C5 X7 rear suspension fun.

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Re: C5 X7 rear suspension fun.

Post by GiveMeABreak »

What the strut itself Alan?
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Re: C5 X7 rear suspension fun.

Post by ActivaV6uk »

Managed to get a pic part 11.
IMG-20190712-WA0011.jpeg
Looks like part code 1351kw. I'd be interested is a price or recommendations from anyone who knows where I could get it from at a good price. It looks like it's something that C6 owners have all seen before.
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Re: C5 X7 rear suspension fun.

Post by AJM C5 »

GiveMeABreak wrote: 13 Jul 2019, 16:34 What the strut itself Alan?


Oops, no sorry, I meant the sensor arm itself, not the metal swivel arm that attaches to it and in turn that to a bracket onto the anti roll bar. I'd like to know/see it's proper orientation when suspension is at its lowest.

And would it be on the same fuse and ecu as the front sensor would you know?

Thank you.
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Re: C5 X7 rear suspension fun.

Post by GiveMeABreak »

Andy Cooling.PNG
Radiator Outlet Hose part: 1351KW, priced £343.62 :shock: inc. VAT Time to dig out the duct tape I think.


Chevronics have one for £301 inc. plus delivery (variable):
https://www.chevronics.co.uk/product/ci ... er-hose-2/
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Re: C5 X7 rear suspension fun.

Post by GiveMeABreak »

AJM C5 wrote: 13 Jul 2019, 19:47
GiveMeABreak wrote: 13 Jul 2019, 16:34 What the strut itself Alan?


Oops, no sorry, I meant the sensor arm itself, not the metal swivel arm that attaches to it and in turn that to a bracket onto the anti roll bar. I'd like to know/see it's proper orientation when suspension is at its lowest.

And would it be on the same fuse and ecu as the front sensor would you know?

Thank you.

Sorry I'm not with you Alan. There are no sensors on any of the suspension parts apart from the hydraulic regulators front and rear and the body height sensors (1 on each axle on the 4 cylinder engines, with one on each wheel for V6 engines). All the other electronics are contained in the BHI (Electronic Hydraulic Interface at the front, with the suspension ECU).
X7 Rear Suspension.PNG
(33) RH rear suspension cylinder.
(34) Rear suspension accumulator (right).
(35) Rear stiffener regulator accumulator.
(36) Rear firmness regulator.
(37) Rear stiffener regulator accumulator.
(38) Rear suspension accumulator (L.H. side).
(39) LH rear suspension cylinder.

Or did you mean the suspension multilink setup?
X7 Rear Suspension Pivots.PNG
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Re: C5 X7 rear suspension fun.

Post by AJM C5 »

The body height sensor; a single sensor on top of a plastic protective tray in the middle of the undercarriage right in front of the spheres, which a swivel linkage arm to the anti roll bar is connected to. None of the above pictorials. 🤔
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Re: C5 X7 rear suspension fun.

Post by GiveMeABreak »

Ok, they're the Height Correctors.

Front:
X7 Front Height Snesor.PNG
Rear:
X7 Rear Height Sensor.PNG
Be very careful about adjusting anything here Alan and don't get underneath it unless unsupported independently - if the sensor is faulty it can cause the suspension to drop immediately (crush risk).
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Re: C5 X7 rear suspension fun.

Post by AJM C5 »

Thanks, yes those ones. Is that rear pic with the sensor arm pointing 5.30pm indicative of the lowest body height setting would you know, or does it depend how it is programmed on installation... The latter I bet?

Yes, am very careful on getting underneath this vehicle, not that it's possible most of the time anyway, the rear is right on its haunches and doesn't want to move, apart from sinking another inch this afternoon when reaching underneath to that sensor?! Don't worry, the car was chocked and I have extremely long arms 🙄

Cheers Marc
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Re: C5 X7 rear suspension fun.

Post by GiveMeABreak »

In a nutshell, the suspension reference heights are pre-programmed at the factory into the suspension ECU. The height settings are calculated using a complex measuring procedure, some calculations and then the results are compared to the reference heights. If they are within a set variance no action is needed, but only a relatively small adjustment can be made using the diagnostic tool.

If they are out of allowed tolerances, the the clamps need to be adjusted on relevant anti roll bar to allow a bigger adjustment.

If there is an issue, you should be getting a suspension fault code in Diagbox. The height corrector (s) are simple analogue devices that use a potentiometer track to send a signal to the suspension ECU so the height can be determined. These can sometimes get corroded with water ingress and may need to be replaced.

What led to the issue? Was the suspension not maintaining height? Was it suddenly dropping? The rear hydraulic block can also be responsible by not closing off the electrovalve allowing fluid to return to the LDS tank.

Maybe we’ll have a better idea if you can explain what happened and what fault codes you are getting from the suspension ECU?
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Re: C5 X7 rear suspension fun.

Post by AJM C5 »

All understood.

Story is bought car 10 weeks ago knowing about two issues - needed cambelt etc changing, and that the rear suspension usually took a minute after the front to raise itself and usually did so with a slight bump when on the move or stationary.

Three weeks ago the rear was just dropping when driving and then not raising itself when starting at all. Front was on mid to high setting and still works now. I looked at the rear height potentiometer and could see that the bracket it was attached to on the ARB seemed to be catching on the underside of the fuel tank... Bad install I thought. So eased the bracket bolt and moved it 0.5 cm so it didn't catch, without changing its pitch. The arm linkage had also got itself into a a contorted position, but the 0.5cm shift alleviated that too.

Then I looked into the LDS tank, oil seeped out from filler (front up, rear suspension down). Thought it might have been overfilled. Two days ago I syphoned out 2.5 litres of old dirty oil direct from the tank, and another litre yesterday and filled it to the correct level between the basket markings with front and rear on the lowest setting. Started engine and watched for bubbles in the filler, few came along with some dirty oil which I skimmed off with syphon after raising suspension one notch, only the front responded. Lowered suspension again, let it run for five minutes, put cap on, ran Diagbox which couldn't return data on the suspension like it did before?! Switched off engine, then after 10 minutes disconnected battery after car went to sleep.

This morning I connected the battery, ran Diagbox and there are now data and faults reported on the suspension. And one on the BSI which might be to do with disconnecting the battery and reconnecting..

I have not started engine so far today or anything else. I notice that locking and unlocking / opening doors now doesn't set off the suspension/ps motor like it used to, but raising front obviously does even if its noticeably quieter.

I attach a couple of fault pictures:
Attachments
IMG_20190714_104801.jpg
IMG_20190714_104723.jpg
IMG_20190714_104656.jpg
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Re: C5 X7 rear suspension fun.

Post by GiveMeABreak »

So if I understand it the following applies:

The car when driving randomly rises / lowers at the rear
When stationary, the rear can fail to maintain height and has on occasion dropped?

If this is the case, then the likelihood is that the rear stiffness regulator has failed. Basically, this is allowing fluid to return back to the Integrated Hydraulic Block (BHI) that sits under the LDS tank.

There is a test that can be done to determine if it is faulty - but again I stress you need to have the vehicle independently supported before getting under :wink:

Using the following guide to test the rear block:
  • You will need a method of plugging a pipe before you start.
  • You will need a receptacle for catching some LDS
Rear Regulator Check.PNG
  1. You need to uncouple the the Leak Return Pipe shown at (2) from the Stiffness Regulator (arrowed in red).
  2. To do this, unclamp and remove the flexible pipe (starred in red), then plug the fixed pipe to prevent fluid returning (yellow circle).
  3. With the engine running, check the flow of suspension fluid coming from the stiffness regulator, via the flexible pipe you removed, using a receptacle:
    • If the flow is permanent:- there is an internal leak -replace the stiffness regulator
    • If drop by drop:- the stiffness regulator is working correctly
  4. Remove the plug you inserted from the pipe that leads back to the integrated hydroelectric block (BHI).
  5. Reattach the leak return tube (2)
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Re: C5 X7 rear suspension fun.

Post by AJM C5 »

Okay, got that Marc, thank you. Before doing this there is an update.

"The car when driving randomly rises / lowers at the rear
When stationary, the rear can fail to maintain height and has on occasion dropped?"

Sorry, didn't make myself clear.

It used to but not now. Just tested on mini drive around our village green a few times. The rear is permanently on its haunches regardless of the suspension setting including sport mode. Front works in all settings. Back in the garage I loosened the rear bracket connected to the height sensor potentiometer and with engine running I varied the pitch of the potentiometer, and there was no response from the LDS pump. I tried it several times including with a body height adjustment switch in the cabin, which only the front responded to, the rear never did. On videos I watched overnight, the setting of that potentiometer as well as the pictorial you provided above shows settings of between 3.30pm and 6pm, AND when turning it clockwise the pump kicks in and the rear rises. But there was no response from my pump which suggests to me it is not getting the signal. To me that is the primary suspect, what do you think?

Rgds
Alan
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Re: C5 X7 rear suspension fun.

Post by GiveMeABreak »

Unlike the old Hydroneumatic Citroen's (DS, SM, GSA, CX, XM. Xantia) the Hydractive 3 / 3+ systems found on the C5 and C6 systems are entirely different.

Because the system is electronically controlled using electrovalves, the pump does not operate constantly - it only operates when required to maintain the correct pressure. The pump will not engage either when lowering the height.

If the car is now permanently set too high at the rear, then this will be the rear height corrector incorrectly set or faulty. You cannot go visually by the angle of the clamp or height corrector or from any diagrams. The clamp positions should always be marked with some white tippex or paint so they can be realigned on refitting if they ever need to be removed. I suspect now that these are out of kilter and that is why the rear is riding high.

Ignore the Sport setting, as that has nothing to do with height correction - that only cuts in and out the front and rear centre spheres to allow the car to ride on all 7 spheres (normal comfort mode) or on 4 corner spheres (Sport mode- whether manual or automatic). Also do not switch sport mode on as no height correction adjustments can take place when it is in this mode.

Diagbox can give you live data - if you go into the suspension ECU after running a Global test, you should be able to select parameters from the suspension ECU to see what is happening when you command the car to raise and lower.

You need to start adjusting the rear height corrector clamp in very small amounts a bit at a time, until you get it looking almost level. A pit of course is ideal as the car needs to be level on the ground with all 4 wheels on the ground, so you can see what is happening - but you can't really do this on a road as you will be having the vehicle supported in case it drops suddenly. So you may need to adjust a few mm at a time, get out, remove supports, and let her level, then raise, support, lower to normal height and adjust - then repeat until you get it right.
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Re: C5 X7 rear suspension fun.

Post by AJM C5 »

Tested the height corrector after disconnecting, cleaning then plugging it back in, manually adjusted by the millimetre and it does appear to trigger the system and the rear tries to rise, but it won't complete the action.

Converting old coal chute in courtyard into a pit area which I can then roll the C5 back over... Trolley jack and stands are okay for the front, but no way for the rear, too dangerous even if it were possible to raise the car there which it isn't.

So I can't test the stiffness regulator, but I think you're right, so want to order the part but where, no search engine returns anything on 'C5 stiffness regulator' ?! Avoiding CMDealers, would you be able to get me a part number and supplier please? UK, France or... Anywhere..

Thanks
Last edited by AJM C5 on 09 Aug 2019, 09:05, edited 1 time in total.
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Re: C5 X7 rear suspension fun.

Post by GiveMeABreak »

Hi Alan

I'm out and about dealing with triffids in the garden and wood staining today, so will be offline for a bit. I strongly suggest you perform the test in my other post - as the rear stiffness regulator is not cheap and a Citroen-only part. Look at the actuator tests in parameters in Diagbox and check if there are any other anomalies. That test is the official procedure and will rule in or out the regulator. If the oils is flowing significantly back in the direction of the green arrows - any more than drops, then the electrovalve is not working properly and is not closing off, allowing the fluid to return straight back to the tank. That will obviously cause sinking issues at the rear - and where the vavle is intermittently working, the sudden drop in pressure.

The rear stiffness regulator is part 5277N7. It costs £594.16 from Citroen.

I've seen a slightly cheaper one here for plus shipping, for £540.96 plus UK shipping, but have never used them.

https://peugeotcitroendsparts.com/produ ... 277n7.html
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