citroen c5 x7 air bubbles in hydraulic system

[verdi]

Hi All
After a firm ride I checked that there are bubbles air in the LDS reservior. I bleeded the system till the LDS became clear. (Bleeding as per Marc procces)

1. LDS cap off.
2. Start the engine.
3. Setting suspension in high position.
4. Setting suspension in low position.
5. Turn the steering wheel slowly lock to lock (do not hold the steering wheel at the lock limit!).
6. Return steering wheel to centre position.
7. Engine off.
8. Wait for all the bubbles to disappear.
9. Check fluid is between the marks in the procedure.
10 Repeat as necessary.
11. Raise vehicle to normal height.
12. LDS cap back on.

The ride was improved but after a day I got the same issue. bleeding again and so on...
No visible leak.
No loose of LDS.
I've checked the Steering as it appear in another thread and found it dry.
A few questions
The meaning of air in the system should be a leak from some where?
At past the car was hang without pick her to max. highest and opening LDS cup - could it made the air go to the system?
should I do a bleeding with 0.5 bar pressure?
No wet areas, but apart of the boot on the front right strut has different dark color - May be any connection? - again it doesnt wet.
Any advises Please.
Many Thanks.

[GiveMeABreak]

When fluid dries or becomes congealed it will turn a darker colour, so you may have a fine strut leak. Best thing is to gently clean the area up and then check to see if you get any fresh oil there over the next few days / weeks.

[verdi]

Thanks Marc
I will look again on it.
Is there any hose on the strut which cause any leak?

[GiveMeABreak]

Unlike earlier C5s there are no fluid 'leak back' return pipes, so any weeping or fluid there not from a spill is likely to be a leaking strut. These are made of bonded plastic to metal, so can't be repaired, requiring a complete strut replacement.

[Milpav]

Hid, did you find out what was the problem? I have similar problem with requiring air in the system every few weeks, no leaks found but somehow air keeps requiring

[Kees]

I wonder how you know that there's air in the system, because in the LDS fluid are component to prevent it from foaming.
If you think it's when you release the cap of the LDS tank and notice that there is some pressure inside, we'll this is normal.

[Stickyfinger]

The LDS cap SHOULD have a tiny vent hole in it....this prevents (helps against) the tank bursting...it should not be pressurized.

[Kees]

@Stickyfinger:
No, you're not right, this tiny hole is a kind of one way valves, to let pressure in, inside the cap is a rubber ring this shuts off the hole with pressure inside the tank.

[Stickyfinger]

Errr OK....my 2009 C5 was a "normal" cap, just a hole.

Why would the tank need to be pressurised ?

[Kees]

My car is from 2008 and have this cap, the hole systeem keeps under pressure, there is a tiny sphere also at the back of the pomp, this is the reason, that the car stays at a certain level and you need the diagbox to depressed the system.

[Estately]

LDS in the reservoir on the low suspension setting with air dissolved looks like tea with milk and when air has gone, looks like tea without milk. Air in LHM made it appear light in colour, possibly like lime aid.

Like you I am surprised that air gets into the LDS since it is always going to be under pressure, however if work has been done on the suspension system it is possible that air has got in.

There is a push on braided rubber pipe on the rear suspension which can split at the point where it is fitted. You can cut back to non split pipe and refit.

Our C5 showed signs of air in the LDS for some weeks even after repeated citrobics operations, with the reservoir cap off it was cleared by setting the system to high and jacking the front off the ground. Then the suspension was lowered to the lowest position and air bubbles came out of the reservoir as the rear settled. Be prepared for excess fluid overflowing, ask me how I know.

There has been no air detected since.

Hope that helps.
Andy