
@MatPL, you are saying, that you changed a couple of pumps, but have you tried to overhaul them before installing back into the car?
BR
Martin
That's what I meant about the Venturi effect. I will do a return line on the new hoses as now I have silicone tubing not working well with LHM.white exec wrote: 08 Jan 2021, 19:37 It is theoretically possible that a fast-flow pipe can create lower pressure sonewhere along its length (a Venturi effect?) if there is a restriction somewhere.
What you might be able to do is gently restrict the flow from this return pipe at the reservoir, and see whether the pressure in the pipe (which will be higher is you move the steering wheel) is enough for a leak to be seen/found. That leak will probably be the source of air ingress.
I have already tried with the cable mounted in this way. The microbubbles continue to flow to the pump from the LHM reservoir.lcwin wrote: 09 Jan 2021, 15:09 Matpl try this, You leave the car depressurise for a day to clear the bubbles . Get a thick Clear PU hose with internal diameter of the intake connector of the hydraulic pump . It must be nice tight fit without need to use any fasterner. The other end of the hose you directly insert into the LHM container without need to go into the filter but make sure its way below the level of the LHM oil.
I checked each pump for the expenditure before installation. 1 wheel rotation per suspension gave about 1.2 ml of LHM, and 3.5 ml of LHM for power steering. As described by Citroen. The seals were replaced every time. In May I was able to buy a brand new Citroen LHM pump and the result was the same.ksanturion10 wrote: 10 Jan 2021, 18:45 @MatPL, you are saying, that you changed a couple of pumps, but have you tried to overhaul them before installing back into the car?
The car's speed sensor gives information to the HA computer. The faster we go, the easier it is to put the suspension into sport mode to make it safer and it's normal and in line with Citroen's idea. In my case, when driving faster, the suspension selects bumps better. Driving at low speed with lots of twists and turns, the driving experience is rough and unpleasant.ksanturion10 wrote: 11 Jan 2021, 18:10 Mine is Hydro-Pneumatic, non Hydractive -> analog system. My engineering sense is telling me, that the suspension should harden at higher engine RPM, so it should be somehow flow depended. I don't have suspension ECU, that can query the speed of the vehicle, so I think it should rely purely onto the flow from the pump -> if ofcource the system is designed to harden in this way. So maybe, this is the normal situation and for the HA system, not sure.
I don't believe, that the bubbles can affect the system so much. Is there a way you can check if they are drawn into the high pressure circle after the conjecteur? To me this is highly unlikely as Icwin said, but who knows.
I have already adjusted the height 100 times. I tried to ride lower and higher. Unfortunately, the feeling of roughness is the same, but too high it becomes unstable when accelerating hard. With a lower setting it feels softer, but it can hit the ground too often.Hell Razor5543 wrote: 11 Jan 2021, 18:25 Something that can definitely affect the ride is if the suspension ride height is set wrong (I don't mean the control lever in the car; rather, if the front/rear is riding too high/low). On my basic spec Xantia (with six spheres) the front was riding too high, and she felt 'skittish'. Once this was corrected the ride felt much more stable.
I had the spheres checked this Saturday weekend.white exec wrote: 11 Jan 2021, 19:45 Looking at those two videos, Mat, of you pressing down on the FF and RR of the car, I would say that the suspension looks much too soft - especially for a high-BHP XM - with the body going down far too easily, and by too great an amount.
Are sphere gas pressures and damping apertures all correct, for not just corner spheres, but for centre ones as well?
Note that the damping for the centre (Soft mode) spheres is in the suspension regulators (where the EVs are).
Are your regulators the originals for the car, or did you fit late-Xantia type?
If Xantia-type, did you transfer the original XM dampers into the replacement regulators?
Is anything else non-standard?
I cannot agree with that because a few times this car has experienced a magical ride on a really horrible and rough road. I just got in in the morning and it rode perfectly for about 5km. Recently I was driving a C5 MK1 still on the original oil and spheres. I crossed the railroad crossing like a dream. I had to go back and try again because I didn't believe it. My Xm is shaking and creaking on the same railroad crossing despite good pressure in the spheres and new LHM oil. It is unfair!white exec wrote: 11 Jan 2021, 19:45 Harshness over sudden lateral ridges at low speeds is normal on these cars, unfortunately. It is the only situation where the HA suspension is less than good.
The air into a closed hydraulic circuit always tends to go up, opposite to earth's gravitational force, so I don't really believe, that the pump can push it into the conjecteur tube and into the main HP circuits. It will rather escape trough the pump before reaching the conjecteur. But you are right, about the down sides of air present in hydraulic circuits, when it comes to compression.MatPL wrote: 11 Jan 2021, 20:12 If the LHM oil has microbubbles in the hydraulic hoses and in the actuator, to do the work, it must first compress the air in the LHM and then press the diaphragm or perform work, etc. I think that on short bumps the oil moves too slowly in the tubes to compress the diaphragm which results in a rough lagged suspension response despite soft driving on a straight road. The principle of operation is the same as with air brakes. They work late and poorly!
I can't find another explanation because I tried all the advice I got and the air is still in front of the LHM pump.