Leaking rear hydractive unit

NiSk · Post by **NiSk** » 15 May 2006, 16:07

The car in question is an XM 2.5 TD Break, 1998 - but I imagine from other forums that the fault is typical of Cits fitted with HA II. I have an LHM leak which appers to be coming from the hydractiv control unit that is bolted to the middle of rear axle crossbeam. The LHM is dropping from both sides of the bracket on which the hydractiv unit is bolted. Even with the spare wheel, spare wheel tray, heat sheild and cross silencer removed, its a pig to get at, and most of my observations have been made with mirrors (from a grease pit).

I have read of the other peoples problems with the solenoid valve associated with the above mentioned iron clump. (iron/aluminium combination?)
Does anyone here have a pic showing where this valve fits, since the pics in Citroëns spares list are no use whatever. I just wondered if anyone has a loose rear axle lying about that is easy to photo.

//NiSk

andmcit · Post by **andmcit** » 15 May 2006, 16:20

NiSk wrote:I just wondered if anyone has a loose rear axle lying about that is easy to photo.

//NiSk

Yep, literally lying around...in the rain...and in 100% working condition...well, it was...

Thing is, it's predictably raining here in South Wales at the moment!! [Nothing new there then - land of the leek

]

When it clears I'll take plenty of pics and post them here.

Andrew

NiSk · Post by **NiSk** » 15 May 2006, 16:31

Thanks a bunch Andrew!

Despite the fact that the hydraulic pipework looks 100%, I have about 15 years experience of hydraulic Citroëns, and know that if I start disassembling it, something will break, and I'll be stuck there with no transport . . .

//NiSk

Mandrake · Post by **Mandrake** » 15 May 2006, 20:47

I know this is probably stating the obvious, but as with any LHM leak, the only way to find it is to thoroughly clean the oil off so that when it begins leaking again you can identify where its leaking.

There are several possible leaking points - there are two standard 3.5mm pipe unions with rubber seals, there is the low pressure overflow rubber line which is connected to the end of the electrovalve, and there are the two 10mm pipes from either side - which are flared type fittings with NO seals.

There is also a seal between the electrovalve and the main hydractive unit body, but I think its quite unlikely for that to be the leak.

The hydractive unit is quite robust by the way so you're unlikely to damage it or find a problem with it, however the electrovalve is a bit more delicate, so if you did remove that from the main unit you'd want to be careful.

(Fortunately you don't HAVE to remove it on the rear unit... on the front unit you have to remove the electrovalve before you can remove the main unit

)

The first one I'd check is the low pressure overflow line - if you can turn it the clip is probably loose - replace it with a jubilee clip.

By the way, I wouldn't say its THAT difficult to get access to, its actually easier to remove than the front unit. I just remove the spare wheel carrier and drive the rear of the car up onto ramps and even with the suspension right down and depressurized theres enough room for me to sit under the car. So while its not a walk in the park, its not that difficult either...

Regards,
Simon

NiSk · Post by **NiSk** » 15 May 2006, 22:32

Hi simon,

I'm afraid that I'm talking about an XM here, not a Xantia, and the rear hydractive control unit is a real pig to get at. I've seen some pics taken froma Xantia on our Swedish forum:

http://forum.citroenakuten.com/viewtopi ... highlight=

(just ignore the words and look at the pics) it shows a corroded electrovalve (which seems to be quite a common problem over here- probably due to the enormous amount of salt used in the winter). It also shows how much room there is on a Xantia.

I've been under the XM in a grease pit and even with the spare, spare carrier, heat sheild and transverse silencer off, I couldn't get my smallest digicam in place to take any pics.

What I can see is that the two hydractive pipes are OK, the large overflow pipe is OK, the 3.5 mm pipes to/from the height corrector are Ok (using a mirror after blasting off all the gunk with an air line) and the thin transparent overflow pipe is also OK. However, I can't even see the electrovalve and the LHM is seeping down both sides of the bracket to which the hydractive control unit is bolted. I'm very much inclined to believe that I've got the same problem as the guy with the Xantia pics.

I'm hoping that someone has a pic showing the exact location of the electrovalve and can tell me how to get it out!

Many thanks for your comments.

//NiSk

andmcit · Post by **andmcit** » 15 May 2006, 23:10

Right NiSK.

Light was rubbish this evening so the pictures will have to be retaken again in proper daylight tomorrow...

may try to get a decent focus of things next time too!!

This is pretty much how it's looked since I dropped it to the floor! It all looks as though it's been at the bottom of a river bed for years but underneath an Xm is the nearest thing...

Here it is from the middle to right hand side top...

looking towards the height corrector...

More to follow, hope this helps!

Andrew

AndersDK · Post by **AndersDK** » 15 May 2006, 23:56

Hi NiSk -

Here is the official situation schematic from Citroen PR-net :
XM series II
0271 03 395010 RIGIDITY REGULATOR SPHERE
http://www.citroen-pr.net/catalogues/il ... 950100.gif
Items 3 & 7 at rear.
Only the sphere spec differs according to Saloon/Estate/Engine type.
All other bits are the same.

Andrew's images are from an XM rear allright - but pre feb '93 - showing the early XM hydractive valve setup. This has the common rear/front electrovalve located separately elesewhere under the chassis body.
This situation is shown here :
0269 03 395010 SUSPENSION HYDRACTIVE JUSQU'A OPR 05928
http://www.citroen-pr.net/catalogues/il ... 950100.gif

Mandrake · Post by **Mandrake** » 16 May 2006, 00:03

Sorry,

I overlooked where you said it was an XM.

Regards,
Simon

NiSk · Post by **NiSk** » 16 May 2006, 07:01

Hi Simon & Anders,

Yes, I can see frommy own pdf of the spares list that Simon's is from a HA I, whereas The pic of the HA II is rather better than my own pdf. So it seems the electrovalve is when the rubber return pipe is connected, could this be so? The electrovalve certainly looks like it has a push-on hose connection.

The next problem is getting it out!

Does anyone know how it's held in place? and can it be removed in-situ or does the iron clump have to be removed first?

Well, I seem to be getting somewhere now - thanks to this great forum!

//NiSk

p.s just as a matter of curiosity, the Xantia hydractive control unit seems to be the same, but mounted upside down compared with the XM. Is it in fact the same component?

Post by **RichardW** » 16 May 2006, 08:45

NeilP had trouble with the rear hydractive unit on his Xantia a few months back - turned out it had split in 2! From the drawing Anders posted it looks like you will need to remove the block and bracket complete from underneath

Mandrake · Post by **Mandrake** » 16 May 2006, 09:02

NiSk wrote:Hi Simon & Anders,

Yes, I can see frommy own pdf of the spares list that Simon's is from a HA I, whereas The pic of the HA II is rather better than my own pdf.

Ok, now you have me confused....

I was talking about Hydractive 2 on a Xantia - Xantia's never came with Hydractive 1. Your 1998 XM should also be Hydractive 2. As Anders points out, early XM's (before 1993) used Hydractive 1, which has many differences.

So it seems the electrovalve is when the rubber return pipe is connected, could this be so? The electrovalve certainly looks like it has a push-on hose connection.

Got it in one...

the rubber return pipe is indeed connected to the electrovalve. Like any low pressure return pipe it can leak when the rubber gets old and hard and/or the clip loses its tension. I've already replaced mine with jubilee clips.

p.s just as a matter of curiosity, the Xantia hydractive control unit seems to be the same, but mounted upside down compared with the XM. Is it in fact the same component?

I believe so, although don't quote me on that.

Here's a pic of the front valve on my 1997 Xantia:

You can clearly see the rubber return line at the top with the jubilee clip on it.

Apparently the Mk2 Xantia's used a slightly redesigned Hydractive control block, I think deian has a picture of that later type on his flickr page, so perhaps he might link to it in this thread.

The next problem is getting it out!

Does anyone know how it's held in place? and can it be removed in-situ or does the iron clump have to be removed first?

If they're the same as the Xantia ones there are three long bolts through the housing holding the main unit to the chassis.

As well as that you have two normal pipe unions that must be uncoupled, an electrical plug, and the two large hydraulic pipes with the flared fittings - which can be a little bit challenging if spanner access is tight.

Tip: put a spanner on the large nut outside of the pipe to hold it still when you try to undo the small nut on the pipe, as if you're unlucky the outer nut might try to turn instead, which could damage the pipe. (One of mine was loose and tried to do this)

What you have is a large threaded bung which screws into the main housing (the large nut around the pipe at the top of my picture) which has an o-ring seal on it and holds the damper valve in place inside.

Into the hole in this fits the flared pipe fitting with a smaller nut to tighten it. You need to undo this middle nut without the outer one turning.

You can't/shouldn't bend the large hydraulic pipes any significant amount so to free them from the housing (they stick a long way inside) you need to disconnect everything else first, loosen the nuts holding the pipes, then remove the mounting bolts, and slide the whole unit one way then the other to free the pipes.

Regards,
Simon

NiSk · Post by **NiSk** » 16 May 2006, 10:11

Simon,

What an amazingly clean hydractive control unit! It looks like your going to a concors with it!

Thanks a lot for all the info - but I still cant see how the electrovalve is held in place in the hyractive block?

Slowly getting there!

//NiSk

Mandrake · Post by **Mandrake** » 16 May 2006, 11:27

NiSk wrote:Simon,

What an amazingly clean hydractive control unit! It looks like your going to a concors with it!

Nah, I think its just that we don't salt our roads over here.....

I did have it out looking for a problem and cleaned it in the process, but it wasn't that dirty to begin with...

Thanks a lot for all the info - but I still cant see how the electrovalve is held in place in the hyractive block?

Ah I see.

Perhaps the following pictures might help, which I just remembered bernie sent me a few weeks ago...(thanks again bernie)

Xantia Mk2 style Hydractive control block:

Electrovalve: (same for both versions)

Normally to remove it you disconnect the rubber hose (which you have to anyway to get the whole unit out) then undo the whole electrovalve by the black nut on the hose pipe fitting with a 16mm socket drive.

There is a nut at the base as well, but (a) its alloy, so easy to round the corners off, and (b) you can only get at it with a specially ground thin spanner anyway.

The electrovalve itself is held together with internal loctite, but here is what it looks like inside if you have the misfortune for it to come apart instead of seperate from the main block:

I would suggest not removing the electrovalve from the block unless you think its leaking at the base...(which seems unlikely to me)

Regards,
Simon

NiSk · Post by **NiSk** » 16 May 2006, 14:08

Excellent, Simon!

Just what I wanted! I have read on the major Swedish Citroën forum that the electrovalve corrodes at the face where it meets the iron casting. This appears to have happened to several owners of XM's and Xantias with HA II, So I'm guessing that its a fair chance that I have the same problem. I will naturally remove th eelectrovalve first, before I go buying anything, just to make shure that it really is just that.

I have also read on the same forum that disabling the hydractive system by removing the computer plug (or maybe just the fuse) blocks the electrovalve in teh closed position and stops just this type of leak. I will try that first and see if there is any difference.

The pic in the following link shows where the aluminium corrodes away and starts to leak:

http://forum.citroenakuten.com/viewtopi ... highlight=

Thanks a lot for all your help (and everyone elses!)

//NiSk

NiSk · Post by **NiSk** » 16 May 2006, 21:31

Well I've just confirmed that the fault is in the electrovalve, following a tip from the Swedish Citroën forum's Xantia side, I disconnected the hydractive system by pulling the plugs from the HA computer.

Result. No leak!

With the computer disabled the electrovalve is not enabled, the plunger is down and the LHM cannot get to the joint between the valve and the iron body.

So that's it - off to find a new or better used eletrovalve!

And a tip to anyone else with a leak from the middle of the rear axle - if it disappears when you unplug the HA computer - your electrovalve is leaking!

Mind you, the car is not very comfortable running in sport mode all the time! Better find a valve quick!

//NiSk

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