Spheres, Hydraflush and Brake Bleeding

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CitroJim
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Re: Spheres, Hydraflush and Brake Bleeding

Post by CitroJim » 19 Oct 2016, 17:05

As James says...

And...
ihatecars wrote:hmmm.. maybe I think too much (or worry too much) but...
When you open it you'll hear a rushing sound as the system depressurises and LHM rushes back to the reservoir.
doesn't that mean the suspension will drop to low position?
No, because you are already on low if you followed the instructions ;)

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xantia_v6
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Re: Spheres, Hydraflush and Brake Bleeding

Post by xantia_v6 » 19 Oct 2016, 17:28

CitroJim wrote:As James says...

And...
ihatecars wrote:hmmm.. maybe I think too much (or worry too much) but...
When you open it you'll hear a rushing sound as the system depressurises and LHM rushes back to the reservoir.
doesn't that mean the suspension will drop to low position?
No, because you are already on low if you followed the instructions ;)
And if the car has anti- sink, the anti sink valves would close when the pressure release valve is opened , keeping the suspension pressurised, which is why you need to lower it first.

ksanturion10
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Re: Spheres, Hydraflush and Brake Bleeding

Post by ksanturion10 » 09 Nov 2018, 21:59

Hi there all,
I have many of the issues described into this forum and I'm very thankful that it exist with its solutions.
Because I'm about to change some spheres (accumulator first for sure, because the stearing and the breaks became bad), I woul like to ask two questions for a beginning(probably already answered somewhere):
1. I've read from xaynes and here that the depressurising 12 mm head bolt should be left open until all work is done over the hydraulic system. Is there any benefit, in terms of less LHM spillage, if I close it back after the system is depressurised and the engine is off? Also it seems there are two ways of depressurising, one with the engine running (here mentioned) and after the engine is off (haynes); is there any differences how is done?
2. When fitting the new spheres, should they be pressurized before or after mounting, or just fitting them how they are is enough?

Hell Razor5543
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Re: Spheres, Hydraflush and Brake Bleeding

Post by Hell Razor5543 » 09 Nov 2018, 22:19

When I had a Xantia, I would bottom her out (with the engine off), turn that bolt by one turn only (if you remove the bolt a small sealing bearing will come out, and almost certainly get lost), and wait for a minute or so (you may hear a faint whistling) before doing any work on the hydraulics. Once I had completed the work (and everything was back together and tight) I would run the engine for a minute or two before tightening the bolt, to allow fluid to move around (and help to vent any air back to the reservoir).

You cannot pressurise the spheres; this is done when they are on the car and an active part of the hydraulics. Make sure the square section sealing rings are properly fitted before doing the spheres up tightly (I failed to do this once, and the accumulator sphere seal split). The anti sink sphere at the back uses a tube seal (as it has a pipe screwed into it), but it is a good idea to also fit a square section seal, so that the sphere does not end up sticking to its' mounting bracket. Only do the spheres up hand tight (that is all they need), and, to make life easier in the future, loosen them off slightly and then take them back to hand tight every six months or so. Spheres that have been allowed to get tight over several years can require extreme measures to free them off (a hammer and chisel might well be required; I KNOW I have had to do this!!!).

One possible pitfall is that (in order to eliminate any air in their circuit) you will need to bleed the brakes. It is not uncommon for the bleed nipples to get rusty, and (if you are very unlucky) to shear when you try to undo them. The best way I have found (and been told) is to spray the bleed nipples with a releasing fluid daily for a week prior to the work taking place. This should save you from a potential problem I have found "Plus Gas" to be very good, but I do not know if you can get it in Bulgaria.

Before you start make sure the LHM reservoir has sufficient fluid, and you have another litre available, just in case. Once you have the system pressurised you will need to bleed the brakes. As they are dead ends for the fluid any air caught there cannot get out. It is possible to do it by yourself, but you need the engine running to keep the pressure up. You also need to make sure the brake pedal is pressed (I used a toolbox on the pedal to hold it down). Then remove each wheel in turn (working your way from back to front) and bleed the brakes until there are no bubbles in the fluid.

ksanturion10
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Re: Spheres, Hydraflush and Brake Bleeding

Post by ksanturion10 » 09 Nov 2018, 23:03

Thanks for the answer Hell Razor.
Generally this is how the latest problem arised. The car was administratively stopped from moving for 1 month :D, and I forgot her at normal level and I think it has anti-sink valve, because it sank very little from the normal position. Before this "problem", the LHM was between the marks at max height, but now the indicator goes down when I switch to max level. I have a minor (bigger now) leak from the pump, but I have the O-rings already for replacement thanks to the information from the forum. I think the accum sphere had ruptured because the thick time was bad already, when I took it. Also it seems, that during its stay the car developed a leak from the steering rack, but it may be also an engine oil dripping from the head covers, not sure (I've put some silicon there). Because I'm about to change also the groomets, then I will know for sure.
Till now I had replaced both front and rear disks and break pads, and the nipples are already sprayed with antirust spray, so when the time comes for bleading out, I think they will unscrew without a problem.
OK, just to see if I understood correctly from your feedback: the spheres should be pressurized (with nitrogen) after the mounting, I mean this is imperative or? -> will the new spheres take a little trip to the place for pressurizing or the car should not be driven, before they are pressurized with nitrogen?
About the sufficient LHM fluid into the reservoir, because as I mentioned above I'm short with it, shoul I top up before I start the removal of the spheres or the top up should be made last, just before turning the egine on with the 12 mm head screw closed?

Hell Razor5543
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Re: Spheres, Hydraflush and Brake Bleeding

Post by Hell Razor5543 » 09 Nov 2018, 23:16

If you are buying new spheres they will already have nitrogen in the gas chamber (please accept my apologies for any confusion; I though you meant pressurising the hydraulic system). You must make sure to get the correct spheres for your car, as there are differing pressure levels depending on what spheres are required. A basic late model will have six spheres (and the car will not be able to switch between sports/comfort mode), a high spec Xantia (with sports/comfort modes) will have eight spheres (and the ones for the 'corners' (wheels) will have different pressures than the 'corner' spheres for the basic Xantia), while the top range Activa has ten spheres. The spheres for the front suspension have a higher gas pressure than the ones for the rear suspension.

I would definitely make sure before starting work on the car the LHM level is properly between the two rings (with the suspension at its highest level), otherwise it is possible that, when you are bleeding the system, air will be drawn in through the reservoir as the LHM levels have dropped below the pickup nozzle.

How many miles has the car done? Citroen recommend changing the LHM every 36,000 miles or so, and the third change is preceded by a hydraflush, to clean out any dirt in the system (so at the 108,000 mile change). Hydraflush is, loosely speaking, a weak form of LHM with cleaning agents, and should only be used for a few thousand miles before being completely replaced by a full LHM top up (as it does not have the same level of lubrication the LHM has, so moving parts could seize, if the hydraflush is left in too long).

ksanturion10
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Re: Spheres, Hydraflush and Brake Bleeding

Post by ksanturion10 » 09 Nov 2018, 23:43

Thanks once more for the feedback and the hints.
Don't need to apologise, my writing is sometimes doubious and wrong in English terms :D.
I will try to check the markings of the spheres before ordering them, but as I'm aware, there are only 6. I will try to pick the correct ones.
As you are suggesting, I will first top up to the correct level, before the removal of the spheres.
I'm out for now, all the best.

P.S.: The car is rather old, I guess over 200K km for sure. The LHM, that was leaking from the pump before (the O-rings fitted perfect), was clean and green. I've ordered some new LHM, but with this amount of loss and after the final bleeding I think only to stabilize the level and leave it as it is. The current spheres have the citroen marking on them and they are fitted with regasing valves (rusted already), so for sure I will change them all. The oil filter also had the citroen/PSA marking (had big troubles removing it), but I don't believe that it wasn't changed since the car was produced :shock: 8-[