Xantia with recurring ticks

bruno · Post by **bruno** » 07 Feb 2009, 15:28

Hello all!

First, let me say: I'm a long time lurker here. Read loads of stuff and learned a lot from all of you. I've always wanted to take part in the community but some registration problems prevented me from doing so.

I'm the proud owner of a late phase I Xantia with the 2.0 16v petrol engine. It's been mine for 2 years and it is my first hydropneumatic car. Here in Brazil Citroën has never been a popular brand, so I've managed to get this one in good condition and cheap. Since it is hard to find a mechanic who would venture to mess with it, I do most of the hidraulic maintenance myself. I've changed the main accumulator, twice the back spheres (the 2nd time I've fitted comfort spheres which are more suitable to our roads), the brake doseur and front suspension cilinder return hoses. I try to take good care of it since it's my daily car. There is no noticeable leaks, and the hoses and pipes seem in good order.

Now I have some symptoms of a minor problem which I still can't quite pinpoint. They may be connected, so here they go:

First, the easiest: there is a considerable flow from the upper return brake doseur hose (about 100 ml/min). Strangely the lower one is okay (no flux). I've managed to get another doseur from a 50 K km activa, which I haven't fitted yet, but now am worried that other part may be at fault. Is the upper return connected to the back suspension circuit? The flow is there no matter the position of the suspension.

Second, the frequent ticking. Strangely the tick pretty much disappears after I mess with the circuit, making me think it is all right. I've just returned from a mess around with the LHM filters and everything is good: ticks every minute, sit at the back with the engine stopped and it pulls me up (and back down after I take my weight out of it). The accumulator seems new. I've wondered if it isn't some internal moving part which became dirty (I've changed the LHM 3 months ago, but it is again dirty and dark). So again I'm looking at the doseur and heigh correctors? If it were the correctors, what other symptoms would occur?

Third, the groaning noise after I stop the car. Seems like pressure escaping from somewhere, but where? Again, there are no noticeable leaks, and I'd have thought that o-rings and other junctions would let LHM go if they where at fault. Also, it seems to happen only when I drive a long stretch, so the LHM is warm. If the doseur valve would lose pression fast, then the pressure waves would make some noise (although I'm not sure if it could be that high a frequency).

Fourth, the brake pedal pulsates (sometimes along with the rest of the car), if I drive sportly. After I turn the engine off it comes back to normal, and the car seems to brake well anyways.

Although there's these things, and the anti-sink sphere that I have to replace, I must say I'm very happy with the car. I've been bitten by the citro bug and would change it only to get a C5. Just hope I can sort these things soon -- hopefully by only fitting the new brake doseur that I've got!

Post by **myglaren** » 07 Feb 2009, 16:18

Welcome to the FCF Bruno.

Your mention of the LHM becoming discoloured so quickly would seem to me to be a significant factor, plus the constant return flow from the brake doseur.

I'd guess at seals being corroded*. Could the LHM have been contaminated - is it possible that standard brake fluid or ATF has been added to the reservoir?

If you can get hold of some, I'd suggest running it on Hydriricage for a few months then replacing the LHM again but while the LHM is drained, have a look at the doseur seals.

*not really the word I want - your English is better than mine

bruno · Post by **bruno** » 07 Feb 2009, 16:58

Hello myglaren! Thanks for answering.

Which seals are you referring to? Seems like an answer to the symptoms, and may it be cured by changing the doseur?

I've never put DOT brake fluid or ATF in the reservoir. Six months ago, though, the LHM was equally dirty, so I've put 1/2 litre of butyl diglycol (Shell's Butyl Dioxitol) in order to try and clean the system -- I took the suggestion form the clubxm forum. After running for a month with that I drained the old LHM and filled with new oil. Hydroaurincage can't be found around these parts, so we have to make do with some ingenuity.

Post by **myglaren** » 07 Feb 2009, 17:24

Considering the discolouration I would be suspecting all the seals if there has been any contamination of the LHM.

I have no knowledge whatsoever of the butyl diglycol you mention so couldn't offer an opinion on it or whether it has degraded your seals. Unlikely if the ClubXm recommend it, perhaps something a previous owner or workshop has done? Seems a bit unlikely too considering the time you have owned the car.

AndersDK · Post by **AndersDK** » 07 Feb 2009, 17:39

Hi Bruno -

The doseur (brake master) valve contains 2 working seals in its rear brakes circuit
Otherwise the doseaur valve relies completely on the micrometer precise machining of internal parts.

However it seems that in most cases it does make a miracle to dismantle the valve and clean it.
On reassembly it must be filled up with fresh LHM prior to fitting.

The 2 plastic/rubber pipes returning the fluid from the valve to the reservoir, are connected internally both in the doseur valve and at the reservoir.
They are the "working returns" from the doseur valve, and you should only have a short time flow here, once you RELEASE the brake pedal.
There are 2 pipes to cope with the release pressure

A constant flow in the return means the doseur valve itself is leaking.
Its not connected to thge rear brakes circuit, but the valve may still leak internally and cause a slow drain of the rear suspension circuit pressure.

If you decide to overhaul the doseur valve, you will need these seals :

79.03.065.984 (1ea.) O-RING 16,4X19-1,3 (tephlone ring)
95.495.759 (1ea.) DOSEUR SEAL 14,7X14,9-2 (rubber O-ring)
95.638.813 (1ea.) O-RING TOR 42 T1,6 (housing seal)
recommanded to replace as well :
95.640.067 PROTECTOR RUBBER - C001 (rubber knob)
5.424.455 (1ea.) DOSEUR RING 27X32-7 (ring for rubber knob)

Note the "weird" part nos. These parts are the same used in doseur valves ever since the first doseur valve used in late D models.
Hence the old style Citroen part nos.

Any second hand doseur valve from a hydraulic Citroen should fit your Xantia. There are only minor design changes over the models/years.

bruno · Post by **bruno** » 07 Feb 2009, 18:29

@myglaren: I have read a lot about seal compatibility, and butyl diglycol is safe. The only point which I'm uncertain is the sphere membranes themselves, but so far no screw-ups -- at least it is relatively easy to know whether the sphere membrane has given out.

@AndersDK. Thanks a bunch. Do you recommend I keep the "new" doseur drenched in LHM? It may be a week or so before I fit it.

I've found out that by pumping the brakes I can make the back suspension drop a bit. May be the drain of the rear circuit you're referring to.

Also, just two questions: if the rubber return pipes are connected internally, shouldn't they both share the return flux? Odd thing for me, that there's only one with a flow.

Another thing is that from your post it seems to me that I have to order those parts if I decide to overhaul the doseur I already have. The previous owner told me he has done that, because of the dreaded LHM in the carpet problem. Is it possible that the internal pistons with micrometer tolerances are leaking themselves? At any rate, should I change the seals and o-rings of the "new" doseur I've got? It's got everything, including the protector and the doseur ring.

Thanks a lot, people.

Post by **myglaren** » 07 Feb 2009, 18:39

It's the heavy contamination of the LHM that leads me to believe that something has attacked the seals, the disintegrating seals being responsible for the discoloration.

If this is the case then it is also possible that material from the seals is blocking the brake doseur ffffrom closing - but not all the time as you report that there is an intermittent component to this.

Can you try emptying the LHM reservoir and checking the fluid and filters for particles?

bruno · Post by **bruno** » 07 Feb 2009, 19:02

I took the filters out this morning. There were some dirt particles in the "waning moon"-shaped one, but it wasn't much given that it was six months since last I cleaned the filters. Most of the problem is the discoloration of the LHM, there isn't that many particles in suspension.

The LHM was dirty before I put the dioxitol in. Can it be just that the system wasn't properly cleaned? Of course I'd rather the seals were fine anyway, but also there's the fact that nothing is leaking out of the system. I'd imagine that if the seals where generally in a bad shape there would be a lot of leaks springing out of everywhere.

Post by **myglaren** » 07 Feb 2009, 20:10

bruno wrote:I took the filters out this morning. There were some dirt particles in the "waning moon"-shaped one, but it wasn't much given that it was six months since last I cleaned the filters. Most of the problem is the discoloration of the LHM, there isn't that many particles in suspension.

The LHM was dirty before I put the dioxitol in. Can it be just that the system wasn't properly cleaned?

Always a possibility

Of course I'd rather the seals were fine anyway, but also there's the fact that nothing is leaking out of the system. I'd imagine that if the seals where generally in a bad shape there would be a lot of leaks springing out of everywhere.

Also true. It could also be residual rubbish from the old spheres.

I would follow Anders advice to swap the dosseur and at the same time drain as much LHM as possible then refresh it.

AndersDK · Post by **AndersDK** » 07 Feb 2009, 22:14

If the doseur valve you have now has been overhauled - and still leaks badly in the return pipe - then its simply worn out.

If the LHM is dirty, or any other non-lubing stuff is put into the system, the precision parts wear and allow for leaks.

I recommand you find another doseur valve and dismantle it, to learn how it functions.
It is completely different from any other brake master cylinder you would find on a conventional car.

You dont need to drench the doseur valve in LHM. What I mean is the valve should be assembled wet with LHM and filled with LHM to vent out air.

You will find very good service info here :
http://www.rwbsmith.plus.com/citroen2/Brakes/doseur.pdf

The most important seals are no. 17 & 18 on page 3 in that document.
They are always the cause for rear brakes circuit leaks.