Xantia - Hydractive 2 solenoid internal leakage ?

Mandrake · Unread post by **Mandrake** » 24 Nov 2005, 08:05

Hi Everyone,

On my continuing quest to iron out all the bugs in the suspension of my Xantia I've found yet another small (?) problem which I wonder if anyone else has. (Even if they don't know it yet

)

While working under the front of the car recently I noticed a hissing noise from the area of the pressure regulator after turning off the engine... after a bit of investigating I realised it was coming from the front hydractive control valve unit.

It seems that any time that it is activated, there is a significant amount of continous leakage from the HP inlet port (used to activate the control valve) to the overflow port. For those that havn't looked at the diagrams, its a double ended tapered needle valve operated by the magnetic field from the solenoid coil.

In the rest condition it blocks the HP inlet at one end, and opens the overflow end, and in the active condition the HP inlet opens and the overflow end is supposed to seal. It seems that the overflow end is not sealing 100%, most probably due to either wear, or particulate matter or grit fouling the seat.

Since I recently changed the oil and the old oil was full of grit (as well as being some kind of ATF) and I also recently cleaned the same grit out of the front height corrector it also seems likely the HA valve has the same problem and needs a good clean out.

One symptom of this leakage that I hadn't put 2 & 2 together about until now is a regulator cycle time that is excessively short despite a good accumulator sphere.

With the original flat accumulator that came on the car the cycle time was 15 seconds, and after replacing it it went up to 45 seconds, better, but by no means ideal.

Timing it recently I noticed the cycle time was back down to 18 seconds again, even though the accumulator still measures spot on 62 bars. After discovering the hissing of the valve I tried disconnecting the cable to the valve and timing the regulator cycle time - bingo, 3 minutes 45 seconds

(I should point out disconnecting the cable will cause the computer to de-activate the rear solenoid too)

So, HA2 valve disabled - 3 minutes 45 seconds, enabled, 18 seconds. Clearly there is significant leakage going on here, especially if its enough to hear hissing coming from it when listening close by.

Does anyone else want to try this test on their Hydractive 2 model to see if it happens to them too ?

Next time you have the front of the car up on stands, after running the engine turn the engine off, and then put your ear under the area of the regulator and hydractive control block and see if you can hear any hissing that stops when the solenoids shut off 10 seconds after closing the doors...... any audible hiss is a significant leak.

The other thing to try, much easier and probably more conclusive, is to measure the regulator cycle time with the Hydractive 2 computer fuse removed, or just unplug the cable going to the front valve as I did, and compare the time to when it is connected as per normal. A large difference in the cycle time indicates leakage.

I can see a number of potential side effects to this leakage, especially if the amount of leakage is variable. (As would be the case with grit stuck on the needle valve seat)

* Pressure regulator cycling frequently despite a good accumulator

* The "popping up in the air" effect some people get (including me) when lowering the suspension from the full height to normal height - caused by less than full pressure being available on the control side of the valve to force the valve into soft mode against the full suspension pressure

* The "dropping at the back after lifting" effect some people get (mine does it occasionally) where while lifting in the morning it lifts at the back, then the front, and THEN the back drops (HA valve opening) and lifts again. (Again due to a pressure drop on the control side of the valve)

* Height not correcting back down after getting out of the car unless you get out pretty quickly (after turning off the motor the accumulator pressure is quickly bled away causing the anti-sink valves to be shut, especially if you leave the doors open for a while before getting out)

* Possibly longer than usual lifting time due to some of the pumping action of the pump being wasted by the leakage. (And the 6+2 pump doesn't have much output to begin with.....)

* Potentially intermitant harsh ride as the hydractive control valve may not stay reliably in the soft mode when it should, if there is much less than full pressure on the control side of the valve a large bump (causing a pressure increase on the other end) may be enough to cause the control valve to move partially towards the hard state during the ride over the bump...(speculating a bit on this one...)

Any comments ?

Regards,
Simon

Unread post by **RichardW** » 24 Nov 2005, 09:16

Simon,

Yes, I get a hissing noise just after turn off from the front hydractive valve, and yes my car suffers from all the symptoms you have listed

There was a regular fault on early hydractive cars where (I believe) an internal O ring in the hydractive block failed, which caused the cars to sit right down a few seconds after switch off - the anti-sink hides this I guess, but the cause seems to be the same. I understood the O-ring could be replaced, but I have never seen anybody say this conclusively, nor seen any parts quoted - I'll have a look on pr.net and see if anything is obvious.

Unread post by **RichardW** » 30 Mar 2006, 13:13

Simon,

Thought we'd work on our own thread, instead of hijacking someelse's thread 8)

Whilst considering whether I should punt my VSX TD on, I realised there's not actually that much wrong with it. OK the temp sensor for the climate control is wired to front of the dash, and I'm probably going to have to change the matrix in the summer

, but it does have this erratic suspension behaviour that's starting to annoy me (only took 30k miles

).

Now there have been several threads, so I've read through most of them. I defo have a leak on the front hydractive unit (hiss after swtich off, sunk at rear, long time to repressurise after stopping). Now, the unit is in 2 parts - the hydractive block (costs £300) and the electro valve (about £100). From discussions, it seems that the leak is in the electrovalve and not the hydractive block. Is this your thinking? I might be tempted to buy a new electrovalve (unless I can get a S/H one from a rear unit) if that's the case. How easy is it to get the valve out?

What is your thinking on whether there might be problems in the hydractive unit itself? I changed the LHM at about 75k miles (hydraflushed) - what came out was pretty dirty, but not that bad. Pretty sure it had never been changed as I had to cut some cable ties on pipes to get the tank out!

Mandrake · Unread post by **Mandrake** » 30 Mar 2006, 21:34

RichardW wrote:Simon,

Thought we'd work on our own thread, instead of hijacking someelse's thread 8)

Whilst considering whether I should punt my VSX TD on, I realised there's not actually that much wrong with it. OK the temp sensor for the climate control is wired to front of the dash, and I'm probably going to have to change the matrix in the summer , but it does have this erratic suspension behaviour that's starting to annoy me (only took 30k miles ).

Can you describe the erratic behaviour ? As time goes on mine seems to be getting even more erratic...

Now there have been several threads, so I've read through most of them. I defo have a leak on the front hydractive unit (hiss after swtich off, sunk at rear, long time to repressurise after stopping).

What about the pressure regulator cycle time ? If its really short despite a good accumulator sphere (mine is between 8 and 15 second with a NEW accumulator sphere) then there is high leakage. You can confirm if its the valve by the following test:

Time it with the car idling under normal conditions. Presumably you will have a short cycle time. Now (with the engine off) unplug the 2 pin plug going to the front electrovalve, and plug a 47 ohm 10 watt resistor into the plug.

Start the engine again, and do a quick bounce test to confirm that the front end is in the hard mode but the rear end is still in the soft mode. Now time the cycle time. If its MUCH higher (lets say, 1 minute) then that means most of the leakage is from the front valve, and not much if any from the rear one.

Now unplug the resistor and confirm with a bounce test that the rear is now hard too, and time it again. If you don't get much change this time the rear is ok. If you can tell me those 3 timings we can figure out where the problem is with reasonable certainty.

When doing each of the timings make sure you allow the pressure regulator to cycle at least twice, and take the last reading, as the first one will be shorter.

Now, the unit is in 2 parts - the hydractive block (costs £300) and the electro valve (about £100). From discussions, it seems that the leak is in the electrovalve and not the hydractive block. Is this your thinking?

Yes that is definately my experience with my car. I took the entire units out and examined and cleaned them, checked them with compressed air etc, and I concluded that there was nothing wrong with the main hydractive blocks, nor could there be anything wrong with them that would cause the leakage symptoms, as there is no path for the leakage to follow.

I might be tempted to buy a new electrovalve (unless I can get a S/H one from a rear unit) if that's the case.

Hmm, well a new electrovalve is still a lot of money, so you'd want to be pretty certain from the timing test above that it is the culprit, I'd still try getting a rear second hand one first if at all possible.

How easy is it to get the valve out?

While I didn't have any trouble, its a good idea not to remove it unless you have the replacement on hand if that is your daily driver, as there is apparently a small risk of breaking it internally when undoing it, if someone has over tightened it.

Basically you lower and depressurize the suspension completely (*and* the pressure regulator, since the electrovalve runs of the direct system pressure) then disconnect the rubber return hose on the top of the valve (and immediately block it off with a bolt unless you like all your LHM running onto the ground...)

Unplug the electrical plug.

The nut around the return output is 16mm, and you use a 16mm socket on it - its important to use a socket with a short (supported) extension so you can keep the applied torque square, a spanner is more likely to damage it.

It should then just unscrew without any drama. I found it pretty easy, the main problem I had is the moment you disconnect the return hose oil starts pouring out of it so its very difficult to prevent a bit of oil getting all over the place while transfering the pipe from where it belongs to being blocked and back.

You probably want a new small jubilee clip there too, as the original will be a crimp type.

What is your thinking on whether there might be problems in the hydractive unit itself? I changed the LHM at about 75k miles (hydraflushed) - what came out was pretty dirty, but not that bad. Pretty sure it had never been changed as I had to cut some cable ties on pipes to get the tank out!

As I mentioned above I think its extremely unlikely the main unit has a problem, and couldn't cause the specific symptoms anyway. Replacing the whole unit would be throwing money away...

Regards,
Simon

Unread post by **RichardW** » 31 Mar 2006, 07:44

>Can you describe the erratic behaviour ?

Loud hiss from the front hydractive valve 15-20 seconds after swich off (usually as you are walking away!), followed by the rear sinking to the bump stops. Front usually doesn't get a chance the correct downwards. At start up it takes ages for the light to go out, the front often comes down to start with, the rear comes up (takes ages!), and then the suspension runs in hard mode for the first 30s or so. When it swtiches to soft mode, the rear drops, then corrects back to right height. It seems to get stuck in hard mode sometimes (although this is much improved since the hydraflush). The cycle time is about 10s - even after I fitted a new accumulator. When sitting in traffic the front valve clunks a lot. Going from high - low or back I often get the jump in height. Going back to our discussion about heat affecting it - the symptoms are much less marked if the car has only been on a very short run (say a mile or 2) - in this case behaviour is pretty normal - height corrects a both ends, car stays up, light goes out in a few seconds. It still usually gives hard mode for the first while though. Maybe I should make a protective shield from the radiator from tin foil

Apart from this it's great!

I'll try unplugging it some time - no resistors hanging about. Pretty sure it's the front valve - the loud hiss gives it away! I'd be prepared to spend £100 on a new valve I think - scrapyards, and especially ones that contain VSX Xantias, seem a bit few and far between here in Scotland.

I had a look at the Citroen Technical Guide, and see that the only place the leak can be is the electrovalve, as there is no other return path to the tank. Now, if we could just work out how to refurbish them...!

Mandrake · Unread post by **Mandrake** » 31 Mar 2006, 08:11

RichardW wrote:>Can you describe the erratic behaviour ?

Loud hiss from the front hydractive valve 15-20 seconds after swich off (usually as you are walking away!), followed by the rear sinking to the bump stops.

Hmm, ok, the rear doesn't sink to the bumpstops on mine, but the symptoms of yours sound even worse than mine

you may have an additional problem as well as the electrovalve, but its hard to tell until this is sorted out first

Front usually doesn't get a chance the correct downwards.

Yes mine does this. If I turn off the engine and get out immediately it has time for the front to correct down, but if I turn off the engine, and wait about 30 seconds before getting out the accumulator pressure has already been bled away enough to close the front anti-sink valve and prevent the front height correcting when I get out, leaving the car standing too high at the front...

At start up it takes ages for the light to go out, the front often comes down to start with, the rear comes up (takes ages!), and then the suspension runs in hard mode for the first 30s or so.

I notice as the leakage with mine has got worse the time until light out has got worse. It used to be 8 seconds after standing over night before the hydraulic light goes out, now its up to 12 seconds.

When it swtiches to soft mode, the rear drops, then corrects back to right height. It seems to get stuck in hard mode sometimes (although this is much improved since the hydraflush).

Mine also sometimes sticks in the hard mode at the rear until I drive off down the road and it suddenly drops and re-corrects. Sometimes this happens as I'm backing out the driveway, or as the car is lifting.

When sitting in traffic the front valve clunks a lot.

Ok now this I don't get. Are you sure its the electrovalve ? I can't hear mine switching when the engine is even just idling due to the masking sound of the engine... are you sure thats not something else clunking ?

If it is the electrovalve you may have an electrical issue with it too, such as the internal diode being open circuit, (ala bernie) or an intermitant cable/plug fault.

Going from high - low or back I often get the jump in height.

Yep, I get that very frequently. When I attempted to clean the valve out when I had it on the bench (compressed air and petrol) and I managed to get it stop leaking for a while, it completely stopped the behaviour of popping up like a cork when lowering the height from maximum. Now that its leaking a lot again it does it nearly every time.

Going back to our discussion about heat affecting it - the symptoms are much less marked if the car has only been on a very short run (say a mile or 2) - in this case behaviour is pretty normal - height corrects a both ends, car stays up, light goes out in a few seconds. It still usually gives hard mode for the first while though. Maybe I should make a protective shield from the radiator from tin foil

Now that you mention it I think I notice a heat effect too. Many a time recently I've driven off down the road on a cold morning and thought "hmm, maybe the ride on this thing is not so bad after all" and yet by the time I get to my destination the ride is harsh, and there are obvious symptoms of the valve leakage.

Typically only 5-10 minutes driving before the ride goes from good to bad.

A little aluminium heat shield is not such a crazy idea, I might even make one up, if only to prolong the life of the replacement valve..

I'll try unplugging it some time - no resistors hanging about.

Ok, the resistor is to fool the computer into thinking everything is ok, without it it deactivates the rear electrovalve too.

Pretty sure it's the front valve - the loud hiss gives it away! I'd be prepared to spend £100 on a new valve I think - scrapyards, and especially ones that contain VSX Xantias, seem a bit few and far between here in Scotland.

Ok fair enough on the second hand situation... theres no doubt from your symptoms that at least one of the valves must be leaking heavily, and clearly the front valve is from the noise... what is unknown is the state of the rear valve, which may also have a small amount of leakage, but replacing the worst one of the two would be a good start.

I had a look at the Citroen Technical Guide, and see that the only place the leak can be is the electrovalve, as there is no other return path to the tank. Now, if we could just work out how to refurbish them...!

Yep thats right, there is no low pressure return or overflow from the main hydractive block.

When I replace my front one I'll be seeing if I can open up the old one and recondition it.... if it is indeed a stuffed o-ring I'll get a new o-ring, and try fitting it on the rear of the car...

I'll let you know if I succeed in opening it and reconditioning it..(or if I snap it in half trying

)

Regards,
Simon

Unread post by **RichardW** » 31 Mar 2006, 08:23

"now its up to 12 seconds. "

I wish! Engine idling, mine is more like 60 seconds. Even driving it takes 400m or so before it goes out. The valve dumps all the pressure from the system and the weedy 2 piston pump takes ages to pump it up again (think starting from flat).

"Are you sure its the electrovalve "

Pretty sure. Same clunk can be heard when the valve swtiches on/off when the doors are opened. It's pretty loud - this a TD remember, and I can hear it over the row of the engine, and all the sound deadening!

"such as the internal diode being open circuit"

Yeah, I was wondering about that - maybe the valve is shuttling back and forwards.

I'm leaning towards a new valve. Next month maybe - got to change the clutch in the ZX before it does my Wife's back in again!