XANTIA STRANGE GROANING NOISE FROM FRONT SUSPENSION

moggy74 · Unread post by **moggy74** » 30 Sep 2009, 13:03

This has been happening for some time,what it is...when the cars been standing few hours i notice the rear suspension will sink to its lowest point,even when the car is in normal ride height,then when you start the engine,after a few seconds theres a strange groaning noise and the front of the car drops,then the car levels off and everything seems normal...(well as normal can be with a Xantia !)when you start the car...

ive just fitted a new hp pump,but the problem still there..(HP pump fitted because of leak not to try and cure this small issue)...

any ideas on this please

red_dwarfers · Unread post by **red_dwarfers** » 30 Sep 2009, 14:21

The groaning noise will be due to lack of lubrication on the front struts, AKAIK this is the only moving part that doesn't have deliberate leakage. Best thing to do is to stick some grease on there, though im not sure which type of grease is recommended im sure someone will be along soon to point it out

The rear sinking, does you're Xant have an Antisink valve?

Im not sure what could be causing the front to sink upon startup...could be a knackered accumulator I suppose?

Unread post by **citroenxm** » 30 Sep 2009, 15:06

Hmmm, not so much the struts, Id be more inclined to say that the ANTI Sink Valve is giving in and letting the car down..

Ive a couple of Xantia 2's here, that do it just after the key is switched off, they give off a good groan and drop a bit..

Personally, I wouldn't worry about it - a citroen SHOULD sink anyway, as long as the car comes up..

The front anti sink valve is under the LHM tank, the rear on the side of the anti sink sphere in the centre...

Paul

moggy74 · Unread post by **moggy74** » 30 Sep 2009, 15:18

Xantia is a year 2000 X reg HDI,so does it have anti sink....?..also i bought a new accumaltor sphere when i got the new pump,the nice helpful chap at Pleides said i best fit one as a knackered sphere could of damaged the pump.what do you think?

Many Thanks

davetherave · Unread post by **davetherave** » 30 Sep 2009, 15:20

Mine gives a groan after switch off sometimes, just another quirky feature!
The back of mine also sinks, thats not a quirky feature that means i need a new sphere!

Unread post by **RichardW** » 30 Sep 2009, 16:52

The groan is well known on anti-sink Xantias - it is caused by fluid escaping past a partially closed front anti sink valve and making a pipe vibrate against the body work. They did it from new apparently, and there were various 'fixes' applied (a bit of foam rubber behind the pipe for instance!). It's more prone if there is a leak somewhere at the rear which causes it to sink, as then there is a pressure imbalance in the system, and fluid is more likely to force its way past the anti sink valve. Rear sinking is perhaps failed antisink valve, or leaking strut. Note that the rear anti-sink sphere has little or no effect on whether it sinks or not - it is in fact a brake accumulator

If it's flat, and the AS valve is working, then the usual symptoms are the rear sinking just after start up as the pressure rises and the AS valve opens.

Unread post by **citroenxm** » 30 Sep 2009, 20:25

Thankyou Richard for confirming, I always knew it was the anti sink valve, but never knew as much infor as yourself..

The Series One, 1993 with anti sink DOES NOT do it, however, the 2000 W reg HDi Does do it....

Strange stuff..

Paul

paulbx · Unread post by **paulbx** » 01 Oct 2009, 14:46

Folks

my x reg hdi 90 xantia estate does exactly this from time to time. I ignore it!

paulb

HDI Dave · Unread post by **HDI Dave** » 07 Nov 2009, 15:37

davetherave wrote:Mine gives a groan after switch off sometimes, just another quirky feature!
The back of mine also sinks, thats not a quirky feature that means i need a new sphere!

Mine's doing exactly the same, glad i found your post Moggy,hope you don't mind me borrowing some info : )

Just out of interest, which sphere am i looking at replacing?
Cheers, Dave.

Unread post by **Old-Guy** » 07 Nov 2009, 18:07

Dave

It's the centre rear anti-sink sphere that needs replacing.

Please support the car properly and securely before venturing underneath - it's too easy to kill yourself when the suspension suddenly sinks!

Rear sinking is perhaps failed antisink valve, or leaking strut. Note that the rear anti-sink sphere has little or no effect on whether it sinks or not - it is in fact a brake accumulator Confused If it's flat, and the AS valve is working, then the usual symptoms are the rear sinking just after start up as the pressure rises and the AS valve opens

Not quite true. The A/S sphere is a pressure reserve. On the move, primarily for the brakes. When the engine is stopped, it ensures that the rear A/S valve closes smartly (and stays firmly shut). It then provides some limited capability for restoring the ride height when the rear is loaded. e.g. If it's in good condition, when you fill up with fuel, after 25-30L the rear suddenly rises all by itself - weird if you're leaning against the car watching the bill mounting!

Željko Nastasic´ and Gábor Deák Jahn's 'The Citroen Technical Guide' provides a comprehensive explanation (with diagrams) to the various hydraulic systems. You'll find it on my web site where there's also a step by step guide to changing the spheres.

I suggest you at least bleed the rear brake line (very long) after changing the A/S sphere to wash any sh1t out of the rear lines. LHM should be clear bright green. The brake lines, being long dead-ends, are often full of dirty, cloudy, yellowish liquid that was once LHM.

Unread post by **RichardW** » 07 Nov 2009, 22:29

I'm pretty sure the correction of the height comes from the accumulator - the anti sink sphere is on the 'corrected' side of the pressure, so can't provide a pressure reserve. I posted a long explanation of the A/S system at the bottom of page 1 of his thread:

http://www.frenchcarforum.co.uk/forum/v ... hp?t=28575

mostly gleaned from Gabor's guide, I have to say....! Plenty of room to debate it ad-nausem though!

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