C5 rear suspension sinking

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RustyUK
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C5 rear suspension sinking

Post by RustyUK »

Hello all,

My C5's been behaving itself quite nicely since my engine rebuild last spring/summer, alas, last week it suffered a ruptured front-to-rear hydraulic pipe so the rear circuit shot all its blood over the driveway. I wasn't aware of this at first, but soon figured it out after driving off (I thought it was a bit lower getting into too!) - horrendous thumping from the rear, and I have to drive over speed bumps to get anywhere. Circled back around the block and had it recovered to an indy pug garage in town.

They replaced the pipe (had simply corroded) and relived me of £320. Lovely.

Except now the rear won't maintain its height. It's constantly pumping-up-then-sinking at normal and intermediate ride height. Doesn't seem to want to rise all the way on maximum. Seems a little hesitant to sink all the way down on minimum. I've hooked the lexia up to it, no errors, de-pressurised via lexia in a bid to bleed any air out of it, done more citrobics, and absolutely no change. The pump motor must be running almost constantly while driving, I can hear it every couple of seconds. Had to set it on low to just prevent it burning out my battery (and motor!) on the driveway. The front meanwhile rises and lowers normally.

Any ideas chaps? Not sure how the hydraulics work exactly, it's the 2001 2.2 six-sphere model with the sport button. Are there any valves at the rear, or is it all contained in the pump assembly at the front? Might it be a failed rear strut leaking fluid back? (remembering it drove a few hundred meters at low speed, over speed bumps, fully de-pressurised at the rear, but I have really no idea who I could take it to round here now to get that seen to). I don't mind saying, I feel a bit sick at the moment.
KP
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Re: C5 rear suspension sinking

Post by KP »

There is the hydractive valve at the rear i believe in those model so its possible its leaking back.

Also could be that one of the struts has really let go and is leaking back all the time, a leak-off test would confirm this from side to side.

When parked up after so many minutes it should go to sleep and then only raise when you go back to the car and unlock it, i have found this with some older more abused C5's i've come across.

I'd be tempted to take it back to the garage and just be honest with them and say look, it never did this before and i've bled the system but something still isn't right.
RustyUK
Posts: 91
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Re: C5 rear suspension sinking

Post by RustyUK »

Humm, it didn't seem as bad this morning on the drive to work, but still had a twitchy arse after I parked up. Are there any sneaky bleed points I could try bleeding air from myself? I got to know the Xantia's hydraulics quite well, but in all the years I've had the C5 I've never really had cause to work on its hydraulics. Is there any dismantling or removal of the pump assembly required to change the front-to-rear pipe? I gather it's an awkward job but not sure what they disturbed in the process.

Not sure if I want to take it back to the same garage. Partly I find it difficult to put my faith in any mechanic, particularly when given a car back that clearly isn't quite right causing questions over their honesty (perhaps they gave up and hoped I wouldn't notice). They may not even have identified this isn't normal behaviour, and probably don't know anything more than I do about it. Two ways of looking at it, they were paid to replace an awkward component and that was done without leaks. Another component may have suffered damage before they got to it. On the other hand, some people would shout and scream about the new fault which may or may not be the garage's cause. I guess I see little point in giving a garage grief who I don't trust to have the skills to rectify a quirky system like this.

There's a Citroen indy in Bradford I trust but it's a hell of a faff bringing it in from Wakefield - like most 9-5 folk I'm time-poor. Argh.
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Hell Razor5543
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Re: C5 rear suspension sinking

Post by Hell Razor5543 »

What you may need to do is to hook up a Lexia, and then fully depressurise the system. if there was air in the system I would imagine this would help clear it. This post might help;

http://www.frenchcarforum.co.uk/forum/v ... ip&start=0" onclick="window.open(this.href);return false;
James
ex BX 1.9
ex Xantia 2.0HDi SX
ex Xantia 2.0HDi LX
Ex C5 2.0HDi VTR
Ex C5 2.0HDi VTR

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RustyUK
Posts: 91
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Re: C5 rear suspension sinking

Post by RustyUK »

Hell Razor5543 wrote:What you may need to do is to hook up a Lexia, and then fully depressurise the system. if there was air in the system I would imagine this would help clear it.
As said, that was among the first things I did, no change. However I spent some time with it just now and I believe it may only be the height sensor. With engine off I can hear the valves actuate to lower it down, then it pumps up, click and hiss as it lowers down, pump up etc, so the ECU is probably confused about the actual height rather than loosing pressure due to a strut or rear valve leak. Whether the sensor has been disturbed in the process of replacing the pipe, or possibly damaged by driving over bumps with no rear suspension I'm not sure, but going to concentrate my efforts there first. Very easy to access with the rear on wheel ramps.

I'll see if I can read off the height sensor via the lexia too.
I think you pasted the wrong link?
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Hell Razor5543
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Re: C5 rear suspension sinking

Post by Hell Razor5543 »

Oops! I meant this one;

http://www.frenchcarforum.co.uk/forum/v ... 31#p398531" onclick="window.open(this.href);return false;

Last couple of posts.
James
ex BX 1.9
ex Xantia 2.0HDi SX
ex Xantia 2.0HDi LX
Ex C5 2.0HDi VTR
Ex C5 2.0HDi VTR

C5 2.2HDi VTX+
Yes, I am paranoid, but am I paranoid ENOUGH?
Out amongst the stars, looking for a world of my own!
RustyUK
Posts: 91
Joined: 12 Feb 2008, 22:35
Location: Pontefract
My Cars: Citroen C5 X7 2.0 Hdi Saloon
Toyota Aygo (C1/107!)
Dodge Caliber SXT 1.8 (for sale...)
x 2

Re: C5 rear suspension sinking

Post by RustyUK »

Just a quick update for the benefit of anyone else coming across this problem. Thanks to this post: http://www.frenchcarforum.co.uk/forum/v ... =3&t=43459 I've fixed my problem. Turns out the height sensor was refitted incorrectly. They must have dropped the rear subframe to route the new pipe above it, to which the height sensor is attached, joined to the anti roll bar via a link rod.

The end of the 'dog bone' link rod on the sensor can either point upwards or downwards. It's supposed to point down, but seems if it's reassembled pointing up (sensor about 180deg out of position) the suspension ECU obviously gets confused. It won't go all the way up on high and as landyman points out, it'll cycle up and down at normal height as it hunts for the right position. I expect this cause is probably true of other C5's reported seen parked up twerking their rears.

An easy fix! I'll let my local garage know out of courtesy, an easy mistake and easily identified.
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