Suspension Conundrum - ** Sorted ** :-))

sandancer · Unread post by **sandancer** » 05 Apr 2004, 12:17

Hi All,
Yes, yet another query on suspension [;)]
I've got a Xantia 1.9TD estate, 98R. Six spheres, non-hydractive. All spheres replaced last year.
Replaced the front pair two weeks ago as one had gone flat. Correct procedure followed with Citrobics etc. Ride back to normal and Stop lamp extinguished after 3 seconds or so.
Now, the ride is choppy, more at the rear and Stop light takes around 10 secs to go out after an overnight rest.
Points to note:
<ul><li> Pressure release valve ticking interval around 1 and a half minutes. </li><li> Corner bounce test ok - rear softer than front. </li><li> Car height corrects ok front and rear when sitting on bumper. </li><li> Manual height adjustment sluggish at rear when raising, but otherwise ok. </li><li> Car height correct and spring mechanism underneath well lubricated and free. </li><li> With engine just turned off, rear does NOT autocorrect when weight is added. </li><li> Rear drops slightly when engine turned off. </li><li> When starting, suspension lifts to normal height after around 20 secs with no dropping. </li></ul>
From what I can understand from previous posts, the accumulator is ok, as are the corner spheres. So may be the anti-sink (as the car doen't sink on startup).
Any ideas???
Mark
LATEST: SORTED - Was the Accumulator Sphere. Replaced and all is good, including better handling and responsive brakes.
Many thanks for all your help.
Mark [:D]

Robin · Unread post by **Robin** » 05 Apr 2004, 16:22

Mark, sounds like the accumulator to me. If you load the back of the estate WITHOUT the engine running and the rear sinks and does not rise again then either the Acc. is flat or the height control is faulty. I would go for the accumulator first though as you say the HC mechanism is free and the car raises afetr loading when the engine is running.
The sinking after starting is not a normal as designed response. The anti sink valve will only open when the pump side pressure exceeds the system pressure. If the sinking feeling remains it could also indicate a flat or tired accumulator. They can break a seal or diaphragm.
The car should raise itself when you fill with fuel too assuming you put in about 45 litres or more.
Robin

sandancer · Unread post by **sandancer** » 05 Apr 2004, 17:04

I filled the tank full from almost empty yesterday and definately did not rise. I was always of the impression that when the accumulator is on its way out the ticking increases in frequency, or does this only happen when the acc. sphere is totally flat?
Mark.

Robin · Unread post by **Robin** » 05 Apr 2004, 20:45

Mark, I have to admit that I do not use the ticking frequency to confirm much. That will argued over in this forum I do not doubt.
I prefer to use an understanding of hydraulics and physics!
The accumulator, if in good condition will give the reserve pressure to correct height until exhausted and it is then recharged next time you start the engine. Flat or full once the system is charged and running at correct pressure the pump regulator will tick just the same.
From personal experience of my 98 Xantia 1.9td Estate the changing of a flat or tired acc sphere makes significant differences to several aspects of the suspension including ride. Robin

AndersDK · Unread post by **AndersDK** » 05 Apr 2004, 22:20

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by sandancer
Pressure release valve ticking interval around 1 and a half minutes.<hr height="1" noshade id="quote"></blockquote id="quote"> -> Indicates a good acc sphere.<blockquote id="quote">quote:<hr height="1" noshade id="quote">Corner bounce test ok - rear softer than front.<hr height="1" noshade id="quote"></blockquote id="quote"> -> rear suspension is allways softer than front.<blockquote id="quote">quote:<hr height="1" noshade id="quote">Car height corrects ok front and rear when sitting on bumper.<hr height="1" noshade id="quote"></blockquote id="quote"> -> indicates the HC's and linkages operating normally.<blockquote id="quote">quote:<hr height="1" noshade id="quote">Manual height adjustment sluggish at rear when raising, but otherwise ok.<hr height="1" noshade id="quote"></blockquote id="quote"> -> you might have a problem on the adjustment of manul height setting on rear.<blockquote id="quote">quote:<hr height="1" noshade id="quote">Car height correct and spring mechanism underneath well lubricated and free.<hr height="1" noshade id="quote"></blockquote id="quote"> -> you have ensured the standard problems are out of the question [:)]<blockquote id="quote">quote:<hr height="1" noshade id="quote">With engine just turned off, rear does NOT autocorrect when weight is added.<hr height="1" noshade id="quote"></blockquote id="quote"> -> Depending on system leakage, you may have from few seconds to several minutes before the antisink valve closes off the HC feed for any height correction.<blockquote id="quote">quote:<hr height="1" noshade id="quote">Rear drops slightly when engine turned off.<hr height="1" noshade id="quote"></blockquote id="quote"> -> I suspect the front would also drop slightly, at least when getting out of car. This is related to above.<blockquote id="quote">quote:<hr height="1" noshade id="quote">When starting, suspension lifts to normal height after around 20 secs with no dropping.<hr height="1" noshade id="quote"></blockquote id="quote"> -> I think this is pretty much the average, when car has been left parked over night.<blockquote id="quote">quote:<hr height="1" noshade id="quote">
From what I can understand from previous posts, the accumulator is ok, as are the corner spheres.<hr height="1" noshade id="quote"></blockquote id="quote"> -> YES [:p]<blockquote id="quote">quote:<hr height="1" noshade id="quote">So may be the anti-sink (as the car doen't sink on startup).<hr height="1" noshade id="quote"></blockquote id="quote"> -> I doubt it. If all spheres are only approx 1 y old, it's unlikely the anti-sink sphere is flat, as it's only charged to the rear suspension pressure, much less than the main accumulator. But sh!t happens, especially if the spheres were recon units.<blockquote id="quote">quote:<hr height="1" noshade id="quote">Any ideas???
Mark.<hr height="1" noshade id="quote"></blockquote id="quote"> -> Your '98 Xantia has the 2port HP pump, reputed to be a bit slow on charging the suspension after long time parking.
If the reservoir has clogged (dirty) filters, you'll get even longer charge times, as the pump then cavitates.
The "choppy" rear is a bit hard to interprete ?
You mean hard suspension ?
- or you mean too soft suspension with bouncing up/down rear ?
If the rear suspension feels hard, then most likely still air in rear suspension, removed by Citaerobics. Should be done every 1-2 months regularly, to vent air/gas and to keep linkages moving.
If the rear suspension feels too soft, then try the corner bounce test on rear, both with engine idle, and after a while when engine stopped.
Reason is that the anti-sink sphere is connected as an extra suspension element with engine idle and system pressure present.
If this is ok, you should have slightly softer suspension with engine idle.

sandancer · Unread post by **sandancer** » 06 Apr 2004, 00:31

Hi Anders,
The spheres are all brand new. Sh** does happen, as I had one implode almost immediately it was pressurised. All the gas escaped throuth the hydraulic system and caused the LHM reservoir balloon somewhat!
The filters are clean.
Choppy - at speed, the ride is pretty smooth, but not perfect. At slower speeds, every small bump seems to come through, but it is not as bad as it was before the front spheres were replaced. As I've said, everything was OK for a fortnight after they were replaced.
As requested, tried the corner bounce test on the rear, both with engine idle, and after the engine stopped. Sure enough, the suspension is soft when idle, but when the engine is off, it is still pretty soft, but it goes down a couple of inches and stays there.
Pressure tick occurs regularly every two minutes.
I have carried out a series of other tests, this time sitting both on the front and rear and seeing what happens. First with the engine running, secondly immediately after turning it off, and finally about ten mins after turn off. First, it worked OK, raising the suspension within a few seconds. Second, it did rise a little (more at the front than rear) but very slowly. Finally, it just didn't rise at all.
I'm starting to suspect, like Robin, the Acc. sphere now.
Mark.

sandancer · Unread post by **sandancer** » 08 Apr 2004, 01:20

Sorted - See bottom of first post.

AndersDK · Unread post by **AndersDK** » 08 Apr 2004, 02:52

This is a bit odd [;)]
As the ticking interval was in fact pointing to a good acc sphere.
BUT : if the ticking interval was tested with suspension set to low, then you should have got frequent ticking. Reason is that the suspension circuit pressure feed is then closed off by the HC's, hence the suspension spheres can not function as pressure accumulators.

sandancer · Unread post by **sandancer** » 08 Apr 2004, 14:39

Possibility. One to keep in mind if...

French Car Forum

Suspension Conundrum - Sorted :-))

Suspension Conundrum - Sorted :-))