Workaround for bubbles in LHM return flow

[pprado]

a bernie-registered version

I am referring to your section of pipe that fits in the return filter rather than removing the return filter altogether

[Tof]

A propos - Bernie, could you post again the pictures of your V2 solution? Or something new if it exists . Those pics was removed and I can't see them

Pedro Prado - by now I observe LHM with torch through the filler hole but the first thing now I want to do is set some transparent pipe in suction hose and to replace two O-rings in power steering circuit (it exists only with 2.9 engine - this is four-way union with pressure sensor and return pipe). I have tiny leakage there. Maybe there is main problem

[bernie]

a bernie-registered version

I am referring to your section of pipe that fits in the return filter rather than removing the return filter altogether

Yes I knew it was the pipe mod, I was just surprised I was famous

Tof, I'll see if I still have the photo

[DickieG]

I now own Bernie's Xantia estate with the pipe mod (its still fitted to the car) but to be honest I can't say that it makes any noticeable difference to the hydraulic system by comparison to the other Xantia's I have which are as standard. Air or more specifically Nitrogen will inevitably enter the system by way of osmosis as it escapes through sphere membranes, especially when there are eight of them!

Bernie are you about to cross the Channel?

[pprado]

I now own Bernie's Xantia estate with the pipe mod (its still fitted to the car) but to be honest I can't say that it makes any noticeable difference to the hydraulic system by comparison to the other Xantia's I have which are as standard. Air or more specifically Nitrogen will inevitably enter the system by way of osmosis as it escapes through sphere membranes, especially when there are eight of them!

That's true, but the system is open on the reservoir so all nitrogen that escapes goes to the atmosphere. The problem I am chasing with the pipe hack is "bubble realimentation" - air gets in the system somewhere, and when it returns to the reservoir it gets sucked again from the pump. As more air gets into the system, more and more % of the system gets air instead of LHM.
The hack prevents the bubbles (actually most of the power steering's return flow) to be directly sucked by the pump. Bubbles go up with the LHM, and they disappear on the LHM surface.
At least, that's the goal

My next step is probably removing the security valve to see if it is sticky, and if it leaks to (and more problematic, FROM) the return piping.

[Tof]

Unfortunately, new orings in power steering circuit didn't help

New, transparent tube mounted just before LHM pump shows me how much of air is flowing to the system... I think that if the problem is in return hoses, it has to be in the main ones. I want to solve the problem by sealing up returns rather than separate suction and return in reservoir. As I've seen on www.service.citroen.com there is one return connecting pressure regulator and power steering and it costs ~100€ but firstly I want to be sure if it really needs to be replaced.

Scheme of return hoses in Xm II will be very helpful. Do you have some?

[Wesa]

I faced on this problem after cold weather -30C here in Finland. Steering came very sticky and stop light took more and more time to dim out. Suspension was also very hard. The fault was found from that 2 inch rubber pipe on pump line in the top of the tank. Small crack below, no oil leak but air leak inside. Replacing this gave floaty wheeling back, even better than ever during 10 years with 2 XM. Before I'we done my lessons with diodes, leds fitted, solenoid springs tuned and spheres filled etc. but all of time I had a feeling that sometimes it work well and sometimes not.

After pipe repair I still had "hard times" but less than ever. No visible foam/air in the reservoir. I read through this thread and started to think that one possible to air pass the system, the pump sealing. I know some of you guys were even replaced the pump without final solution. But because when I found the cracked hose, I felt quite heavy vacuum peaks by finger from this crack and thought if the whole suction hose assembly has too much resistance? It has two tight 90 deg corner piece, tiny hole (compared to CX hose) and hard plastic pipe in the middle section which is not equalize at all the pressure peaks and may suck air throught the seal, even little from new one?

I replaced the whole pipe assy by flexible fuel hose and find soon that floaty situation is much more constant. It's great still after 5 days without citrobics. Less rolling in corners, quite comfortable also in firm mode (leds).
Even better than any of my owned 6 Cx! (exluding bigger bumps due to shorter wheel movement!)

[xantos]

Good to have this thread back and running. Just speed-read the whole thing, again for the 10th time in my career as a Xantia owner

@bernie: Could you upload your pictures of V2 mod done on your LHM tank on a previous Xantia?

Just thinking of replacing every return pipe with transparent ones which would make diagnostics of air bubbles quick and easy. Are silicone based pipes LHM resistant?

I will also try to sink the inlet pipe (from LHM reservoir to pump) directly into the reservoir and cut the bottom of LHM cover (where the pipes are attached) so the bubbles dispersed on the surface to see if the ride improves. On my Xantia non-hydractive the ride is not so good as you would expect (but still better than a Clio )

[Wesa]

I believe this is not only problem in Hydractive systems, they are just more eager to misbehave due it? I remember that xantia and Cx get worse on long run and citrobics helped. What else it could be than air?

[Hell Razor5543]

I wonder if it might be worth making a plastic baffle to fit between the intake and output pipes, so that it would reduce the possibility of air being picked up?

[myglaren]

I wonder if it might be worth making a plastic baffle to fit between the intake and output pipes, so that it would reduce the possibility of air being picked up?

Have you seen this thread?

[Hell Razor5543]

I had indeed, but I am loathe to change things in such a way as to not be able to reverse said change, hence why I wondered if it were possible to make a simple baffle, and clip it into place.

[xantos]

I was thinking of a simple thing to avoid air bubbles... Just stuck the suction pipe directly into the reservoir! So you rule out fittings and "the mysterious o-ring" (that may be leaking and sucking in air) . Of course some modification must be made regarding the filter on the suction side (flip it 180° ). Just observed my LHM reservoir today with engine on. More bubbles in than in a cola

Probably will find time to do the mod tomorrow as well as the "10min mode".

[lcwin]

Bubbles in tank is 90% due to air leak at the INLET pipe to pump. If you remove the hose at the Tank side you will notice at the end of pipe there is a rised edge on one side only . After the first removal of the rubber pipe to pump you will damage the internal smooth rubber wall. This will give you the " bubble effect ".
Remedy - file down the lip on the tank pipe but don't remove all. Change or cut off 1/2 in of the existing inlet pipe. Clamp used must not don't kinked or distort the rubber pipe.
Another thing to look out for is heavy steering . This is due to excessive vacuum pressure on the inlet or air bubble. Clean the intake filter if needed.
Try this rather than doing modifications that may not work or worsen your problem. It works for me!

[white exec]

If you remove the hose at the Tank side you will notice at the end of pipe there is a rised edge on one side only.

Interesting. Could you post a photo?

Also important to use a hose clip here that does not distort the pipe, or clamp it unevenly. For this reason, thick/heavy jubilee clips are not suitable, which often fail to adopt a circular shape on small diameters. Thin-band (stainless) variety are better, as they form a better circle. The OE (factory) clips are good in this respect, but are usually discarded when pipework is removed.