LDS system bleeding/flushing

[508c5]

C5(x7) with hydro-pneumatic system which now unfortunately contains not only LDS but also engine oil (no) thanks to my dad

Is there a bleeding/flushing protocol available?

Is it available through Lexia?

Is there some appropriate flushing fluid i can also use?

Thank you

[Paul-R]

Has the vehicle been started since the engine oil was put in?

[508c5]

Has the vehicle been started since the engine oil was put in?

Yes, unfortunately

[Jay-Bruce]

Right, first off, don't panic, the engine oil into the LDS is not the absolute end of the world as LDS is pretty close to LHM in chemistry, and they are all hydrocarbon based oils. So I'm not worried about you incurring internal damage to seals / valves / internal corrosion of hydraulics components. But, back in the days of citroens having green blood (LHM hydraulic fluid) there was a special fluid for flushing the system, called hydraurincage / hydraflush, which was orange, no such product exists for LDS systems, and the design of the LDS tank is such that you cannot remove old fluid as easily, but it can be done, just a bit of a faff around.

To start with, you'd ideally want to depressurise the system, there are three ways of doing that, one is using the proper citroen / peugeot "lexia" interface on a laptop, the next is using a decent mid-tier professional laptop based diagnostics tool from delphi, "clones" of "lexia" and delphi diagnostics can be found on eBay and if you're feeling more adventurous AliExpress. The forum also has relationship with a dealer of diagnostics equipment who gives forum donors a discount on his already reasonably priced and quality lexia clones. The final way of depressurising the system is with the vehicle suitably supported you can open the brake bleed nipple looking screws on the two firmness regulators to "drain" the system pressure down. The rear firmness regulator is slap bang centre line between the spare wheel well and the cross-member of the rear subframe, the front one is inside the front right wheelarch, and you're going to be visiting that area anyways...

If you don't have access to the computer gadget-tronics to depressurise the system, don't worry, for a simple fluid change, simply put the vehicle to it's lowest height setting, and you'll get most of the fluid back to tank.

With the system depressurised / lowered as best as possible, next step is to drain the fluid from the LDS reservoir (tank). Remove the front right road wheel, remove the arch liner, and you'll find a rubber hose coming down from the LDS tank on the front right inner wing in the engine bay and running towards the steering pump, there's a join there, somewhere, split that, and drain the old fluid out.

If you have a decent fault code reader/diagnostic tool like the lexia / delphi I mentioned earlier, for bonus points you can lift the front left road wheel as well so the entire front end is lifted, and with battery disconnected, and ignition on, engine off, turn the steering lock to lock to get the old fluid out of the steering rack. If you don't have the fault code reader, don't do the battery off & steering lock to lock bit as you'll only make problems for yourself with fault codes and warning lights when the electronics get confused after you put the battery back on.

Now, start to put the car back together, rejoin the hoses, refit the archliners, the road wheels, tighten any bleed screws you opened on the firmness regulators etc, and put the car back on it's wheels. With the suspension at lowest setting, refill the suspension tank with LDS until you can just see it on the bottom of the basket. Start the engine, slowly turn lock to lock on the steering without stopping/holding at the ends of the lock, do this a couple of times and check the LDS level. Now raise the car up and down through it's full range of motion a couple of times, stopping at the lowest and topping up the LDS fluid as required. Repeat the steering lock to lock without stopping, check the fluid, repeat the up/down/repeat couple of times again checking for fluid being visible in the basket on the filler neck of the LDS tank each time the car is at lowest setting.

Finally, put the car to normal height setting and go for atest drive, fingers crossed you've got a nice floaty X7 with smooth power steering, if you don't have smooth steering and or floaty suspension, you just need to get the last of the air out by repeating the up down lock to lock rigmarole from the previous paragraph a few more times.

[Jay-Bruce]

Just had a horrible thought, everything I typed in the post above this was based on the engine oil that was poured into the LDS reservoir being clean new engine oil, if the engine oil that went into your LDS reservoir was clean and golden follow the procedure above and you'll also be golden. If the oil that went into the tank was black, disavow your current dad and adopt a new dad, and go through the similar procedure I wrote in this thread: viewtopic.php?t=73127

If it were dirty oil, you're basically going to have to flush the system lots of times until the fluid coming out is as translucent as the fluid you're pouring in. Carbon, which is the black stuff in used engine oil is hard as F**K and will wreck pumps/valves by effectively shotblasting their internals if dirty engine oil is allowed to run in the hydraulics system. The guy at moose pumps, who builds souped-up injector pumps for American diesel engines has basically said that any injector pump that sees waste mineral oil also known as "black diesel" is now as far as he is concerned scrap metal, he'll neither warranty his own pumps that have been subjected to black diesel, nor rebuild nor upgrade any customers pumps that have seen black diesel. https://www.oilburners.net/threads/moos ... res.57548/

[508c5]

Wow wow wowww...i guess you wrote the manuel (-: cudos

I have Lexia and the oil was fresh.

I hope to be the bearer of good news by next weekend

Thank you so much!

[GiveMeABreak]

I've already put the illustrated procedure here in the donating members section in case you need it.

Removing / Refitting the LDS Hydraulic Rerservoir

[508c5]

I've already put the illustrated procedure here in the donating members section in case you need it.

Removing / Refitting the LDS Hydraulic Rerservoir

[508c5]

What's the system's capacity? 3L ?

[GiveMeABreak]

The capacity of the system is 5.3 litres. But of course only refill to the marked lines as specified on the LOWEST suspension settings as per the procedure.

[508c5]

The capacity of the system is 5.3 litres. But of course only refill to the marked lines as specified on the LOWEST suspension settings as per the procedure.

Thx

[508c5]

I intend to do the work tomorrow... Is the inner "net" of the reservoir removable ? I want to extract some fluid before depressurizing because I assume much of it will spill out and i'd like to avoid it as much as possible...

[GiveMeABreak]

No, just uncouple the pipes under the LDS tank as per the procedure. The oil will gravity feed out there and you won't be wanting to reuse any of that in any case as it will be contaminated.

[Hell Razor5543]

I would (if you don't have a suitable drain tray) pick up a cheap washing up bowl to catch the LDS in. When I had to work on the hydraulics of my C5 last year having the bowl helped.

[508c5]

i have everything i need and i surely don't intend to reuse, however, since the system contains too much fluid now, i am sure it will be pouring out of the reservoir during the depressurizing procedure (which is the first action to take as i understand). i would like to avoid this .