C5 X7 LDS reservoir cap

[faddy]

The reservoir cap in my 2008 C5 X7 has a pinhole in the top. Does this mean it's the modified cap that doesn't need to be removed when car is lifted?

[GiveMeABreak]

No!
That is just to allow SOME of the pressure build up out of the system - the official technical advice is to remove the cap before the vehicle is raised up when it will be lifted off the ground with wheels unsupported. Failure to do so can weaken the tank which is pressurised when the car is raised down and the fluid is returned back under the weight of the car being lowered to the ground quickly. That pin hole cannot evacuate the additional pressure that can be caused as a result.
Quote from technical documentation:

ESSENTIAL: If raising the vehicle on a lift, wheels hanging, remove the cap of the LDS fluid reservoir. Refit the cap of the LDS fluid reservoir, once you have lowered the vehicle (according to equipment).

[faddy]

No!
That is just to allow SOME of the pressure build up out of the system - the official technical advice is to remove the cap before the vehicle is raised up when it will be lifted off the ground with wheels unsupported. Failure to do so can weaken the tank which is pressurised when the car is raised down and the fluid is returned back under the weight of the car being lowered to the ground quickly. That pin hole cannot evacuate the additional pressure that can be caused as a result.
Quote from technical documentation:

ESSENTIAL: If raising the vehicle on a lift, wheels hanging, remove the cap of the LDS fluid reservoir. Refit the cap of the LDS fluid reservoir, once you have lowered the vehicle (according to equipment).

Touch wood I got away with it today when I had the tracking done. Cap stayed on, not because I assumed that I had the modified cap, but because I dozily didn't think about it till the car was in the air.

Is it only an issue when whole car is raised? What if e.g one side is raised to swap front and rear wheels?

[GiveMeABreak]

Generally if more than one wheel will be raised off hanging freely.

Best practise for changing wheels is to raise the car up to highest setting first, then remove the cap. Raise the car and do the necessaries, then lower the car to the ground and lower suspension then replace cap. Note: I would suggest putting the cap on the driver's seat to remind you to replace it!

Raising the suspension first, ensures that the fluid is locked into the system and the electrovalves won't allow it to flood back into the system, but will allow a controlled flow back when the suspension is lowered, after the car is returned to the ground.

[Paul-R]

Surely if the suspension is raised to its maximum then there will be no further movement of fluid and no need to loosen the cap?

Following this logically, if this is not the case then you should loosen the cap every time you raise and lower the suspension to its maximum - i.e. citraerobics.

[Hell Razor5543]

When the suspension is on high there SHOULD be no fluid movement, but this does assume the valves are in good order. Over time they could leak a little. Loosening the cap allows for wear and tear over time allowing fluid flow.

[Paul-R]

If they leak a little then surely that won't create the rush of fluid that seems to be the problem?

[Hell Razor5543]

True, but why take the chance?

When I had the front tyres changed on my C5 I did loosen the LDS cap, much to the amusement of the mechanics. However, when they lowered her back down she did not (as they expected) bottom out, but remained high. Their response? "We will try and remember that for future work on hydro-pneumatic Citroens. Normally we have to lift them back up to get our jacks back!".

[GiveMeABreak]

There is some movement as even on high when raised off the ground the wheels still extend further. I always do this where I can - but some operations require the car to be depressurised making the high setting impossible - so for wheel changes - I would still use the high setting and loosen the cap myself.

[Paul-R]

Not saying I wouldn't. I was just performing a thought experiment and following a chain of logic.

[Stickyfinger]

MoT intro page HAS this procedure for any C5 being tested.
Thanks to me so has QuickFit (the manager added it)