Folks,

I lost around 1 litre of LHM over the weekend from near the front of the sub
frame, close to where the six or so pipes (which travel down the nearside
from the front) disappear upwards over the tubular cross member.. Sure, oil
can travel in unusual directions, bit this is were is currently gathering
and dripping to the ground.

I seem to recall a recent posting about a leaking union somewhere in this
area. Can anyone recall this and advise?

I've had an initial poke around, and it seems that I will need to drop the
sub frame to even trace the leak (unless learned forum members know
otherwise!)

Does Haynes or Russek cover this in any detail? My mail concern with the
sub frame is damaging any pipes or wires. Sure, it needs to have its weight
taken by the jack, but I am aware that stuff may be connected to it that is
hidden above it.

I was due to replace the rear hydractive and anti-sink, so this is not too
much of a blow, but I'd rather have some idea of the scope of the work
before I start.

Thanks

Rob

'97 2.5 Estate

Hi Rob,

There are two possibilities:
1) One of the pipes passing above the tubular subframe is rusted through and leaking
2) The seals on the pistons inside the struts have gone and the breather pipe on the belows is passing oil into the inside of the tubular crossmember. From there it comes out the ends of the tube and appears just in front of the rear wheels.

If 1) then the job is made MUCH easier by dropping the subframe by a few inches. It can be done in place but will take you 10 times longer. I saw DJ do it on his 2 poster ramp. The ramp takes the weight of the car body with the wheels dangling down. The subframe is unbolted (just 4 bolts, remove 2 on the nearside and just slacken the 2 on the offside) and lowered down on a jack (or supported by a prop and the body lifted). You should consider doing the antisink sphere at the same time since access is a real problem unless you drop the subframe again.

If 2) then you have the same problem I have. The bores of the struts are badly worn in an oval shape and even new o-rings wont seal against the pistons. Subsequently the fluid bypasses the seals and ends up in the bellows and from there its pumped into the interior of the tubular crossmember. From there it pours out the ends of the tube.

Hope that helps. Please let me know if you need more detailed guidance once the source of the problem is known.

Cheers

noz

Super stuff, as usual, Norrie, thanks for your kind help!

DJ has replied in a similar vein on the XM-L forum.I take it that, once the pipes from the rest of the vehicle join the subframe, then they stay attached to it? In other words, I run no risk of damaging any pipes, apart from the area directly behind the n/s sill?

Do you have any tips on replacing the pipework? I'm looking at getting the various bits from Pleiades and grafting a bit in, should corrosion have made it neccessary.

As the leak does not seem to have great pressure behind it, and the brakes do not seem to have been affected, I'm assuming that its a return pipe. I take it that these are steel in this area?Fortunatly, I have the anti-sink and centre rear spheres in stock, and had intended to do these "sometime soon", so it's not too much of a blow.

Cheers

Rob

Hi Rob

Sorry, didn't see DJ's reply on XM-L.

Yes, there's plenty flexibility in the pipes. No chance of doing any damage. You only need to drop the subframe by a couple of inches to make the access much much easier. Its not like your taking it off completely or anything. However, there's a small risk that the disturbance will make another pipe (which was about to burst anyway)burst. You're as well knowing about all the weak pipes when you've got the subframe down anyway. Its not much more work. From memory, I think you'll need to remove the spare wheel carrier and possibly the rear exhaust box too for easy access to the pipes.

I'm not sure what kind of kit you have. Do you have a pipe flaring tool? Is it the vice mounted one or the spanner operated mobile one? Have you bought one yet?If it was me (and it happened to me too) I'd just replace the pipe which has burst along its complete length. For two reasons: 1. the replacement will be cupronickel and won't rust so future bursts won't be an issue and 2. It may be all together easier to access the pipe ends rather than try to splice a bit of new pipe in the middle. The vice mounted tool is fairly expensive whereas the mobile tool is a bit cheaper. You need to buy a minimum length of tubing in any case plus ends plus rubber seals. If you intend to splice you'll also need a few joining adaptors. All available from Pleiades. Thats where I buy all of my stuff. Alternatively, you could take the offending pipe off, measure it and let me know the length. I can make you up a pipe and post it to you. The car will be off the road for longer this way though. I have never priced them but apparently they're not too bad to buy from Citroen ready made up but don't quote me on that (on the basis it sounds highly unlikely).

Don't take the volume of escaping fluid as a guide to the source. The leaks, when they are caused by rust, start off as minute pinholes. Its immaterial anyway. The return pipes at that point are metal anyway rather than the plastic at other locations on the car.

Citroen only ever used steel. The mind boggles at the puny cost saving per car compared to cupronickel. The grief on the other hand when they get to this age is all to well known.

The Anti-Sink is mounted on a triangular bracket above the crossmember. The holding down bolts are almost impossible to get to with the crossmember in the normal position. Once its dropped, access is easy. The Hydractive sphere can be VERY tight. The last time we removed DJ's I used a pair of stilsons on the body of the electrovalve to hold it still whilst using a Pleiades tool to grip the sphere. It came off no problem after that. If you don't use the stilsons you can easily rip the electrovalve braket off the crossmember. Its made of very flimsy stuff. If that happens you can kiss goodbye to the large diameter hydractive pipes leading to the struts.

Hope that helps. Please let us know how you get on.

Cheers

noz

Cheers, Norrie,

I'll let you know, and may even take some photos.

Re the pinhole syndrome - this happened with a friend's BX - I went under to take a look at what I thought was a return pipe leak, and disturbed a still-pressured HP pipe.

My first lesson in the pressures the suspension runs at.

My first drenching in LHM.

I got out pretty quickly, and the "green mist" was truly something to behold as the pinhile aerosoled the LHM.

I need to take a look.

Thanks, once again, for the kind help and time to reply.

Cheers

rg

Folks,

A quick "high to low" resulted a flow of LHM like "grandma pouring gravy onto roast beef" on the way down, so I guess that it's the HC return.

This job is now set for post-Easter, a full couple of days, I guess. The anti sink and middle sphere will get done at the same time.

If I jack up the front to give access to the midships exhaust clamp (assuming I need to detach the middle box), are the front sills up to holding the weight? I've never been convinced about their strength as jacking points. Maybe I have bad memories of rotting HC Vivas.

Cheering news:- a quick go with the Pleiades tool with the suspension on high got the wheel spheres moving. I'd wire brushed and squirted them with penetrating fluid on each "sighting" for the last eighteen months, so maybe this has paid off...

rg

Hi Rob,

As a rule I never lift or support the car on the 'official' sill lifting points. Like you I have too many horrible memories. I also insist on being present when I have tyres fitted (the only reason I ever go near a garage) and insist that the flat chassis surface is used as the jacking point. It has always amazed me that if the Kik Fit bodger puts the jack up through your sill all you're ever going to get is a 'sorry mate' at best!

I'm not so sure the box needs removing all together, just lowered.

Cheers

noz

Cheers,

Yes, it seems totally unnatural to me. However, I have no choice at the (lighter) rear.

I popped into my local indie yesterday who says that possibile causes of pipe failure include "chafing". He claims that the plastic coating on the pipes is usually quite effective in the subframe area.

We shall see.

Cheers

rg

Folks,

I've dropped one side of the subframe, but really need to drop both sides to reach the suspect pipe.

How do I stop the HC linkage from the front of the car from being overstressed, whilst avoiding having the reset the ride height?

Pictures to follow. Eventually.

rg

Hi Rob,

When the height adjustment rod reaches the rear of the car there is a right angled bend in the last 20mm or so. The bend passes through a square hole in the mechanism which eventually connects to the height corrector. If I uderstand the bit you want to disconnect, just pull the rod and square hole to either side, in the opposite direction to one another, and they will come apart. You will not upset the height corrector setting by doing this because that setting is governed by the spring clamp fixed to the anti-roll bar. As long as the clamp is not moved then the height won't be altered either. The rod just sits on some light clips as it travels to the front of the car via the adjuster by the driver seat. Just dorp the rod out of the clips and let it dangle whilst you complete the job. The front height corrector works in the same way so you wont risk altering the front height either by doing this. I've attached the page from the manual which shows the linkage. Hopefully you can see the square-holed connector I described above.

I'm slightly surprised at having to drop the other (offsdie) side. From memory I thought you'd get enough room to work by removing the (2) bolts completely from the nearside and just slackening the (2) offside subframe bolts by 5-6 turns or so. Maybe my memory is not as good as it was.

Hope I've understood what you were saying. If not, just holler.

Cheers

noz

Cheers, Noz!

This is all bizarre, as I''ve been reading this stuff for the best part of three years, yet it's all very different when you "meet" the bits. I do recall the HC/roll bar relationship now.

The rear centre was a bit of a sod, as described on XM-L, but came off in the end...aaahhh...

Cheers

rg

One of the pipes from the HC back to the engine bay seems to have rotted through.

The scale of "wastage" is pretty scary. See

http://www.flickr.com/groups/xm_on_flickr/

More photos to follow.

The question is now whether I take the time out to splice in replacement sections for the other pipes that are "on the way"..

How resistant are HP pipes to surface corrosion?

And how long is a piece of string?

Thanks, once again, all for your kind help.

rg

Hi Rob,

The pipes are simply made from medium grade carbon steel. Some pipes are just bare steel, others have what looks like a black powder coated finish. I've never been able to work out why some are coated and others not. However, as soon as the black coating gets a small knick in it the water/salt mixture does its worst. The area above the rear circular crossmember seems prone probably because the water/salt sprayed up from the road gathers at that point. There won't be a lot of air circulation around there because its a bit out of the way so it stays damp most of the time. So you have an ideal breeding ground for rust.

Personally, when it happened to me I replaced a few of the worst looking pipes with the Cupronickel but then thats because I have the tool, ends and plenty pipe. If you were buying the individual lengths already made up you may come to a different viewpoint.

One tip - when you replace the sphere, clean up the mating surface with some emery or a wire brush and smear some copperslip on the surfaces before screwing the sphere into the base. Don't lubricate the threads though because the threads are on the clean, high pressure side of the seal. The rust only occurs at the pint where the two flat faces meet. I also add a smear of underseal around the joint all the way around after assembly. This prevents the water getting into the gap to do the damage in the first place. Remember also only to tighten the spheres hand tight. The tightness of the threads plays no part whatsoever in the sealing ability. Thats all carried out by the square section rubber o-ring.

Best of luck.

Cheers

noz

Noz.,

Thanks again.

More photos here, and more to follow.

http://www.flickr.com/groups/xm_on_flickr/pool/

The pipe is a return from the rear HC, and ends at a rubber hose near the front centre sphere. It's around 3450mm (!!) long. A ready-made one is coming from Pleiades, but I need to give thought to getting a tool. They are out of stock at the moment of the hand-held sort.

Phil. at Pleiades has been most helpful. I'd recommend them to all XM owners.

Pleiades@tesco.net

Cheers

rg

Thanks to all who helped with my 2.5's "major check", especially Noz.

It road-tested fine last night, and the back end felt much smoother, less choppy and jittery, though still "taut". I'd expect some improvement after four new spheres, though...

The heat shield is like tin foil thanks to corrosion. Are these a vital item, or can it be dispensed with? I guess that the diesel exhaust runs at much lower temperatures. The advantage, I guess, of keeping it is that it keeps dirt from the HC area.

So, after my anxious whittling of a few weeks back, I found that dropping the sub frame is not such a big deal, although I was scrabbling around for digital "before" photos of pipe runs at one point in order to work out routing.

Martin at Pleiades was most helpful. The cupro-nickel brake pipe is wonderful stuff. Martin said "you can almost tie your shoelaces with it", and he's quite right.

rg