Xantia doseur valve

mark21td · Post by **mark21td** » 26 Sep 2009, 11:54

Where is it ?

Post by **CitroJim** » 26 Sep 2009, 12:11

Hi Mark

It's just behind the brake pedal and it can be seen from the engine bay.

In turbo models it's fairly well hidden by the turbo pipework.

Picture below shows it. The green arrow...

What's the problem?

Clogzz · Post by **Clogzz** » 26 Sep 2009, 12:11

High up the firewall in the engine room, opposite the brake pedal that operates it.
It looks like a small barrel, about 2 inches across, with a big circlip; item 71 in the picture, holding the insides in.

mark21td · Post by **mark21td** » 26 Sep 2009, 15:02

I need to change the rear sphere's on my 97 1.9td VSX estate (hydroactive) that I've just brought.
I've now found that it needs to be done in different way but don't know how (no manual yet).

Post by **CitroJim** » 26 Sep 2009, 15:57

Ahh right, yes the method of changing rear spheres is a little different.

All fully explained here, in the sphere changing sticky.

Make sure you carefully follow and observe the safety precautions with regard to supporting the vehicle when working underneath.

Good to hear you now have a VSX estate

Nice.

Luckily the dosuer will not feature in any sphere changing jobs...

mark21td · Post by **mark21td** » 26 Sep 2009, 16:14

Jim where is this
"depressurise by opening the 12mm bleed valve on the pressure regulator by no more than half a turn and go back,"

Post by **CitroJim** » 26 Sep 2009, 16:25

Look at the front of the engine Mark, near the gearbox and you'll see the accumulator sphere . Look aat the block it's screwed into and there you will see it. The bleed screw is the only 12mm size on the whole car virtually.

This picture shows it on an Activa but a 1.9TD is almost identical here.

Only undo the screw about half a turn and no more.

Strictly, it's not really necessary to depressurise to change spheres. As long as the suspension is on low, there'll be little residual pressure left and on the V6 I never do because this screw is so hard to reach!

Open it, on a hydractive, on low and with the engine still running.

mark21td · Post by **mark21td** » 26 Sep 2009, 16:41

My car is rides very hard, mostly at the rear I think whth is why I've only get new ones for the rear (abit scint at the mo).

Oh and mine is also an Athena.

Also what do the verieus sphere's do, There's 7 (3 up front and 4 at the rear) and they must all have a function but I have no idea what each one does.

As you can tell I'm very new to citreons.

Post by **myglaren** » 26 Sep 2009, 17:13

This doesn't really explain the functions of each individual sphere but is an excellent manual on how to service the whole hydraulic system including sphere changing.
Sphere Changing

Here is a bit of Basic info on a standard Xantia.

Some more

More

Well worth a look as it explains the DS system Part !!.

More later.

Post by **CitroJim** » 26 Sep 2009, 17:44

To get a really good understanding of how the hydraulics work, there is no finer reference than the Citroen Technical Guide. Download the PDF and really have a great read!

A hard Hydractive car may not be spheres. It's more than likely a problem in the suspension electronics or stiffness regulator electrovalves.

I recommend a Lexia session initially to diagnose any basic issues. You may well find you need to do the "Diode Mod" on the electrovalves to restore normal operation of them.

It sounds like yours is stuck in hard mode and hard mode is really hard. Hard mode is the default and failsafe mode in case of failure of the electronics and electrovalves. Soft mode is the mode the car will spend by far the majority of time in when driving; hard mode comes in when flying around corners, accelerating away and braking hard.

Have a look at the Activa Buyers Guide and here, as long as you ignore the Activa-specific bits you will find the method for testing the hard and soft modes of the hydractive suspension.

On a hydractive car, the corner spheres are only fully effective in hard mode and do little in soft mode. In soft mode, most of the word is done by the hydractive centre spheres. The front one you will find nestled agains the radiator and the rear one hanging down at a jaunty angle toward the front of the rear subframe.

mark21td · Post by **mark21td** » 26 Sep 2009, 19:36

Yes it does sound like it's stuck in hard mode, it goes up and down as it should (I think) but there's a buzzing sound (sounds like an electric motor or fan) from under the rear of the car when the ignition is turned off, this sometimes stops after 2 mins but has still been buzzing after 30 or more, is this normal ?

Post by **CitroJim** » 26 Sep 2009, 20:41

The buzzing you can hear Mark, is the sound the hydractive stiffness regulator electrovalves make when switched to soft mode. That you can hear it is a good sign but no assurance whatsoever that they are working as they should.

You'll hear the sound for up to thirty minutes with any door open and the ignition off. It'll stop after thirty minutes despite a door still being open to conserve the battery.

If all doors are closed, the buzzing should continue for 30 seconds after closing the last door. It will recommence on opening any door.

With the ignition on and the engine running, the valves will buzz although you'll have trouble hearing it.

The buzzing is used as a basic indicator of functionality. If all is well, opening a door (with ignition off) you should hear the electrovalves operate to soft mode with a distinct clunk followed by the buzzing. On closing a door and waiting thirty seconds you should then hear the valves clunk solidly off and the buzzing cease. The clunk will be louder if this test has been performed shortly after switching off the engine whilst residual pressure remains in the hydraulic system. If you do not hear these clunks at the beginning and end of the buzzing, this often shows the need for the "diode mod" to be performed. The diode mod replaces failed diodes internal to the valves; their function, in a nutshell, is to ensure the valves operate full and remain fully operated until they are commanded by the ECU to switch off.

Hydraulic pressure plays a significant role in switching into soft mode. If the pressure is low because of say, a flat accumulator, the electrovalves will not properly switch and hard mode will remain selected. Check your accumulator by listening to the tick rate from the pressure regulator behind it. The tick interval should be in excess of 30 seconds. The ticking you hear is in fact the pressure regulator switching in and out like a thermostat to maintain a constant system pressure of around 170 Bars. Very rapid ticking indicates a flat accumulator sphere or very high internal hydraulic leakage somewhere in the system.

mark21td · Post by **mark21td** » 27 Sep 2009, 10:14

I'll check for the clicking today but from memory it's clicking much faster than 30 seconds, so this could be quite an easy fix then

DickyG is going to plug it in to his Lexia unit next week hopefully, unless I can sort it before hand.

I'll drop off the Lucas EPIC while I'm there.

Post by **CitroJim** » 27 Sep 2009, 11:46

mark21td wrote: I'll drop off the Lucas EPIC while I'm there.

Excellent

Thanks Mark, looking forward to getting to grips with one of those!

mark21td · Post by **mark21td** » 27 Sep 2009, 11:57

Right, I've been out and checked things over,

There is a distinct clunk when the buzzing stops, so thats a good sign, but it goes on for about 10 mins after opening then closeing a door.

As for the accumulator it clicks every 11 seconds, so I'll change that on monday when GSF are open (I haven't done anything with the rear units yet so I'll get my money back on them).

The LHM fluid looks a bit brown so I'll flush the system with new oil.

Ps. I get trade at GSF as I'm in there so oftern