XM 94; Hydractive Suspension

[Macvettexm]

94 XM 2.0: Auto, Hydractive. All new spheres,all new LHM, clean filters, started to have heavy steering and now will not raise. Driving great for a year and a half and now nothing. Help please.HP changed and primed.No use. Thanks in advance.

[Dieselman]

Try twisting the suction hose on the reservoir and pump spigots, if it can twist at all it will be drawing air in. Colder ambient temperatures cause the hose and spigot to contract so the clamp has less force.
Tighten the clamps sufficiently to stop air leakage. If the clamps are the original Ligarex banding, turn the pin to tighten the clamp.
If necessary, add rubber strip under the hose clamps to ensure all round clamping force.
If the hose is tight suspect a crack in the pickup pipe into the reservoir.

After ensuring the hose isn't drawing air, loosen the 12mm bleed bolt on the regulator 1/2 turn and run the engine for 1 minute to allow the pump to draw fluid unrestricted, then tighten the bleed bolt. The pump isn't self priming from completely empty, so if pumping against a pressure head, can't compress the air, so can't suck in fresh fluid.

As an absolute test of whether the pump is drawing fluid, disconnect the suction hose from the reservoir, fill the hose with fluid and watch to see if the pump sucks it in.

If the fault is definitely not air being drawn in it is possibly either the regulator, or Flow Distribution Valve (FDV) constantly returning fluid to the reservoir. I don't think this is likely, but can be checked by checking the return flow back to the reservoir.

Your car is fitted with H2 suspension, so it's possible one of the electrovalves is returning a high quantity of fluid due to a split O ring, or damaged seat.
Again, pulling the return pipe should reveal high leakage.

The information you need it in this linked thread. viewtopic.php?f=13&t=10291

There are two bulletins in the linked thread, one is for rapid sinking after switch off, which is possibly a damaged electrovalve seat, the other is slow to rise, which is a split O ring on the electrovalve, allowing fluid to return to the reservoir constantly.
If fluid constantly returns when the system is de-energised, the pintle seat is defective, if when energised the O ring is split. Try forcing hard mode by pulling the fuse and see if the car lifts.

Theoretically, the steering , or doseur valve could be leaking back sufficiently to cause lack of pressure, but I think that is unlikely, especially for sudden failure. Checking the return flow will give a definitive answer.
See layout diagrams for return pipes. The diagram in the previously linked to Hydractive thread is clearer, but is for Hydractive 1, so only a single electrovalve.

Please see link to thread where we had discussion regarding a car rapidly losing height, thought to be the electrovalve, but turned out to be the brake doseur valve bell crank being stuck so not retuning to off/closing the feed port. viewtopic.php?f=7&t=10695

Start with the basics, ensure the pump is actually pumping fluid, then check the returns to see which is leaking back constantly. What may initially seem like a difficult problem will turn out to be something very simple.

[Macvettexm]

Thank you Dieselman.Much to do and learn.Aidan.