Leaking rear electrovalve

shaker · Post by **shaker** » 01 Apr 2007, 19:16

Went out to my 1999 Xantia 2.0 16v Exclusive Auto today and found a pool of the green stuff under the back end. Got my head under and I could just about see that the LHM was dripping from the rear hydractive unit, so got the car up on axle stands and removed the spare wheel carrier and crawled under.

Wiped everything clean and then added some more LHM to find out where it was leaking from and by using an inspection lamp and a mirror I was able to pinpoint the leak at the base of the electrovalve where it joins the main hydractive unit.

Did a search of the forum and came up with this from NiSk, which was extremely helpful, especially Mandrake's pictures:- http://www.frenchcarforum.co.uk/forum/v ... ctive+leak

A few questions:

1) NiSk mentions unplugging the HA computer to see if the leak stops - can someone tell me where the HA computer is located so that I can try this?

2) The car recently stiffened up at the back end and I was about to check the height corrector / plastic arm etc. Is it likely that excessive hydraulic pressure has caused the electrovalve to leak, or could a faulty electrovalve have caused the hard ride in the first place?

3) If the electrovalve itself is still ok, can it be re-sealed onto the main hydractive unit?

Thanks

DickieG · Post by **DickieG** » 01 Apr 2007, 19:56

The H/A computer is located within the box behind the O/S/F headlight. Its the one with two plugs into it, the large single plug connects into the engine ecu.

A faulty electrovalve can cause a firm/hard ride if it locks in firm mode because it then isolates the central Hydractive sphere which makes a significant contribution to ride confort.

shaker · Post by **shaker** » 01 Apr 2007, 20:00

Thanks for the swift reply DickieG, I'll try unplugging the HA computer now I know where it is.

bernie · Post by **bernie** » 01 Apr 2007, 20:17

There is a green 'O' ring under the valve which may be leaking.
Unfortunatly when I removed my rear valve it snapped in two as it's very soft alloy.
I bought a new one (£104+) and bought a few s/h ones just in case.
The HA ECU has 1 white and 1 black plug(s)

Mandrake · Post by **Mandrake** » 01 Apr 2007, 20:40

shaker wrote:A few questions:

1) NiSk mentions unplugging the HA computer to see if the leak stops - can someone tell me where the HA computer is located so that I can try this?

It shares the same box with the engine ECU. But you shouldn't really unplug it's connectors without first disconnecting the battery, so by far the easiest way to disable it temporarily for testing is to pull its fuse in the under bonnet fuse box. Just check your owners manual to find out which one it is, as it does vary with years and models.

The whine from the front electrovalve is quite loud with the bonnet up and a door open so you should be able to tell when you've got the right fuse.

2) The car recently stiffened up at the back end and I was about to check the height corrector / plastic arm etc. Is it likely that excessive hydraulic pressure has caused the electrovalve to leak, or could a faulty electrovalve have caused the hard ride in the first place?

"Excessive pressure" can't be the cause of the problem, because the electrovalve always operates from the full maximum system pressure (170 bars) more likely is that the electrovalve has failed for some reason and because of that failure the rear is now stuck in hard mode.

(Also remember that a completely flat/punctured hydractive centre sphere will give exactly the same symptom of being stuck in hard mode)

3) If the electrovalve itself is still ok, can it be re-sealed onto the main hydractive unit?

Well there are 3 seals in an electrovalve - two external green ones and one internal black one. Refering to this picture:

You can't see it, but just to the right of the thread is a large seal in a recess groove - this is the one that must be leaking if it is leaking around the base. The small green one near the end is pretty important to the functioning of the valve too.

The other place its likely to leak is on the overflow return hose - this is the rubber hose that attaches to the right hand stalk - and like all such rubber hoses they can get hard and brittle and begin to leak with age, so if it looks worse for wear and there is enough length try trimming it back a cm or so and fitting a new jubilee clip.

Regards,
Simon

bernie · Post by **bernie** » 01 Apr 2007, 20:46

Have you bought a new valve aswell Simon?

Mandrake · Post by **Mandrake** » 01 Apr 2007, 20:54

bernie wrote:Have you bought a new valve aswell Simon?

No thats your picture bernie.

I bought one second hand valve nearly a year ago to fix the excessive leakage problem the front electrovalve originally had. So far no excessive leakage has returned although I feel like the ride might be sticking in hard mode occasionally. (Hard to tell until I get to the bottom of the pump's woes)

Regards,
Simon

bernie · Post by **bernie** » 01 Apr 2007, 21:01

Mandrake wrote:
bernie wrote:Have you bought a new valve aswell Simon?
No thats your picture bernie.
Regards,
Simon

I'll tell you Simon, don't get old. That's my 55 year old brain dying.

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