C5 Suspension issue?

[thundermaster]

Good morning to everyone,

On the occasion of changing the front left suspension bottle with a used one, due to a leak, I discovered something strange.

The car runs normally at normal height, lowers to low, and rises to mid-high too. At the highest setting of 10 km/h the following happens: The car rises, but the suspension pump never stops working, and at some moments a slight hissing sound is heard from the pump. The pump only stops working if I hit the brake, and starts again when I let it. The dashboard never shows the high position indicator. like it never shows that it has completed the lifting process to the last level. Any opinion?

Many thanks!

Nikos

[GiveMeABreak]

Sounds like the height corrector (s) or the suspension heights are out of kilter, so this is causing the BHI (Hydraulic Pump Interface) to constantly operate the pump. It thinks the car is not at the correct height at the highest setting so is constantly operating the pump.

I would not let this continue, or you will blow the fuse when the pump overheats, as it is not intended to run constantly like the old LHM based systems on older Citroens with a mechanical pump. It is only intended to operate occasionally to maintain the height.

You have several choices:

1) Live with it, as for the odd occasion you need to raise the car to maximum that should suffice.
2) Undertake the correct height measuring calculations for the suspension system (a specific procedure see below for link), then enter the resulting figure into the suspension ECU via Diagbox and the system will make minor adjustments. This may correct it.
3) Failing the above, you may a height corrector starting to go, but I would expect a suspension warning if this is the case and is outside the reference values. If the suspension ECU can't understand the data or the data is inconsistent from any of the height correctors it will flag a warning at some point.

Here is my post detailing the complete procedure (with diagrams) for measuring and checking the heights on a C5 MK II:

C5 MK II Suspension Height Checking & Adjustment Guide

[thundermaster]

Many many thanks Marc,

I forgot to change my car in my profile, now I have the X7 2.0i 16v, is it the same process?

Thanks again.

[GiveMeABreak]

Please do change your profile, as no, this is not the same. There are different procedures for the MK I, MK II and X7 MK III. This is the correct procedure for the MK III X7 4 Cylinder engines only.

viewtopic.php?p=559127#p559127

There is yet another one for V6 X7s.

[thundermaster]

Thank you again, I think I better find a garage because the procedure needs special tools and a ramp,, but I am not sure that Greek dealers can undertake this so detailed and precise work...

[aerodynamica]

I have the exact same issue. I connected the diagnostic reader to the car and it shows the live data for the suspension heights. When I set it to maximum height the programmed height setting is 170 steps for the front height sensor so the suspension starting at around 141 at normal height raises and reaches 169 steps where it stays - never reaches 170 and so the pump keeps going. If I could change the target value to 169 it would reach it and the pump would stop. Physically the suspension does pump right up to the highest position but the front sensor only ever reaches 169 steps not the 170 it needs to satisfy the system.

[thundermaster]

When I bought the car two months ago at a ramp check, when they lowered it, the rear wouldn't go up. I finally took it to the Citroen dealer, and they told me that the rear robot (that's what they call the rear height sensor in Greece) was stuck. It was serviced and has been fine since, although I have noticed that the rear of the car, in normal driving position, is now slightly more raised than the front. I don't know if what they did there has anything to do with what I noticed. I asked them three days ago about what I noticed and they said it's ok and to ignore it, I say "how is it ok since it shows this at the highest level?", I should probably find another garage.

[GiveMeABreak]

I think you should, but if it has started sticking due to rust or wear of the internal sensor tracks, then it's probably time to replace it.

Be aware not to get underneath the car at any time unless it is supported with an independent jack or on a ramp as the car can suddenly drop and crash to the lowest level without warning if there are suspension problems and it will crush you.

[thundermaster]

Good morning,

I've never had the confidence to get under a hydropneumatic myself, when it doesn't even have extra support.

Yesterday I found that the pump stops after about 40 seconds at the highest point. But when you turn off the engine and put it back in forward, it starts again. A workshop must be found to undertake the diligence of measuring the heights and perhaps making some adjustments. The height sensor never got stuck again except for that one occasion, or so I think...