Height Corrector?

deian · Post by **deian** » 21 Apr 2006, 18:52

I've been spraying WD40 around it, and I still get sudden dropping of the suspension when the doors open or i switch the ignition on. Where exactly do I need to spray on height corrector to get it working better?

And when we move the lever inside our cars, is it this that moves the metal rod that goes to the height corrector? Thats what i've gathered so far.

And there is only one height corrector? In the back? Not one in the front is there?

Weird, but clever, simple too.

Thanks

AndersDK · Post by **AndersDK** » 21 Apr 2006, 19:25

Dont think you can spray the sudden drop problem away ...
Yes its the rod you move by the lever inside the car - and it connects to both the rear & front HC's.

The sudden drop could very well be a result of the suspension system "remembering" the height was a bit too high, when all persons LEFT the vehicle. I.e. the load on the suspension was removed then ...

andmcit · Post by **andmcit** » 21 Apr 2006, 21:14

Should be one at each end!!

It's JUST a theory and totally unproven and I no doubt will be corrected here but it sounds like the hydractive middle spheres are being opened up erratically onto the main hydraulic circuit and the differential in the pressure takes some out from the corners!? I've no idea what the reason for this scenario to happen with the central electrovalve mind but it would explain a sudden suspension movement!!

I'm not sure what the suspension spec on your car is, but this would be the case only on the VSX's - I lost thread of the system when Citroen got all fancy with it's Sensations and Expressions etc!

Andrew

deian · Post by **deian** » 21 Apr 2006, 21:41

It's Hydractive 2 (8 spheres)

AndersDK the scenario today was i started engine, did some citrobeotics for some reason (oh yea looking inside the LHM tank to see the physical difference in lhm levels with car high and low). So what I do is, start engine, close door, do citrobeotics, so it was lowered now ok, engine was switched off, and then i open the door, the relays click, and then CLUNK the back end drops even though it was already LOW, it's seems to want to drop even though it physically can't. This clunking doesn't happen so much when it's on normal height. Only once in a while.

Does that provide any clues to you?

Thanks

AndersDK · Post by **AndersDK** » 21 Apr 2006, 22:27

When you remove ignition key, open the door and leave the car, there will be a short delay and then the Hydractive suspension "releases" itself from any activity that would possibly drain the battery.

Its the click from the Hydractive unit's electrovalves setting these units to hard mode - which is the rest (default) mode.
In this mode the extra softness sphere on each axle is isolated from the suspension thereby firming up the suspension.

This should not give any other indications than just the the valves faint clicking. A clunk from the suspension is an indication that something mechanical is at wrong - and that could well be the rear swing arms pivot bearings being dry (rusty) and worn. A very common problem on all hydraulic suspension Citroen models.

To investigate further requires some work ...
The ARB (anti-roll-bar) must be released from at least one swingarm to isolate the arms from each other to move the arm up/dowm for investigation. Usually if one arm's bearings are shot, the other side would not be far behind

Replacing the rear arm bearings is a typical BX/CX/Xantia/XM DIY project. The job has a spanner rating compared to a complete brakes dismantling/overhauling job. Its not too bad really. Repair kits (pr side) vavailable reasonbly priced, containing all bits necessary.

KevMayer · Post by **KevMayer** » 21 Apr 2006, 22:43

My Activa suddenly drops when I drive away from cold.
After say half a mile the rear end suddenly sinks and up to that point the suspension feels very bouncy.
I am convinced that its the hydractive mode staying in hard mode as it is when you first get in the car.
For some reason the 3rd 'comfort' sphere on the rear axle doesn't switch in until the car has been running for a while.
Once the rear end has dropped the suspension feels fine.
I get nothing like this from my turbod Xantia which is just an SX model with the most basic hydraulic suspension.
Could my rear electrovalve for the hydractive system be faulty ?

deian · Post by **deian** » 21 Apr 2006, 22:44

this would also explain why the suspension on the back is not in time with the front when doing citrobeotics wouldn't it

Mandrake · Post by **Mandrake** » 21 Apr 2006, 22:53

Can you describe the conditions that cause your sudden drop a bit more ? In particular what you are doing before it happens, and how easily you can reproduce it.

A sudden drop (or rise) when opening a door is clearly an issue with the Hydractive system, and unrelated to the height correctors.

What happens is that for some reason the Hydractive unit at that end of the car is "stuck" in hard mode when it shouldn't be, when you are changing the height of the car, so the pressure of the centre sphere is not being equalized to the suspension.

When you open the door you trigger the Electrovalves to switch the suspension to soft mode, the valve to the centre sphere opens, and the pressure suddenly equalizes, and if the pressure in the centre sphere was much lower before hand you get a sudden drop, and if it was much higher you get a sudden jump up in the air.

Although you can concoct scenarios where you can make this happen on purpose on an car with no faults, generally it should never happen if you have the engine idling while you are changing heights.

If it does happen with the engine idling, the most likely cause is a faulty Electrovalve. (or two, there is one for front and one for rear)

As it happens I am chasing this problem myself and I have discovered two problems that can cause intermitant sticking in the hard mode and I have experienced both on my car - one is a mechanical problem due to lack of spring tension on one of the internal springs of the Electrovalve, and the other is a faulty (or intermitantly faulty) diode in the electrovalve.

The former problem unfortunately is quite difficult to fix because it involves removing and disassembling the valve which is definately not a "newbie" job, and carries a high risk of damaging the valve. For most people this would require replacing the valve.

The latter problem is easy to work around though - a diode can be connected externally to supplant the internal diode. Any 1 amp (or better) power diode can be used, and it is connected "backwards" with the anode to ground and the cathode to the live wire.

With a faulty diode the symptoms can vary - if it is completely open circuit, that end of the car will switch to soft mode for half a second (enough to cause the jump in height) but will then switch back to hard mode again, until the computer orders the next soft->hard->soft mode change, apon which it will be soft for half a second again.

(Hi Bernie!

)

If the diode is partially faulty, as one of mine is at the moment it can vary at random between functioning ok, sometimes sticking in hard mode, and sometimes the valve will even chatter and click on and off continually.

In another thread you mention harsh ride, I now wonder if you actually have a faulty electrovalve (most likely the diode) and that is the cause of your harsh ride.

If the electrovalve causes the suspension to stay in the hard mode (when it shouldn't) the effect on the ride is EXACTLY the same as a centre sphere being flat, because the centre sphere is isolated.

See if you can reproduce this jumping behaviour at will, and describe in detail the steps you're taking to do so, also perform a bounce test immediately after the jump in height and see if it is stiff or soft.

One piece of good news - if there is a sudden jump in height when opening the door, although that indicates a possible electrovalve fault, it means that the centre sphere at that end of the car must be ok - if the sphere was flat there can be no sudden jump in height!

Regards,
Simon

Mandrake · Post by **Mandrake** » 21 Apr 2006, 22:58

deian wrote:this would also explain why the suspension on the back is not in time with the front when doing citrobeotics wouldn't it

No.

It's normal for the two ends to move at different speeds/times when going from right down to right up.... due to difference in the weight they are lifting and other such details.

Typically it will go up at the back first when lifting because unless the car is heavily loaded at the back it requires much less pressure to lift the back, and only after the back has reached its desired height does it allow the regulator pressure to continue rising to allow the front to then rise.

In the downwards direction either the back or the front can go down first depending on the height correctors, but typically the front would go down first because it is heavier.

Nothing at all to worry about.

Regards,
Simon

Mandrake · Post by **Mandrake** » 21 Apr 2006, 23:04

KevMayer wrote:My Activa suddenly drops when I drive away from cold.
After say half a mile the rear end suddenly sinks and up to that point the suspension feels very bouncy.
I am convinced that its the hydractive mode staying in hard mode as it is when you first get in the car.
For some reason the 3rd 'comfort' sphere on the rear axle doesn't switch in until the car has been running for a while.
Once the rear end has dropped the suspension feels fine.
I get nothing like this from my turbod Xantia which is just an SX model with the most basic hydraulic suspension.
Could my rear electrovalve for the hydractive system be faulty ?

Hi Kev,

I had exactly this problem too and I finally managed to fix it and confirm the cause

It is in fact a lack of tension on the smaller of the two springs inside the electrovalve - the one that pushes the needle valve in the direction of the soft mode.

Unfortunately getting the valve apart is very difficult and risky, I only did it because I had a spare one on hand in case of disaster.

See: http://homepages.igrin.co.nz/simon/imag ... valve2.jpg

The spring is the one on the right hand side of the pin.

Further disassembled: http://homepages.igrin.co.nz/simon/imag ... valve3.jpg

Spring stretched: http://homepages.igrin.co.nz/simon/imag ... valve4.jpg

It's probably better to just replace the electrovalve rather than trying to repair it, I had a terrible time getting it apart and figuring out its problems, but since Citroen parts are so expensive and hard to get over here I thought it was worth the effort. (Yes that is thread lock on the thread, which is why its so damn hard to get apart)

I mention it mainly to confirm that the problem is indeed the Electrovalve.

Regards,
Simon

deian · Post by **deian** » 21 Apr 2006, 23:08

Good work Mandrake, when you put it all together like that it makes sense, so yes from low it still wants to drop, then from normal height upon opening the door it does sometimes jump up, not sure if it actually jumped down today. And yes they ride does seem rather harsh.

Also I was under the bonnet today and randomly heard 'relays' clicking, no engine running, no doors open, nothing, just 'click click' (remember this was from the front), surely this can't be related to the back end too? I'm scared of the electrovalves! I'll try the suspension bearings too.

Now this is what I love about Citroens in comparison to say a 'toyota'

', they are everchanging in a technical way. Bless them.

Thanks

andmcit · Post by **andmcit** » 21 Apr 2006, 23:14

God, don't mention the "H" word, he'll be back, you're just encouraging him!

Andrew

deian · Post by **deian** » 21 Apr 2006, 23:18

Yes, i was thinking about him when i was writing that word.... let me edit the post to something more suitable. Our secret ok!

andmcit · Post by **andmcit** » 21 Apr 2006, 23:22

Mandrake · Post by **Mandrake** » 21 Apr 2006, 23:24

deian wrote:Good work Mandrake, when you put it all together like that it makes sense, so yes from low it still wants to drop, then from normal height upon opening the door it does sometimes jump up, not sure if it actually jumped down today. And yes they ride does seem rather harsh.

Also I was under the bonnet today and randomly heard 'relays' clicking, no engine running, no doors open, nothing, just 'click click' (remember this was from the front), surely this can't be related to the back end too?

So you heard a clicking noise from down the front of the engine bay at about 1 click per second ? Yep this is exactly what mine was doing yesterday

Try listening close to the radiator or put your hand on the electrovalve and see if you can feel it clicking. Or perhaps unplug it while its happening and see if it stops. (It's the plug with the wire clip attached to the side of the unit, you just squeeze the wire inwards and push the plug down...)

If so, it sounds like you have the same faulty diode problem I do.

The Hydractive system stays active for 10 minutes after you turn off the ignition if the doors are left open, or 30 seconds afterwards if the doors are closed. If you open a door it comes back on, and stays on for another 30 seconds after the doors are closed.

This is called the "anti-jolt" system and the theory is that if there is going to be a weight change due to people getting in or out that a door will be opened, so it activates to allow the pressure to equalize to prevent exactly the jolts you're seeing.

The clicking happens because when the diode is faulty the computer detects a fault condition and cycles the valve off and on again in an attempt to rectify the problem. It actually cycles both front and back valves in unison so a faulty front valve that is causing the fault condition will cause the rear one to get cycled on and off as well. (Or vica versa)

Regards,
Simon