Xantia sinking front end

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aerodynamica
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Xantia sinking front end

Post by aerodynamica »

Hello!

My 1993 Xantia has begun sinking very quickly at the front after parking. I traced the fault to the fron t hydractive firmness regulator.

Doses anyone have experience of this? I am sure I read about it once many years ago. I am wondering if there's a cause such as a valve seat or other that can be repaired?

I created a request in the wanted section for a replacement firmness regulator, if for anything to have a temporary item to fit while the faulty one is investigated.

Any help greatly appreciated!

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GiveMeABreak
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Re: Xantia sinking front end

Post by GiveMeABreak »


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white exec
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Re: Xantia sinking front end

Post by white exec »

Hi Graeme,

The regulators are not that complicated inside: essentially a shuttle valve, moved one way (firm) and the other (soft) by hydraulic pressure from the sphere, and the system (via the Electrovalve), respectively. The EV is also a simple mechanism, but careful how you unscrew it on its fine (aluminium) thread.

A page from the HA Evolution (new-type regulators) document, showing original type valve innards:

Click to enlarge
Original HA regulator design.JPG
Most likely just the EV solenoid not operating properly; might just be dirt. Worth taking that out first.

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xantia_v6
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Re: Xantia sinking front end

Post by xantia_v6 »

I think that it is only the electrovalve that can leak, not the main hydraulic valve, and it is a lot easier to change only that.

I have only experienced electrovalve leaking when energised, Does yours leak when not energised?

viewtopic.php?p=232209#p232209 may be relevant.

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white exec
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Re: Xantia sinking front end

Post by white exec »

Leak can be detected by seeing what emerges from the low-pressure return pipe at the end of the EV.
Normally, very little emerges from this.

Diode failure could, I suppose, prevent the EV solenoid from working fully (i.e. proper pull-in). Easy enough to strap on an extra diode (band on diode to +ve) to test.

There's a small spring in the EV too, which is there to close it when de-energised. Could be weak, or need a gentle stretch.

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Re: Xantia sinking front end

Post by aerodynamica »

Thanks chaps - all geat info. It leaks when the solenoid is energised and less so when it is closed but still when closed. You can see the main difference in the PRV cut in/out times comparing it with the EV open, closed, low suspension, normal and high. There's a marked difference but the PRV is cycling way too fast at best anyway (has a new accumulator sphere too). Getting 4 seconds on normal height, 8 seconds with EV closed and about 21 seconds with it on low.

I didn't think of the spring - good call Chris.

Interesting about the diode possible fail, never felt any of my 3 hydractive cars (XM Mk1, XM 1.5 , Xantia Mk1) had failed with the diode problem but perhaps I didn't realise...

Thanks Marc, I didn't realise Chevronics covered later models - that's good to know.

I'll report back on my findings!