Air in suspension system c5 x7

[nomad123]

Hello again!

My car is C5X7 2010 2.0hdi 103kw exclusive.
I have done suspension bleeding procedure 3-4 days in a row but the air keeps reappearing in Lds tank.
My procedure:
1. Start the engine
2. Setting suspension in high position
3. Setting suspension in low position
4. Lds cap off
5. Steering wheel slowly 5-10 times from lock to lock.
6. Engine off, ignition on
7. Depressurise suspenion using lexia
8. Waiting for all the bubbles to disappear
9. Lds cap back on
10. Start the engine and repeat everything 3-4 times until there is barely any air showing in lds tank.

After there is no more air, I drive my car for about one day. After one day I do the same procedure to check for air and its there again. So I do same procedure again but air keeps reappearing.

Reason I do this is because after 1 day of driving car losses its smoothness. I can definitely feel the diffrence when there is no air in the system.

There is no any lds leaking anywhere.
What could cause air in the system to reappear?

Thanks

[myglaren]

My first place to look would be the power steering.

[Sloppysod]

I read somewhere that when Citroën bleed the system they use a slight positive pressure.
So, when I bleed my LDS system I applied about 5psi to the header tank, then carried out the procedure you stated above. Worked a treat.
My set up WAS, a piece of pipe(screen washer) connected to a spare cap from a brake fluid reservoir bleeding kit that screwed onto the LDS tank., then attached a bicycle pump to the other end of the pipe and applied the pressure. My bicycle pump has a tyre pressure gauge.
WARNING - too much pressure could split the LDS tank.

[nomad123]

Thank you for your answers.

Can you please explain a bit more how to check power steering for air leaks?
Should I check the pipe going from LdS tank to power steereing or something else?

[GiveMeABreak]

You don't depressurise the system mid way through the procedure! I already provided a link to the guide: You either depressurise the vehicle using Diagbox at the beginning of the procedure or just put the car into the low position and follow the same.

viewtopic.php?t=72555

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.

[nomad123]

Hi Marc,

If I don't depressurise the system after full steering wheel lock to lock procedure than I can't see lds fluid.
I prefer to set it between A and B marks when system is depressurised as stated by Citroen.

Even if I fill Lds fluid to A and B marks in low position and do the entire procedure with no more visible bubbles once I depressurise the system again the bubbles reappear.

[GiveMeABreak]

No, this makes no sense!

If you are going to depressurise the hydraulic system, it must be done before you start the procedure. Turn the wheel lock to lock a few times, rest and allow the 'fizz' to dissipate. When it has gone, top up top levels and then return the car to normal height.

[nomad123]

If I understood you correctly, I should turn steereing wheel lock to lock while system is depressurised?
I haven't tried this because I thought I can't turn my wheels as they may hit the side of wheel arch because car is so low when system is depressurised.
Did I understood you correctly?

[GiveMeABreak]

Yes, that is the whole point You can't bleed the system when it is pressurised, as air will get in through the LDS tank and you won't be able to return the fluid to the tank that is carrying any potential air bubbles.

Make sure you are on flat ground and away from any obstacles like the kerbside of a road. Turn the wheel slowly and don't hold it at each end when you reach resistance at full lock. Repeat a few times if you like, then return to centre position switch engine off and allow bubbler to disappear and check fluid level.

[nomad123]

Okay, thanks Marc!
I will try this procedure today.
I hope after repeating this procedure air will stop reappearing.
I will let you know when I'm done.
Thanks again!

[GiveMeABreak]

Without doing it this way, you will only be passing any air round the system, so will never get it out otherwise.

[nomad123]

So Marc,
I have done the procedure 4 times in a row. I could definitely see some extra larger bubbles coming up when turning steering wheel lock to lock while system is depressurised.

I will drive the car today and do this procedure tomorrow again in hope no new air bubbles reappear.

One quick question.
Does it matter if I remove lds cap while car is in high setting and then put it in low and depressurise the system or should I depressurise the system first and then remove lds cap? Or it doesn't matter?

Also when I'm done with bleeding I put lds cap back on and then put car to normal setting. Should I remove it once the car is in normal setting again and then put it back on? Or this also doesnt matter?

[GiveMeABreak]

Remove the LDS cap before lowering the vehicle to the lowest position to allow the pressure of the oil to escape when returning into the reservoir - this also allows LDS to evacuate if the tank has been over-filled. Just replace the LDS cap when you have finished all the operations and the vehicle is back to normal height.

You may also find this useful when a garage raises the vehicle with wheels hanging:

viewtopic.php?t=62058

[nomad123]

So it's me again.
After about 3 days of driving I have depressurised suspension and there is plenty of air again.

What should I check first? Someone mentioned power steering? How can I check if power steering is bringing air to the system?

[GiveMeABreak]

The bleeding system covers the power steering - the same LDS fluid from the same reservoir is used for the electric power steering. You will find that 'fizz' will go after a few minutes.

Have you checked your steering rack pinion lately? The X7s suffer greatly from rusting pinions on the rack, leading to destruction of seals and further penetration of rust internally. This is a common fault (I was on rack number 3 before selling mine on). If you have the start of this problem, there may be a small amount of air getting in.