I have a 1992 2.0 XM which has developed an alarming fault, without warning the back drops for the floor and then returns to it's normal ride height in a split second. It's scary enough when it does this when you are stopped at a junction, but when you are driving along and it does it, it's no joke. The only other thing I have noticed is that when parked the back of the car settles much quicker than the front.
My local Citroen man says the best thing is to scrap it and buy another car from him, I don't want to do this if I can help it, I've had the car for a long time and would like to keep it a little longer.
Does anyone have any ideas?
XM Suspension Problem
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Gary,
Welcome to the forum! A little bit more info about the car - is it hydractive, or just 'ordinary'? When it 'collapses' does it do it at particular times (eg when braking)? How is its service history - LHM been changed recently? When were the rear spheres last changed?
There are lots of things it could be, but best to start simple! Get it on ramps / blocks / stands MAKE SURE IT IS PROPERLY SUPPORTED SO IT CANNOT SQUASH YOU if you disturb something or it decides to have a 'funny'. Find the rear height corrector - not sure exactly where on an XM, but probably in front of the spare wheel and close to the rear anti roll bar (it looks about the size of a tuna tin with lots of pipes coming out of it!). Give the mechanism between the corrector and roll bar a VERY liberal spraying with WD-40. Now run the car from min - max height and back again about 10 times to give it a good work out. Drive it for a few miles and see if it is any better.
If this doesn't work, then you are into replacing some stuff, but that might just do it.
Welcome to the forum! A little bit more info about the car - is it hydractive, or just 'ordinary'? When it 'collapses' does it do it at particular times (eg when braking)? How is its service history - LHM been changed recently? When were the rear spheres last changed?
There are lots of things it could be, but best to start simple! Get it on ramps / blocks / stands MAKE SURE IT IS PROPERLY SUPPORTED SO IT CANNOT SQUASH YOU if you disturb something or it decides to have a 'funny'. Find the rear height corrector - not sure exactly where on an XM, but probably in front of the spare wheel and close to the rear anti roll bar (it looks about the size of a tuna tin with lots of pipes coming out of it!). Give the mechanism between the corrector and roll bar a VERY liberal spraying with WD-40. Now run the car from min - max height and back again about 10 times to give it a good work out. Drive it for a few miles and see if it is any better.
If this doesn't work, then you are into replacing some stuff, but that might just do it.
Hi Gary -
I second Richard's suggestion's on the service history details we need from you - to rule out too much guesswork.
Besides that - I want you to report results from these simple manual tests :
Have the suspension in normal height, engine idle, hand (parking) brakes on.
1) jerk down each corner of the car. It should feel soft and easily press down some 3-5 inches.
2) Alexx - one the best "LHM heads" we have here on board - suggests a further suspension test - namely timing the bouncing frequency of the suspension - i.e. the time for each bounce period when you jerk the suspension down/up and let go. Should be rather close to 1.2sec's.
Faster bouncing means lesser pressure left in the spheres.
3) Open the hatch and sit on the edge your full weight. The rear should gently sink - then slowly re-gain height after some delay.
Your '92 XM is fitted with the Hydractive I system. Hydractive II systems appeared '93 models on. The Anti-sink system appeared together with the introduction of the 2section hydraulic pump '95 models on.
If not allready done - then I suggest you read the following document :
http://www.tramontana.co.hu/citroen/guide.html
- this will at least ensure we use the same "language" [:)]
There is only one thing that's definate to your XM :
You'll get a darned shamefull bad trade-in [:(]
On top of that - it's wellknown that Citroen UK has given up on XM's - as they are very slow (in fact non-) sellers.
I second Richard's suggestion's on the service history details we need from you - to rule out too much guesswork.
Besides that - I want you to report results from these simple manual tests :
Have the suspension in normal height, engine idle, hand (parking) brakes on.
1) jerk down each corner of the car. It should feel soft and easily press down some 3-5 inches.
2) Alexx - one the best "LHM heads" we have here on board - suggests a further suspension test - namely timing the bouncing frequency of the suspension - i.e. the time for each bounce period when you jerk the suspension down/up and let go. Should be rather close to 1.2sec's.
Faster bouncing means lesser pressure left in the spheres.
3) Open the hatch and sit on the edge your full weight. The rear should gently sink - then slowly re-gain height after some delay.
Your '92 XM is fitted with the Hydractive I system. Hydractive II systems appeared '93 models on. The Anti-sink system appeared together with the introduction of the 2section hydraulic pump '95 models on.
If not allready done - then I suggest you read the following document :
http://www.tramontana.co.hu/citroen/guide.html
- this will at least ensure we use the same "language" [:)]
There is only one thing that's definate to your XM :
You'll get a darned shamefull bad trade-in [:(]
On top of that - it's wellknown that Citroen UK has given up on XM's - as they are very slow (in fact non-) sellers.
Measuring the bouncing frequency of the car can be used to determine the condition of spheres, as I described a month or two ago in another post. Frequency should be 0.8-0.9 Hz for new spheres (depending of the car) and up to about 1.1 Hz is acceptable. This should be done with small amplitude (about +/- 1 cm), to minimise influence of the dampers. On hydractive suspension, this test, when done in soft mode, will tell about condition of middle spheres. Corner hydractive spheres can't be tested this way, because of very restrictive damper valves.
Anyway, I'm quite sure that flat corner spheres (whether hydractive or non-hydractive suspension) can't be the reason for sudden dropping. Not so sure about hydractive middle spheres.
Gary, is your XM hydractive (there are also non-hydractive XM-s with 2.0 engine). In case it's hydractive, is this dropping connected with some other event, like turning the wheel or pressing the accelerator or brake pedal. Maybe it occurs in some regular intervals, like 2 minutes?
Anyway, I'm quite sure that flat corner spheres (whether hydractive or non-hydractive suspension) can't be the reason for sudden dropping. Not so sure about hydractive middle spheres.
Gary, is your XM hydractive (there are also non-hydractive XM-s with 2.0 engine). In case it's hydractive, is this dropping connected with some other event, like turning the wheel or pressing the accelerator or brake pedal. Maybe it occurs in some regular intervals, like 2 minutes?
Thanks for your input. The car in in fact a '91 car, not '92 as I said originally, I don't know when the spheres were last changed, I've had it for four years and have done about 20,000 miles in it. The LHM hasn't been changed it that time.
I can't say specifically what causes the car to drop, although it did happen once when I drove over a large pothole in the road, other times it has happened on a smooth road.
I have noticed that the back seems to "bunny hop" over hump back bridges (if I put it in sports mode this doesn't happen).
I have tried the tests above, the front suspension seems fine but the rear suspension seems soft, if I sit on the boot edge the car sinks and then recovers after twenty seconds or so.
I'd be happy for any advice.
I can't say specifically what causes the car to drop, although it did happen once when I drove over a large pothole in the road, other times it has happened on a smooth road.
I have noticed that the back seems to "bunny hop" over hump back bridges (if I put it in sports mode this doesn't happen).
I have tried the tests above, the front suspension seems fine but the rear suspension seems soft, if I sit on the boot edge the car sinks and then recovers after twenty seconds or so.
I'd be happy for any advice.
Ok Gary -
It's clear then that your XM has the Hydractive I type suspension.
Also it seems that basically the suspension is working as it should - the rear should indeed feels soft - as it's much lighter than the front.
But the auto regulation of the Citroen hydraulic suspension - either the system type - will make the rear suspension harder exactly according to the boot load.
What we are looking for are causes for a sudden drop of suspension height on the rear - which can happen at random.
During drive this can ONLY be caused by either of 2 :
1) an unwanted rear brakes activation.
2) a sudden pressure drop (dump) in rear suspension.
Do you by any chance have a habit of resting one of your feets near the brake pedal during drive ? Or are you simply a large shoe size [:I]
What I'm looking for is any small unwanted brake pedal activation - could even be carpetting do this.
The Citroen hydraulic brake compensator (master or pedal) valve is hyper sensitive in it's rear brakes circuit - for technical reasons - to make the rear dive on braking - ensuring the brake load is equalised over the car body.
But this is ONLY at the onset of braking - i.e. first split second on initial braking - or pedal activation.
Any possibility that either the brake pedal itself is touched - or the pedal to valve clearance is too tight - should therefore be investigated.
Even the Brake Compensator valve itself may be at fault - causing the problem. It MAY be possible to trace a faulty brake compensator valve - by judging the leak off flow from the valve's leak off rubber hose.
This is done with engine idle, normal height, parking brake on.
If flow is evident - with correct pedal to valve clearance - pedal not activated - then obviously it's at fault. Some drops now & then - even some rapid dripping may be considered functional acceptable - but not flow or pressure.
Any rapid rear suspension pressure dump I can imagine - would be one or both of the rear wheel spheres being flat.
Remember when you tested the rear suspension for softness ? This is automatically done in soft mode with car at standstill - with the center sphere connected providing the slow movement softness.
When the car is at speed beyond some 19Mph (30km/h) the suspension in many instances will be switched to hard mode - depending on various conditions from sensors - then the center sphere is disconnected.
However the suspension will shortly be force-switched to soft mode every 1 minute by the computer activating the electrovalve - to equalise any pressure difference between rear suspension and the dis-connected rear center sphere.
If a wheel sphere is flat - any small suspension movement will cause rather high shift in volume (flow rate) out the pipe from the suspension cylinder to the hydractive control block - as the wheel sphere has no "soft" gas volume to compress and place the volume shift into.
If this larger shift in volume then coincides with the computer's equalisation of the center sphere pressure - then you get a sudden pressure drop - and the rear dips. Due to the nature of this - it will happen totally at random.
To test this :
Start engine let car come in normal height - then stop engine - turn ignition off - remove key. Now wait at least 30sec's and don't open any doors (important !). Then have 2 assistants open the boot and sit there with full weight
What happens ? does the rear softly sink a little - or any at all ?
Don't start engine - simply insert key and turn ignition on - what happens ? Sudden rear drop by the weight of your assistants ?
My cards are on the rear suspension spheres - and maybe an ace up the shirt on the Brake compensator valve.
It's clear then that your XM has the Hydractive I type suspension.
Also it seems that basically the suspension is working as it should - the rear should indeed feels soft - as it's much lighter than the front.
But the auto regulation of the Citroen hydraulic suspension - either the system type - will make the rear suspension harder exactly according to the boot load.
What we are looking for are causes for a sudden drop of suspension height on the rear - which can happen at random.
During drive this can ONLY be caused by either of 2 :
1) an unwanted rear brakes activation.
2) a sudden pressure drop (dump) in rear suspension.
Do you by any chance have a habit of resting one of your feets near the brake pedal during drive ? Or are you simply a large shoe size [:I]
What I'm looking for is any small unwanted brake pedal activation - could even be carpetting do this.
The Citroen hydraulic brake compensator (master or pedal) valve is hyper sensitive in it's rear brakes circuit - for technical reasons - to make the rear dive on braking - ensuring the brake load is equalised over the car body.
But this is ONLY at the onset of braking - i.e. first split second on initial braking - or pedal activation.
Any possibility that either the brake pedal itself is touched - or the pedal to valve clearance is too tight - should therefore be investigated.
Even the Brake Compensator valve itself may be at fault - causing the problem. It MAY be possible to trace a faulty brake compensator valve - by judging the leak off flow from the valve's leak off rubber hose.
This is done with engine idle, normal height, parking brake on.
If flow is evident - with correct pedal to valve clearance - pedal not activated - then obviously it's at fault. Some drops now & then - even some rapid dripping may be considered functional acceptable - but not flow or pressure.
Any rapid rear suspension pressure dump I can imagine - would be one or both of the rear wheel spheres being flat.
Remember when you tested the rear suspension for softness ? This is automatically done in soft mode with car at standstill - with the center sphere connected providing the slow movement softness.
When the car is at speed beyond some 19Mph (30km/h) the suspension in many instances will be switched to hard mode - depending on various conditions from sensors - then the center sphere is disconnected.
However the suspension will shortly be force-switched to soft mode every 1 minute by the computer activating the electrovalve - to equalise any pressure difference between rear suspension and the dis-connected rear center sphere.
If a wheel sphere is flat - any small suspension movement will cause rather high shift in volume (flow rate) out the pipe from the suspension cylinder to the hydractive control block - as the wheel sphere has no "soft" gas volume to compress and place the volume shift into.
If this larger shift in volume then coincides with the computer's equalisation of the center sphere pressure - then you get a sudden pressure drop - and the rear dips. Due to the nature of this - it will happen totally at random.
To test this :
Start engine let car come in normal height - then stop engine - turn ignition off - remove key. Now wait at least 30sec's and don't open any doors (important !). Then have 2 assistants open the boot and sit there with full weight
What happens ? does the rear softly sink a little - or any at all ?
Don't start engine - simply insert key and turn ignition on - what happens ? Sudden rear drop by the weight of your assistants ?
My cards are on the rear suspension spheres - and maybe an ace up the shirt on the Brake compensator valve.
Exactly the same on my 96 2.1 XM. It seemed to start after both center spheres replaced (LHM replaced at the same time). As far as I can tell the outside spheres are all fine. The car is new to me and I can't be sure of the service history. This is my first XM (after years of CX's).
My obsrvation is that it only happens after the car has been sitting for a long period and then only in the first 50 meters of driving. Otherwise the car seems fine.
regards
sean
hot and sunny Adelaide
My obsrvation is that it only happens after the car has been sitting for a long period and then only in the first 50 meters of driving. Otherwise the car seems fine.
regards
sean
hot and sunny Adelaide