Xantia rear high pressure plumbing query...

[djadams]

Afternoon all, the next challenge in fixing my increasingly ungrateful Activa is that where the rear ram hose had rubbed itself to oblivion on a rigid high pressure line, that line appears to also have suffered... The rigid pipe in question goes to one leg of one of the K-shaped unions (of which only three legs are populated) very close to the offside brake pipe coil, where the activa ram hoses go up through the rear subframe and goes up through the same hole as the ram hose - the damaged bit is circled in the image below:

...and from a different angle showing it next to the ram hose, without the rag...

I can't quite tell what it connects to, and hence whether replacement requires me to drop the subframe, or whether the other end is actually also accessible and a replacement could be routed (maybe differently...) to whatever it needs to go to. One of the other two pipes from that K-union goes to (what I assume I'm correctly identifying as) the anti-sink sphere, and the other to the K-union to the side of the anti-sink sphere... The leaking pipe is spraying onto the new spiral-wrapped activa ram hose also marked below:

Does anyone know what the other end of the leaking rigid pipe connects to?

[wurlycorner]

That same pipe went on one of my Activa’s.
It was a number of years ago though and unfortunately I can’t remember where it went, but I can say that I remember I managed to replace it with difficulty, but without dropping the subframe (I’ve never done that on one - other than on the Activa I broke, where I dropped out the subframes and hydaulic system in one and then got the metal merchants to lift the stripped shell off for scrapping with their FLT, leaving me with the full running gear left on the trailer).

[XantiaNonStarter]

I think that pipe runs the length of the car and ultimately ends up at the brake doseur valve in the engine bay.

[wurlycorner]

Can’t find a full Activa hydraulic system diagram but found the one below for Xantia hydractive, linked out of this thread

[Stickyfinger]

Dropping the rear subframe is not hard and gives very good access.....see my blog
viewtopic.php?p=743545&hilit=Xantia+rea ... od#p743545

[wurlycorner]

Sticky to the rescue

[djadams]

Many thanks all - in between life continuing to get in the way I've been going through your replies and trying to compare them in my head to what I remember from under my car... Thanks very much for your help, all of you.

With your assistance I think I've got it sussed, I just don't like the answer

The first clue was that in the top of Sticky's two images the connections to the K-unions shown look like they might be a mirror image of my car - perhaps an LHD diagram / RHD car difference for some reason. Seems odd as obviously most of the rest of the components are in the same places so the lines from them to other components are longer on my car than they are in the diagram.

The diagram rear right K-union "17" has connections that from memory look like those to the rear left K-union on my car: anti sink valve, height corrector and other-K "16".
The diagram rear left "16" K-union shows two lines that look like the two I could trace from my rear right K, with one to the anti-sink sphere and one to the "17" K, but the third connection to "16" (which would then be the one I'm trying to trace) is not shown...

I have a nasty feeling that XantiaNonStarter is absolutely right, because a connection missing from that diagram (probably because it's a suspension diagram, not a brakes one) is the one feeding pressure from the rear suspension / anti-sink sphere to the brake valve!

I'm encouraged by Wurly remembering replacing it without dropping the subframe, but if it comes to it, Sticky's method for dropping the frame looks genius. Any idea what the thread size on the subframe bolts is? I think I probably have some M10x1.5 studding kicking about somewhere.

Annoyingly the car is nice and high on stands at the rear but on the deck on the bump stops at the front, so to replace a front to rear line I'll have to juggle the front up too - never fun on slightly sloping driveway. Any tips on how awkward to get to the brake valve is? I've never noticed it so I suspect it's quite buried, but I've never gone looking for it either... I'm assuming both ends of that line will be Citroen flares with rubber seals rather than DIN brake flares...

No doubt I'll be back in a few months to thank you all again and let you know how I got on

[Stickyfinger]

M12 rod, I only use one nut and a pair of vice grips..... I also release the pipes from the clips in the first section of the under car pipe carrier/cover to allow a longer "drop" without straining them

Treat the diagrams like a London Tube map = layout not measurements

I would consider one of the bespoke Citroen "pipe joiner" rather than replace a front-2-back pipe tbh.
https://www.facebook.com/profile.php?id=61551886559922

Brake pipes

[djadams]

That's a good shout, I'll look into just replacing the damaged section and leaving the rest undisturbed. Not sure where that brake distribution/junction block "17" is, but if that's on the bulkhead under the LHM reservoir then that'd be a right royal pain to get to!

Right - next step lower the rear subframe on studs and find a good location on that pipe to make a repair, measure it and buy the right sized repair connector and pipe... I'm guessing it's going to be a 3.5mm diameter pipe, but I'll measure it carefully before I order anything. I've not ordered anything from Der Franzose since before brexit(!) but I remember they had a great range of pipe and suitable compression fittings.

[Stickyfinger]

Correct, the multi junction (17 above) is under the LHM tank.....but is quite accessible once the tank is out...........

Is it pipe 10 or 14 that needs replacing ?

[djadams]

I believe the one that's gone is pipe 10 - shown in that diagram as going from the height corrector to the multi-junction block to provide rear suspension pressure reference for the brake valve...

[Stickyfinger]

Then I would consider a full pipe for that one.....the run is clean and the up-turn is not bad to thread up to the multi-connector.............it does not long to take the LHM tank out and as said the access to the multi connector is not bad.

[djadams]

Hoping to get the chance to have a bash at it this weekend - I'll get both ends up in the air and I've got everything I need to make up a full length pipe if I can get to the front end well enough... Wish me luck!

[Stickyfinger]

HAVE IT !....Good Luck