Anti-sink?

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Chrispy
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Post by Chrispy »

Right, I've been having a play. If you stop the car, and turn the engine off, the suspension does not drop (as far as we can tell) if you stay in the car. If you then get out, you can watch it drop about 3 inches at the back with like a hissing sound. If you adjust the lever in the car, the car does rise/ fall smoothly, but when the suspension is doing it's thing first thing on a morning when starting up, the front does go up in a series of jerks, then the back goes up quite smoothly. The lever insie the car is as stiff as hell so I'm tempted to lube that up this weekend.
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Post by Chrispy »

The front doesn't drop sharply but does rise in fits and starts, like in 2 jerks as it goes up. The rear seems to empty itself after you start it though and then takes a while to pump back up. I know this as if you set off straight away, the front still has damping, but the rear is as hard as rock. If you wait for it to fanny about pumping up it's fine. Weird....
Chrispy
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Post by Chrispy »

I think basically I need to know what is normal behaviour for these cars. Should they sink a little (a couple of inches) after you stop the engine and get out? Should the front suspension rise in jerks when you start the engine, followed by the rear suspension rising to level it off? Should the rear suspension be as hard as nails before it's had chance to rise and level off with the front? Should these cars take ages to perform the above? How often should the ticking be at various heights? Which is the return line for the LHM so I can test it?
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Post by RichardW »

"Should they sink a little (a couple of inches) after you stop the engine and get out? "
Yes, but only by the amount they went up by when you got out. Try it with the engine running to judge how much the correction should be.
"Should the front suspension rise in jerks when you start the engine,"
Not really, but it's not unusual for the rising to be in steps, due to the way the pressure equalises through the system. The rise on starting should only be small - equal to the amount the car went down when you got in.
" followed by the rear suspension rising to level it off? "
Not really, on my previous car both ends came up more or less together.
"Should the rear suspension be as hard as nails before it's had chance to rise and level off with the front? "
No, this means that your rear is dropping to the floor, and it's hard because you have no pressure there.
"Should these cars take ages to perform the above?"
They can be quite slow due to the low ouput of the split pump, however, if all is working A1, the light should go out in a few seconds, and you are then ready to drive off, as the suspension is already pumped up. Pumping up from flat takes ages.
" How often should the ticking be at various heights? "
More than every 30s at normal height. Should be longer at full or min height.
"Which is the return line for the LHM so I can test it?"
All but one of the rubber lines connected to the tank are returns. There should be a fat suction line to the pump, and then two largish returns from the pressure regulator and PAS, and the rest are the operational and leak off returns (mostly small).
First thing I would do is get the rear up on ramps, and drown the height corrector in Plus Gas, take off the plastic link and clean the balls (carefully) and refit with plenty of grease, then do a load of Citaerobics, then drown the H/C in your lubricant of choice (spray grease, chain lube etc) then do some more citaerobics. Then see where you're at.
BTW you say it's an LX, but does it have hydractive suspension (button next to the handbrake in front of the manual height adjuster)?
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Post by Chrispy »

Ahh....I see. No, the car is a bog standard 6 sphere jobby, not hydractive. As soon as I start the car, the light goes out so I think that's ok. At normal hgeight, the ticking is every 11 seconds, when at full height it's much less often. The car doesn't sink to the floor overnight, but it does sink a bit once you've gotten out. I think then, when you re-start the car it pumps up the front suspension, then the rear sinks a bit, then pumps up to match the front. The whole process takes about 15 seconds from start to finish every morning, so I sit patiently for it to do it before setting off as the rear has no damping till it's done. I have no puddles of LHM on the drive so I doubt it's an external leak. Also, when doing citerobics, the front and rears go up/ down separately. When going up or down, the front does it first, then the rear and it's a jerky movement at the front, not smooth. The rear is smooth however.
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Post by RichardW »

If the STOP light goes out immediately you start the engine and the tick is 11 seconds, the accumulator is flat. It does sound like the rear is 'over compensating' so I should think a good lube up of the rear height corrector is in order.
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Post by Chrispy »

I've just been out in it now to pick up some LHM. When you start it, the rear actually sinks then pumps back up, then sinks a tiny bit again (like 1/2 an inch). From what I've read, is this the accumulator sphere? That'll explain why the rear feels hard if you set off straight away as it's sinking before pumping back up.
It's done 65k and I belive the rear spheres, the anti sink sphere and the accumulator sphere are the original ones....
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Post by RichardW »

Anti sink might be flat too, but slap a new accumulator on and see what happens.
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Post by Chrispy »

Are they hard to do? It looks like a bit of a pig to get to right down the front of the block... Is cracking them difficult? The Haynes manual (crappy as ever) just says to use a strap tool like what you'd use on an oil filter...
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Post by Kowalski »

The accumulator sphere is easiest to do with a large chisel and a big hammer from the top, a lot of people don't like the hammer and chisel method but it is effective. Failing that, if you jack the car up and get the undertray off its accessable from underneath, access isn't good because of various pipes and so on, I couldn't really get in on either of mine with the tools I like to use, hence the hammer and chisel technique.
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Post by jeremy »

In the Citroen official manual for the BX they picture a large double chain wrench for removing the spheres. GSF sell one that apparently works well. I made one up out of the hexagonal bar that was the basis of a Draper chain wrench (with 1/2 in socket fitting) with a band of 1.5mm steel welded onto opposite flats so that it is self tightening. Not a thing of beauty but it takes me longer to fit than undo any sphere yet including rear ones which turned out to be about 10 years old.
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Post by FrenchLeave »

Sorry for the late entry after everyone else has done all the work. Just a few random thoughts:
1. Front suspension moving in jerks, sounds as if the rams are sticking. It may be worth while lubricating the front struts - there are recent posts explaining how to do this.
2. Rear suspension is rock hard if you drive off before the suspension has pumped up. The suspension works by using a column of fluid, supplied by the pump via the height corrector valves, to transfer the movement of the wheels to the springing medium - the gas in the spheres. If you don't allow time for the suspension to pump up there is no column of fluid and therefore no springing.
3. Because the rear suspension carries less weight, it requires less pressure to raise to its working height. You would therefore expect the rear to pump up before the front. The fact that your front comes up first, together with the fact that the rear sinks overnight despite having anti sink valves, suggests a large internal leak probably from one or both of the rear suspension cylinders. Best way to check is to follow the previous suggestion and look for excessive flow from the return lines at the reservoir. Of course, if your work on lubricating the height correctors is successful that doesn't apply.
4. One of the joys of owning a Citroen is that for every fault there are half a dozen possible answers!
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