XM Newbie

[Dieselman]

Not sure why the Lhm reservoir level affects anti-sink. I wouldn't necessarily suspect the anti-sink valves to be the culprit for sinking, but would check the amount of fluid flowing from the front and rear Hydractive electro-valves. Pull off the return pipe and observe fluid flow. There should only be a squirt as the valve changes state, continuous flow indicates internal leakage, which depending on the state the valve is in, is either the pintle seat is worn, or more likely a rubber O ring has split.

There are two bulletins relating to Hydractive-2 rapid sinking and slow to rise, in the Hydractive training material thread viewtopic.php?f=13&t=10291

Member, xantia_v6 would probably be best to advise on whether the electro-valves can be removed from the stiffness regulators without either subframe, or hydraulic block, removal.

If the sunroof fault isn't the actual switch, or connections then the roof unit needs servicing, which means removing the cassette from the roof.

The glass cartridge is adjustable for height, but the issue is the complete cassette will have sunk on it's mounting brackets. Sunroofs are heavy.

[EasyRider]

Thank you for the fast response Dieselman

[Biggles1957]

Don't forget you need to check the level with the engine running and suspension at high. If you check it any other way the reading will be miles out and appear to be over filled!

[xantia_v6]

Thanks for the replies.

Few issues:

1. The car is S2 but tends to sink overnight. No obvious leaks of LHM.

As far as sinking is concerned, the front and rear suspension are totally independent of each other, can you be a bit more specific of the symptoms? Is it settling right down to the bump stops overnight?

A leaky electrovalve should not cause sinking (assuming that the hydractive valves are the original type), as the electrovalve is supplied from the primary circuit before the antisink valve.

[Dieselman]

A leaky electrovalve should not cause sinking (assuming that the hydractive valves are the original type), as the electrovalve is supplied from the primary circuit before the antisink valve.

I used to think that, however there is a Citroen bulletin referencing exactly that issue, saying it is leaking electro-valves. (Attached)

Another item to check would be the brake Doseur valve isn't sticking slightly activated, allowing primary system fluid to return to the reservoir. We had a member with a rapidly sinking front end caused by the Doseur valve.

Checking the return pipes for flow will reveal the culprit.

Rapid sinking.pdf

Hydractive slow to rise.pdf

[xantia_v6]

I think that the first linked document is misleading, the "especially if the vehicle is not equipped with anti-sink suspension" seems rather ambiguous. It would not be the only time that a Citroen tech writer glossed over details that he didn't fully understand.

The electrovalve definitely gets is feed from the main supply. I have had Xantias with very leaky electrovalves (the needle valve not a broken o-ring) which did not sink, they were just very reluctant to open the hydractive valve.

The modified hydractive blocks as fitted to late Xantias do have the electrovalve fed from the suspension circuit, and (for a couple of reasons) they are more inclined to sink over the course of a few days.