Workaround for bubbles in LHM return flow

bernie · Unread post by **bernie** » 02 Aug 2007, 12:58

jorgy wrote:Hi all

someone here said that there's a bleeding nipple on the hydractive blocks of the HII cars. As much as I look on one, I can't see a bleeding nipple. Any ideas??

George

ps. looking at the document "RegulateurHydractive.pdf" at

http://fr.groups.yahoo.com/group/activa ... uspension/

Hi George
It's mine that has the bleed nipples on the HA blocks

jorgy · Unread post by **jorgy** » 02 Aug 2007, 13:17

Thanks Bernie, so

1/ I take it there is 1 per block?

2/ Can u help me understand its location? e.g. at the sphere side? opposite side? the sides where the suspension pipes come in? Near the e-valve? near the high-pressure pipe coming in?

3/ what sort of bolt/other fastener does it have? mms?

I'd like to bleed it as u did and see about bubbles.

thanks
George

Mandrake · Unread post by **Mandrake** » 02 Aug 2007, 20:48

jorgy wrote:Hi all

someone here said that there's a bleeding nipple on the hydractive blocks of the HII cars. As much as I look on one, I can't see a bleeding nipple. Any ideas??

Yep - only series 2 Xantia's have bleed nipples on the Hydractive Blocks - and possibly only the later series 2 like Bernie's. It seems they switched over to using XM Hydractive blocks after the XM finished, presumably to use up parts stock, and it is these blocks that have the bleed nipple, just like a brake bleed nipple.

Regards,
Simon

jorgy · Unread post by **jorgy** » 02 Aug 2007, 22:07

Hmmmm, then my XM doesn't seem to have it, it's an April 1994 HII. I wonder though which part of hte block this nipple intends to bleed?

G

Mandrake · Unread post by **Mandrake** » 03 Aug 2007, 00:09

jorgy wrote:Hmmmm, then my XM doesn't seem to have it, it's an April 1994 HII. I wonder though which part of hte block this nipple intends to bleed?

G

As I said, only the very late models of Xantia had that version of the block, quite likely only the late versions of the XM did as well.

The bleed nipple bleeds the main high pressure supply to the input of the electrovalve. Because the electrovalve only consumes a very tiny squirt of oil each time it switches on or off if there was air in the rather long pipe that feeds the electrovalve, it would probably take a few hundred on/off actions of the electrovalve to bleed the entire length of piping...(eg a few days of typical driving)

It's exactly like a brake caliper bleed nipple.

Regards,
Simon

jorgy · Unread post by **jorgy** » 03 Aug 2007, 00:30

Thanks !
G

pprado · Unread post by **pprado** » 08 Aug 2007, 04:01

Simon, I think I found a great tube to do bernie's V1/V2.

Got to a "house parts" store and talked to the seller who surprisingly suggested something cheap!

I went home with a flexible PVC hose that is used for connecting the faucet to the house's water circuit. Not only it does the curve nicely when tested, but also seems very easy to work with.

Investment was about $1.50

I just thought I would give this tip, maybe you can find one and try yourself...

See it here, named "Engate flexível de PVC":

http://www.tigre.com.br/content.aspx?rc ... &lnh_id=15

JohnCKL · Unread post by **JohnCKL** » 09 Aug 2007, 08:12

I think we should be careful what sort of piping we put into LHM which is an oil. It may break down or dissolve some rubber or perhaps even some plastic over time. I will try with a piece of rubber fuel tube which is fuel resistant and I hope oil resistant too. The rubber fuel tube is to be inserted inside the bottom return pipe which is 13mm and not outside it as the outside of the return pipe fit snugly into the filter. I'll try it out soon and see if it works.

pprado · Unread post by **pprado** » 09 Aug 2007, 13:06

JohnCKL wrote:I think we should be careful what sort of piping we put into LHM which is an oil. It may break down or dissolve some rubber or perhaps even some plastic over time. I will try with a piece of rubber fuel tube which is fuel resistant and I hope oil resistant too. The rubber fuel tube is to be inserted inside the bottom return pipe which is 13mm and not outside it as the outside of the return pipe fit snugly into the filter. I'll try it out soon and see if it works.

John, at least the rubber fuel hoses we have here have a fabric outside them.
Also... they used to kind of deteriorate :-O

Are you talking about the fuel pump-to-tank cover pipe? That seems to be really a good idea, I just don't know if that will fit...

Last thing... you will need something else to cover the pipe down because it has a fin, this needs to be covered or the bubbles will escape ayway

Ah, the pipe I described is made of PVC. But I'll put a part immersed on LHM and see how it does react...

Regards,

jorgy · Unread post by **jorgy** » 03 Sep 2007, 04:11

Hi all

Has anybody had any development with this issue? I haven't messed with the tank return, but:

On my side, I thought I should report that, being at 3,300kms on hydraflush, the last couple of weeks the suspension is becoming better and better, i.e., it is soft more often. When it is "good", it is still not able to absorb the most abrupt of unevenesses (it still makes the interior shake at some of them) but the difference is distinct in all types, it "rounds" them all more. E.g. it wallows more than before (almost 100% freely) at some wavy points on the itinerary I've been driving every day for the last year. And while before this "softness" was happening seemingly randomly and rarely, the last week it has been "good" for more than half of the days. The last 3 days I drove it, it has displayed only its "good" character.

In the past I had only been able to notice a relation between "good" behavior and hot weather -above 20C-. Now thought there is no such weather obviously. So, is the hydraflush doing something? Until last week, not seeing any difference, I had decided to put LHM back very soon and fit the 2 new front cylinders I have on the shelve, but now I'l lleave it in and see what happens till 5,000kms (the advised limit). I'm not sure whether this could be also related to a 700km trip I did up to Oban from Glasgow (70% twisty road) on the 20th of August: perhaps the liquid has flown more intensively in some low-flow bits, eg the hydractive block, or the suspension cylinders. Anyhow, we'll see. But I'm happier at the moment.

If it heals completely, this will prove it was 99% cylinder-stickiness related. E.g. I feel (and see on the mirror) these days clearly the rear "bottoming" quicker when starting from a traffic light. Not that before it didn't move in a similar way, it just takes less...milliseconds this to happen now, like it's freer, less damped. I leave the other 1% for the possibility that the hydractive piston-valves (I don't refer to the e-valves) in the hydractive blocks where actually sticking and not opening up fully the flow to the middle spheres, thus the car was actually in a semi-soft mode (despite all else being OK). I only give 1% to that because the car was actually very rough (something between road noise and very high-pitched vibration) also in broken tarmac of the kind that would require minimal wheel movement, thus fitting more to a really sticky strut effect.

Note that, after a year or so of observation, I can say it is *not* pressure-leak related. My cycling time has been 13-14secs steady since December 2006, LHM or hdyraflush, cold or hot, hard or "softer" days, no difference. The difference is clearly elsewhere. I ll keep you posted.

Also: somebody knowledgeable from the Planete-Citroen forum suggested it could be the anti-roll bars sticking. But somebody more knoweldgeable told me he couldn't see such a possibility (and I agree, cannot see how it could happen).

regards to all
George

pprado · Unread post by **pprado** » 03 Sep 2007, 05:00

I wish I had hydraflush here... Good to know that the clean is making difference

My sphere cycle time is short now, but I checked my front HA valve and it is leaky... a slow flow but it is. And the front is new... can't imagine how the back HA valve is leaking. Ride was good/random, but got worse since I cleaned my brake pressure sensor... I must have left some dirt, will check soon. I also need to put the HA mode LED.

Can't imagine the bushings from the anti-roll bar preventing the wheels to go up and down also!!!!

jorgy · Unread post by **jorgy** » 03 Sep 2007, 05:21

Hi Pedro

1/ hydraflush not available in Brazil? Surely you can buy somewhere online. Do you know the http://www.myparts.org/ website?

2/ you mean the front evalve was new and despite this it is now leaking?? That's unheard of!

3/ you know, all the difference between a 1 minute cylcing time and a 10secs one is only due to tiny leaks, a few mls in total. That's the ml range in the accumulator sphere between high-pressure (170bar) and low-pressure (145). I had calculated this difference to be about 17cc of volume in a standard 400cc accumulator. The system has to be in really perfect condition for the cycling time to be as designed to be!

Anyway, don't loose your courage, attack the problems one-by-one and you'll have an amazing ride at the end. I'm trying almost 3 years myself...

regards
G

Tof · Unread post by **Tof** » 30 Aug 2009, 17:36

Hi all!

I have similar problems to yours since I bought my lovely Xm. Two years of driving and a couple of times when I could feel a magic carpet ride. Two years of seeking what is wrong with the suspension, when everything looks good but harsh ride is still present...

I was very happy yesterday that I've found this forum. I've read whole the previous thread (14 pages) and I can see that many things that I tried to do, you did first. When I realized that all electronics and mechanics works as it should I came to air in LHM. It can't be anything else. Then your posts assure that.

I try to point out my experiences and thoughts:
- even 2000 Xm has no bleed screws in HA blocks
- my previous 1993 Xantia HA was very comfortable so age has no infuence
- my former 1996 Xantia noHA and three BXs had the same problem as present Xm. As I know many C5 drivers have it too, so the "air problem" is probably not only present in HA2 cars
- my pressure regulator clicks every 40-50s
- the most airated LHM I find after turn and hold steering wheel to lock
- everytime the suspension worked superb the steering was significantly lighter
- lately when I've replaced suction pipe and O-rings in pump (LHM had a day for de-airating) the car rose up quite quickly for the first time, then it was much slower (just like always)

The last post is two years old. Have you got any final solution? Have you found any air leaks in the return pipes? Any new ideas?...

pprado · Unread post by **pprado** » 30 Aug 2009, 19:39

I was thinking of this thread these days. Good that it was woken up.
My Xantia history was kinda frozen as I was directing all money to the new house and its (neverending...) list of things to buy.

However in the last months I've been working on it. I've replaced the 2 strut mounts (sphere support as citroen calls it), as one of them was in incredibly bad shape... I still can't believe my strut didn't pop up!

Anyway, being a noob at that job I spent a good amount of LHM and needed to top it again.
(Every time the strut came down as I was trying to make it through the mounting, it would spit LHM on me. How dare him?

)

I then needed to refill the tank. There I found the hack I created to "detour" the bubbles to the top of the tank which was just some piping (and needed to remove the filter).

I went ahead and cleaned the pump filter which was in bad shape, removed the hack and installed a bernie-registered version

of it with the return filter in place.

Well, again, the steering was so light I thought the wheels were on soap, even when idling. The ride was somewhat better but that can be because of the new strut mountings.
I still need to fix the lower arm bushings, which may be helping on the job of transferring potholes to my bones, some spheres and a good system clean.

What I recommend you to do is to use a section of transparent piping in the path to the pump, so you can see if your bubble problem is big or not.
I did that and then did the same on the return piping from the steering and that was the bubble feeder.
Putting the steering return pipe on the reservoir's top made the bubble flow decrease a LOT.

Regards,
Pedro Prado

bernie · Unread post by **bernie** » 30 Aug 2009, 19:44

pprado wrote: a bernie-registered version