and the disussions here it seems the next step is to test the return flow from the regulator and PAS valve, etc. I understand the procedure but with all the different terminology in Haynes and at garages I've become quite confused. I can identify the HP pump, and the accumulator sphere but that's about it. I've had the "accumulator block" changed because it was leaking (succes) which I assume is the contraption the accu sphere is mounted on. (Q1: does it have other names?) From what I can make of Haynes the regulator is mounted to the accu. block (Q2: is that correct?) If so Q3 is there an easy way of identifying the reservoir end (easier than pulling bits out of the engine)? Q4: where is the PAS servo control valve located? Q5: which bit is the PAS flow divider? Q6: are there some manuals or web-pages that show how the hydraulic system is hooked up, what components it has and how they look?
Sorry if these questions are redundant or basic.
I don't have much engine grease in my veins yet <img src=icon_smile_evil.gif border=0 align=middle>.
Cheers, JP.

Dave Burns · Post by **Dave Burns** » 24 Sep 2002, 03:39

Accumulator sphere is screwed onto the regulator.
What do you mean by "reservoir end", if acc./reg. assembly then its the sphere, this is where the reserve of high pressure oil is stored.
Power steering pinion valve is on the steering rack.
Depending on the year of car it may or may not have a flow divider, what year is it.
Dave

jpeder · Post by **jpeder** » 24 Sep 2002, 16:13

Dave,
I take it then that "acc. block" is another name for the regulator!?
What I mean is what I understand from this article to be the return flow tube coming out of the regulator/PAS valve to the LHM reservoir. How do I identify the return flow tubes from these two devices?
Sorry, by steering rack are you refering to the assembly containing the ignition switch?
It's a Non-hydractive 1.9TD SX '94 L reg.
Are there no manuals/web-pages that show and explain how these parts are inter-connected and where they are located?
Thanks, JP

Post by **RichardW** » 24 Sep 2002, 16:52

(Q1: does it have other names?)
It's usually known as the pressure regulator - 'cos that's what it does!
(Q2: is that correct?)
See above - they're one and the same
Q3 is there an easy way of identifying the reservoir end
The reservoir is the black tank at the rear RH sidew of the engine bay, with the level indicator on top and the cap marked 'LHM' All but one of the hoses connected to it are return hoses - the largest one that leads direct to the pump is the suction hose.
Q4: where is the PAS servo control valve located?
As Dave says, on the steering rack. This is the part that actually makes the car steer - located across the rear of the front subframe under the car. The servo control is integral with the pinoin, where the steering column is joined onto the steering rack.
Q5: which bit is the PAS flow divider?
As yours is 94L, it will have one of these - it is mounted very close to the pressure regulator, and has pipes running from the HP pump, and to the pressure regulator and steering rack
Q6: are there some manuals or web-pages that show how the hydraulic system is hooked up, what components it has and how they look?
The web site you mentioned is pretty good, and applicable to Xantia as to BX. The only difference is the location of the LHM reservoir, and the pipe locations connected to it. Just trace the rubber hoses back from the components you are interested in. If you take off the pump return hose though, BEWARE! The pump runs all the time, and if nothing is using any fluid, it cycles straight back to the reservoir. The pump can empty the tank in around 90 seconds, so a lot of fluid will come out if you take this pipe off with the engine running!
My guess is that your frequent ticking will turn out to be the brake valve (located on the bulkhead in front of the brake pedal, where the master cylinder normally is). This wears internally and leaks pressure from the rear suspension (does your car drop its rear end pretty quickly after switch off?), causing the frequent ticking. A very common fault on higher mileage Citroens. Could also be a leak from a front strut, or just that you've fitted a duff accumulator (it does happen!)
HTH
Richard

Dave Burns · Post by **Dave Burns** » 25 Sep 2002, 00:24

I think you will find that a 94L will not have a flow divider, to find out, look at the hydraulic pump, if there are two small steel pipes coming from the top of the pump, there will not be a flow divider.
Have a look, or it could get confusing.
Dave

jpeder · Post by **jpeder** » 25 Sep 2002, 01:12

Richard,
Thanks for the troubleshooting, here's some feedback though.
Even if the acc. had been replaced (by a Citröen garage how even claimed to test the old one for rechargeability) with another flat one, this shouldn't have any (or much) effect on the ticking when the car is stationary and nothing is being operated since. Little spare pressure is needed then, right!? The regulator ("acc. block") is mint so it shouln't be leaking through and neither the back nor the front sinks noticeably within half an hour. The back is a bit mushy and the front quite springy, but even so when the pump is on.
In conclusion the system doesn't seem to leak much when the pump is off. There is, however a distinct hissing from the inside steering assembly when turned. This is why I wanted to proceed with test 3 and on.
From what you are saying the Xantia hydraulics are the same or very similar to that described for the BX here? If they are, too aid me in tracing them <img src=icon_smile_dissapprove.gif border=0 align=middle>, how do the LHM return hoses from the reg., PAS valve, FD & brake valve look?
Cheers, JP.
BTW, which models don't have FD's, where can I learn about these things?

jpeder · Post by **jpeder** » 25 Sep 2002, 01:31

Sorry Dave,
Didn't see your RE. It's a bit dark out there now but I can only see two hoses on the immediate top of the HPP, a larger (suction) hose and a smaller (pressure) pipe. That means there is an FD somewhere, right?
Do you know how the FD improves the system?
Thanks, JP.

Post by **Jon** » 25 Sep 2002, 01:51

Yeah,thats right, if you have one rubber and one metal hose from the pump, then you've got a flow valve (ie a 6 piston pump), 2 metal, one rubber means that the car has a 6 + 2 pump that does without a flow valve.
The flow valve simply flows LHM fluid left to right for power steering, its not likely to be implicated with your "clicking". Theres very little that can go wrong with the flow valve apart from the small internal filters becoming blocked, if this is the caes then the steering is generally "heavy" particulary in one direction.
<img src=icon_smile_sad.gif border=0 align=middle>
Jon Wood
IT Supervisor
GSF t/as Andyspares

Dave Burns · Post by **Dave Burns** » 25 Sep 2002, 03:04

Hmmm, a bit strange this, my previous 19D Xantia was a 94L and had anti-sink, have read somewhere that this was also accompanied by the 6+2 pump and discontinuance of the F/D since with anti sink the high output 6 piston pump was no longer required for the suspension, the 2 pistons in the 6+2 pump being for the suspension and brakes, the 6 pistons for the steering.
A youth at my place of work has a 93L and it drops like a brick, its on the deck in less than ten minutes.
JP, does your car have anti sink, look for a sphere roughly center of car between the rear wheels.
The folw divider has 5 (I think) pipes going to it, should be easey to find between pump and regulator piping.
Dave
p.s hissing from steering inside car is normal, its just the sound of oil being forced through a smaller apperture in the valve as the steering is turned.
A flat accumulator sphere will cause the regulator to cut in and out rapidly, wether car is being driven or is stationary, reason, brake valve, height correctors, security valve and even regulator all leak internally.
This means the small amount of pressure that can be stored by a flat or near flat sphere is soon used up by the internal leakage, resulting in the regulator cutting in again, and so it goes on....

jpeder · Post by **jpeder** » 25 Sep 2002, 15:39

Dave,
I've had a look under the rear and there is no sphere between the height corrector and the exhaust. So I guess I've got a HPP6, FD and no anti-sink?
It doesn't sound right that the 93L you mentioned sinks that fast. As mentioned, I have brand spanking suspension spheres.
What you are saying is that a small spare pressure in the acc. will be used up quickly by leak-through in various components. This is in agreeance with the above mentioned article. From what I understood though, the leak-through of any of these components shouldn't be significant, so that when the car is stationary even a small spare pressure should last long.
Cheer, JP.

Dave Burns · Post by **Dave Burns** » 27 Sep 2002, 04:03

JP, just been mashing the keys on the complicator and it seems the cut in and cut out pressure of the regulator, a difference of 25 bar (367.5 psi) requires only 20cc of oil.
Sphere volume 400cc
Sphere gas pressure 62 bar (911.4 psi)
Regulator cuts in at 145 bar (2131.5 psi)
Regulator cuts out at 170 bar (2499 psi)
1 bar = 14.7 psi (at sea level)
Boyles law states that if a volume of a gas is halved by compression the pressure of it will be doubled.
So for example, if 200cc of LHM is pumped into the sphere the pressure will rise to 124 bar (1822.8 psi)
I calculate that when the regulator cuts out the gas volume will have been compressed by the oil down to 163cc @ 170 bar
And that it will expand to 183cc before the regulator cuts back in at 145 bar.
Does anyone concur, or have I been supping at the bathwater saloon again.
Dave

Post by **RichardW** » 27 Sep 2002, 13:52

Dave,
Nearly, but not quite.....
1 bar is actually 14.5 psi - 1 atmosphere (ie the 'normal' pressure at sea level) is 14.7 psi - 1.013 bar. To apply Boyle's law you need to convert to absolute pressure (ie the pressure you would read on a gauge relative to atmospheric - gauage pressure - plus the atmospheric pressure) ie 62bar gauge (barg) is 63.013 bar absolute (bara).
Now, by my calculations this results in a gas volume of 147.3cc @ 170 barg and 172.6 cc @ 145 barg, so a difference of 25.3 cc.
If you now consider a sphere at 31 barg (ie half pressure) you find 75cc @ 170 and 88cc @ 145 - only 13cc different, so tick-interval will have doubled, but repressuring time will have halved.
Of course this assumes an ideal gas, and compressibility of 1. Fortunately Nitrogen does a pretty good impression of this, otherwise we'd be all at sea....!
Richard

Dave Burns · Post by **Dave Burns** » 29 Sep 2002, 06:26

Thank's Richard, I bow to your superior knowledge, been trying to replacate my earlier calculation's, can't remember just what I did wrong.
Got the correct formula and agree with your figures.
The point of the exercise was to show just how little oil is actually used between regulator cycles, even with a good sphere, 25cc isn't much at all and a system that only wastes that quantity in 30 seconds is in very good condition.
Dave