Xantia rear suspension hydraulics

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davewithington
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Xantia rear suspension hydraulics

Post by davewithington » 12 Nov 2014, 10:26

I've noticed rather strange symptoms with the back end of my '97 Xantia over the past few months, so I'd appreiciate comments.

When parking up, say we've gone shopping, and my wife gets out,the back end rises, which is normal (less weight in the car, not that I'm saying she's fat ....), I switch off, and the suspension locks, as it does with a non-sinker. Put shopping in the boot, say a couple of bales of compost, get back in, start up, red lights go out and of we drive. After a short while, the back end drops with a light thump, so I reckon the anti-sink valve is sticking. Also, the back end is very slow to react when raising or lowering the suspension using the inside lever. What do you reckon Jim and Paul?

I've had Hydrorincage in the system, and nice clean Total LHM flowing through the pipes, and I believe the rear height corrector was renewed about four years ago

davewithington
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Re: Xantia rear suspension hydraulics

Post by davewithington » 13 Nov 2014, 11:16

Definitely isn't the sphere - I changed that last year(incidentally it improved brake response no end). Could be height corrector, but would this give me slow reactions, and I do mean slow. The front end is sitting around reading a magazine while waiting for the back end to catch up.

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Mandrake
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Re: Xantia rear suspension hydraulics

Post by Mandrake » 13 Nov 2014, 11:28

The delayed thump/drop at the rear won't be the anti-sink valve, they don't stick, and even if it did it would prevent the rear rising at all until it un-stuck.

It will be the rear Hydractive valve sticking in the hard mode, when it finally switches to soft there will be a pressure equalisation between the outer spheres and middle sphere which usually results in a sudden drop in height if you have added weight to the car, accompanied by an audible thump.

There can be a number of causes for this including a failing diode in the electrovalve unit, (has the car had the diode mod done yet ? If not, do it) a leaking needle valve in the electrovalve, or gunk in the hydractive control block itself. Anything that causes it to stick in hard mode when it should be in soft will give the symptom you describe.

In my experience of owning three Hydractive 2 Xantia's the first two did what you describe fairly intermittently for no good reason that I could find despite quite a bit of work on the suspension... unless it happens all the time it could be considered a bit of a "quirk" as they get older, although I notice that my current Xantia so far hasn't exhibited this quirk despite being the oldest (but lowest mileage) of the three.

As for slow height adjustments at the rear - if you mean that it lifts and/or falls very slowly compared to the front then that will be a seizing height corrector linkage for sure. What happens is the rust build up on the linkage restricts the range of motion - so the height corrector shuttle valve is never able to fully open. It can still correct the height but the flow rate is restricted by the partial movement thus it rises or falls slowly. My second Xantia had this problem but I never got around to fixing the linkage. It's also possible the height corrector itself is clogged up with muck and needs a strip down and clean out but the linkage being rusty or having an issue with restricted range of motion is much more likely.

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Re: Xantia rear suspension hydraulics

Post by davewithington » 13 Nov 2014, 11:33

Fair enough.I can live with the electrovalve sticking - it is more of a quirk at the moment, but I'll have it apart next time the car's on the lift, and yes the diode mod was done by a previous owner. I'll also have a look at the height corrector at the same time, pop the dogbone off and free it off.

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Dommo
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Re: Xantia rear suspension hydraulics

Post by Dommo » 13 Nov 2014, 15:43

Mandrake is spot on. My VSX does exactly the same Dave. It's characteristics depend on the pressures in the spheres - changing my main accumulator made the behaviour change, but the 'problem' is still there.

My rear electrovalve leaks in hard mode, so when the car is turned off, all pressure from inside the rear hydractive sphere leaks back to the tank. Once you turn the car on again, the pressure differences either side of the valve (because there is no LHM under pressure behind the electrovalve) cause the valve to stick shut. Eventually, certain circumstances make the valve open and the rear end drops to the floor while the pressure balances out. In my case it was whenever the rear suspension was compressed as the road started to go up an incline.

If my electrovalve didn't leak back to the tank I don't think this would happen, but having changed the electrovalve for 3 other spares - and doing the diode mod - I have given up trying to fix this 'quirk'. But since recently changing the main accumulator the valve tends to open before I've even left the driveway, and it no longer completly drops to the floor unless there is a lot of weight in the car.

It's a difficult thing to describe, so if this seems like garbled nonsense I won't be surprised!

My Activa used to have very good electrovalves. If I turned the car off at normal height and waited for the valves to turn off, then put the car to service low and opened the door, the car would jump up slightly as the pressure trapped in the hydractive sphere was allowed out to the corner spheres!

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Re: Xantia rear suspension hydraulics

Post by davewithington » 13 Nov 2014, 15:52

It doesn't drop to the floor, just a short drop, markedly worse when I have 10 bags of cement in the boot!

I'll leave it for now, now I know what it is

I'll have to try the bounce test myself

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Mandrake
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Re: Xantia rear suspension hydraulics

Post by Mandrake » 13 Nov 2014, 15:57

Dommo wrote: My rear electrovalve leaks in hard mode, so when the car is turned off, all pressure from inside the rear hydractive sphere leaks back to the tank. Once you turn the car on again, the pressure differences either side of the valve (because there is no LHM under pressure behind the electrovalve) cause the valve to stick shut. Eventually, certain circumstances make the valve open and the rear end drops to the floor while the pressure balances out. In my case it was whenever the rear suspension was compressed as the road started to go up an incline.

If my electrovalve didn't leak back to the tank I don't think this would happen, but having changed the electrovalve for 3 other spares - and doing the diode mod - I have given up trying to fix this 'quirk'.
That's rather unusual that 3 valves have the same problem - have you confirmed that it is actually the electrovalve leaking in hard mode by connecting a clear hose to a jar to the overflow spigot on the end ?

When you're changing Electrovalves are you using the same green o-rings each time or are you keeping the o-rings that came with the valves ? The only thing I can think of is if the small green o-ring near the filter gauze was leaking that would cause it to leak in hard mode but not soft mode...

The only other thing that might cause it would be if the needle valve was pitted or jamming, and that's very unlikely to be the case on all three...

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Dommo
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Re: Xantia rear suspension hydraulics

Post by Dommo » 13 Nov 2014, 16:53

Mandrake wrote:
Dommo wrote: My rear electrovalve leaks in hard mode, so when the car is turned off, all pressure from inside the rear hydractive sphere leaks back to the tank. Once you turn the car on again, the pressure differences either side of the valve (because there is no LHM under pressure behind the electrovalve) cause the valve to stick shut. Eventually, certain circumstances make the valve open and the rear end drops to the floor while the pressure balances out. In my case it was whenever the rear suspension was compressed as the road started to go up an incline.

If my electrovalve didn't leak back to the tank I don't think this would happen, but having changed the electrovalve for 3 other spares - and doing the diode mod - I have given up trying to fix this 'quirk'.
That's rather unusual that 3 valves have the same problem - have you confirmed that it is actually the electrovalve leaking in hard mode by connecting a clear hose to a jar to the overflow spigot on the end ?

When you're changing Electrovalves are you using the same green o-rings each time or are you keeping the o-rings that came with the valves ? The only thing I can think of is if the small green o-ring near the filter gauze was leaking that would cause it to leak in hard mode but not soft mode...

The only other thing that might cause it would be if the needle valve was pitted or jamming, and that's very unlikely to be the case on all three...

I haven't confirmed by using a hose like that, but I had noticed that the hose has been jubilee clipped on by a previous owner, suggesting it has been an issue for a while. And you can always hear it do the flushing toilet sound as the LHM leaks back to the tank after the valve closes.

I should clarify (now that I have remembered) that I have never managed to remove the entire electrovalve. While undoing the valve it has come apart every time, so I have been able to replace the innerds, but not the part the valve slug actually seals against. Which has led me to decide this was the problem, or if it wasn't the problem, the o-rings could be.

Without removing the electrovalve block completly, I am unable to get the electrovalve off, and I have decided just to live with it for now! Definitely very good suggestions though.

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Re: Xantia rear suspension hydraulics

Post by davewithington » 13 Nov 2014, 17:01

How's the Toyota doing Dom?

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Dommo
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Re: Xantia rear suspension hydraulics

Post by Dommo » 13 Nov 2014, 17:39

It has it's issues Dave, some of which are simple suspension alignment things (need a trip to Kwik Fit I think..), and some are harder to fix. I need to get some bits together to be able to regas the struts, they don't have as high a pressure as a Citroen sphere, so you'd think it would be easy enough but I've not come up with anything yet.

There's a big following in Australia and there's a bloke down there who has rebuilt the nitrogen accumulators with better seals, but they're around £1000 PLUS delivery. And he would want my old ones in return. So I'd like to do something similar but over here in sunny Stoke!

There is a blog thread of mine on here somewhere!

How is your new automatic VSX doing? Apart from this suspension quirk of course.

davewithington
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Re: Xantia rear suspension hydraulics

Post by davewithington » 13 Nov 2014, 17:53

Still a delight Dom, though I want to have the bonnet and tailgate painted in the Spring, cost me about £600

I have an oil leak from behind the block which could be the normal leaking head gasket, but my chap in Crewe thinks it's something else. I will investigate sometime, when I have the inclination

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Re: Xantia rear suspension hydraulics

Post by Dommo » 13 Nov 2014, 18:08

Sounds great! What sort of fuel economy are you getting from it Dave?

Shame about the leak, on the XUD engines the cam cover gaskets love leaking, is it as simple on the 2 litre engine?

davewithington
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Re: Xantia rear suspension hydraulics

Post by davewithington » 14 Nov 2014, 09:48

I don't ever think about fuel economy - I used to run 4.2 ltr Jags, so anything better than 14 to the gallon is a bonus. I probably get around 35 on a run, a lot less round town but I do enjoy the step off you get with a torque converter auto, very addictive. You'll have to have a drive.

The leak ain't the cam cover gasket, that was the first thing I changed.

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CitroJim
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Re: Xantia rear suspension hydraulics

Post by CitroJim » 14 Nov 2014, 14:34

Dave, for the oil leak check the turbo feed and return hoses. The return hose especially is rubber and can perish...

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Re: Xantia rear suspension hydraulics

Post by davewithington » 14 Nov 2014, 15:41

Not mine - non turbo 8 valve