Spheres, Hydraflush and Brake Bleeding

k2col · Unread post by **k2col** » 11 Dec 2008, 11:36

I'm not entirely sure where to find the "12mm bleed valve on the pressure regulator", could someone explain exactly how to find it pls?

Thanks

addo · Unread post by **addo** » 11 Dec 2008, 12:11

On the regulator, look for a 12mm bolt head towards the upper front that's not quite sitting flush on the casting, nor can be reasonably ascribed to any holding-down application. There's a rubber hose that often obscures it to newcomers.

Unread post by **CitroJim** » 11 Dec 2008, 12:32

The 12mm Bleed Valve will be found on the front of the Accumulator sphere block. It'll look like a bolt head slightly spaced off the surfce of the block. It's also the only 12mm bolt head on the block.

Only undo it by about half a turn, until you hear a the sound of LHM rushing back to the reservior. Leave a 12mm spanner on the slam panel to remind you to do it up again at the end of your work.

k2col · Unread post by **k2col** » 11 Dec 2008, 13:56

thanks for the quick responses guys - found it. Front sphere's changed, massive improvement in ride quality... no more bouncy bouncy!

MikeT · Unread post by **MikeT** » 22 Dec 2008, 11:53

I need to flush out the old LHM, having changed it for Hydraflush so thought I'd do a bit of research first. I notice the Haynes manual says to do them in order (of furthest first?) of OSR, NSR, OSF then NSF which isn't mentioned in this thread?

Does the suspension have to be at a particular setting and do I need to depressurise it first? I ask because whenever I jack up the car to use my axle stands, setting the suspension to LOW leaves the struts fully extended if that wheel is off the ground. Is that a problem?

Unread post by **CitroJim** » 23 Dec 2008, 10:44

It's pretty irrelevant really Mike. The Hydraflush will do it's magic over a few thousand miles and as long as you bleed about half a pint out of each rear nipple and a smaller amount out of each front, the majority of the old LHM will be out.

I always bleed on high with weight on the rear wheels so that there's plenty of pressure available in the rear braking circuits.

What is vitally important is you give the LHM reservior a thorough clean-out with petrol and you similarly give the filters a really good clean with petrol.

When you come to replace the hydraflush with LHM, bleed until nice green LHM comes through and job done

Unread post by **admiral51** » 23 Dec 2008, 11:22

Hi Mike
i did a hydraflush change and brake bleed last weekend and i always do the bleeding with the suspension on high and bleed them is this order n/s/f o/s/f n/s/r o/s/r. i tend to bleed about 250ml from the front and about 500ml from the back (think thats what a coke bottle holds

) and i do it as if i was just changing a wheel that way you always get pressure on the front/rear brake system

Hope this helps and not confuses the issue

Colin

floyd · Unread post by **floyd** » 02 Feb 2009, 19:16

Hi All,

Great info here, but need to identify one of the spheres on my 2.0 HDi xantia.

See link below to photo, which is the grey sphere to the right and does anyone know which i need to order from GSF.

http://www.flickr.com/photos/35073472@N08/

Thanks

http://www.flickr.com/photos/35073472@N08/

red_dwarfers · Unread post by **red_dwarfers** » 02 Feb 2009, 19:35

floyd wrote:Hi All,

Great info here, but need to identify one of the spheres on my 2.0 HDi xantia.

See link below to photo, which is the grey sphere to the right and does anyone know which i need to order from GSF.

http://www.flickr.com/photos/35073472@N08/

Thanks

http://www.flickr.com/photos/35073472@N08/

Didn't some of the very late Xantias come with C5 spheres fitted?

addo · Unread post by **addo** » 02 Feb 2009, 19:54

They had grey "slimline" spheres as an option on accumulator and rear centre (Hydractive) - lesser volume than a regular accumulator though.

floyd · Unread post by **floyd** » 02 Feb 2009, 19:57

This sphere appears to be leaking and needs replacing, do i use a C5 rear regulator?

Unread post by **CitroJim** » 02 Feb 2009, 20:49

floyd wrote:This sphere appears to be leaking and needs replacing, do i use a C5 rear regulator?

That's your rear Hydractive Centre Sphere Floyd. I doubt very much if the sphere itself is leaking; it's more likely the hydractive electrovalve body. Have a look at my V6 Blog and you'll see I have the same problem on my V6. You'll need to give the block a very good clean-up to seethe source of the leak.

If the leak stops when you pull the Hydractive ECU fuse (F8 Engine Bay)out, thus forcing the suspension to hard mode, that's the clincher. Remove and replace the fuse only with the ignition off.

Else that, the valve is faulty and it may be leaking excessively up the leakage return pipe (the black rubber pipe on the top of the valve) sometimes the leak can be so bad as to force the leakage return pipe off the valve spigot.

Those grey mushroom spheres have a very long life as the diaphragm does not flex so much as in the conventional green spheres. You may find the greay sphere has a different thread and is attached to the hydractive block by means of an adaptor. Remove the adaptor and you can fit a conventional green sphere if necessary.

As I say, the liklihood of the sphere leaking or being duff is very low.

floyd · Unread post by **floyd** » 03 Feb 2009, 09:45

Thanks jim will take a look at this and see what can do.

StevieM · Unread post by **StevieM** » 08 Mar 2009, 13:56

Quick question about changing rear centre sphere…..Xantia ’95 16v:-
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I have just got myself prepared to change the rear centre....have my sphere,9mm flare spanner (£5 from Halfords.....seems good quality), 4.5mm seal, penetrating oil, made a wrench from 1" square section 4' steel tube/6mm studding trick ("P" shape clamp)
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Question:-
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If I raise the car to highest point, to aid sticking trolley jack underneath/put axle stands under sills at regular jack point (don’t have any ramps!).....will the hydraulics de-pressurise sufficiently by subsequently putting on lowest setting/releasing 12mm bolt , despite rear of car being in the air (ie….weight off rear wheels)?????
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Pls advise, as I want to avoid LHM bath.
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Many Tks, Steve

Unread post by **CitroJim** » 08 Mar 2009, 14:11

Hi Steve,

Welcome to the forum

Yes, that'll depressurise sufficiently, no worries at all. If you want to be sure, just operate the foot brake a few times to exhaust the last few bars of pressure remaining in the circuit.

All jobs involving sphere changes are messy, however careful you are and it's hard to avoid a douche vert at times

LHM is pretty harmless stuff and as I've found on several occasions, it acts as a very good hair conditioner

Envirmonmentally too it seems OK; LHM soon disappears when spilt on concrete...