Front drops with REALLY loud creaking

Chrispy · Post by **Chrispy** » 13 Jul 2005, 23:31

Hi all,
I've posted this question up before, but never really got a clear answer as it was mixed in with a load of other questions which got priority.
Anyway, on occasion after starting the car, the front end drops rather violently and creaks really really loud. This isn't just a mild groaning from the front struts, but a really loud creeeeeak from the middle of the car. It's almost like the front is too high when you start the car and it's dropping to normal height really fast because after it's done it, it doesn't re-rise.
The noise can be quite alarming and freaked my passenger out today as we left work, not to mention the drop at the same time.
Also, the back still drops after starting the car most times and then pumps itself back up then down a bit then back up.
I've changed the acc sphere for a known good one, now having 2 min ticking intervals compared to 5 second ones [8D], and doused the height correctors in WD40 and lithium grease.
Is there anything else I can look as because these 2 faults are really starting to annoy me now. [xx(]
Cheers,
Chris.

Stempy · Post by **Stempy** » 14 Jul 2005, 00:04

Have you done citaerobics? Give a good old session, five or six times from min to max. The creaking can actually be hydraulic fluid as it flows through the pipework. The back drop thing was cured on mine by replacing the anti sink sphere. A chenge of LHM can do wonders too.
I've found that a good thing to lube the linkages with is motorcycle chain lube as it's thin and penetrates as you spray it on then thickens up and protects and lubricates the linkage as the solvent evaporates and is designed to work in such harsh environments.

Chrispy · Post by **Chrispy** » 14 Jul 2005, 00:39

I've done a few citaerobics from min to max (including last night), but it still persists on doing it now and then. I've also greased the front struts but to no avail. So the anti sink sphere cured your rear sinking? Nice...I shall replace that baby next. The new acc sphere makes it pump up much faster but hasn't cured the drop on startup so let's hope the anti sink one does. As for the front horrendous noise, is that fluid rushing back through the system or is it the height corrector making the row?

Stempy · Post by **Stempy** » 14 Jul 2005, 03:45

Be careful when you replace the anti sink as it doesn't fit like the others. It has a pipe fitted to it behind the bracket that it is screwed to, if you just unscrew the sphere you will wreck the pipe, so make sure you undo the pipe first. IIRC you'll need an 11mm spanner. You'll also want a 4.5mm seal that fits between the pipe and the sphere, available from GSF but not Citroen!
The noise at the front could just as easily be caused by a problem at the rear, but it definately seems to be a sudden realease of hydraulic pressure. When you do citaerobics does the rear come up first, followed by the front?

Mandrake · Post by **Mandrake** » 14 Jul 2005, 09:01

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Chrispy

Hi all,
I've posted this question up before, but never really got a clear answer as it was mixed in with a load of other questions which got priority.
Anyway, on occasion after starting the car, the front end drops rather violently and creaks really really loud. This isn't just a mild groaning from the front struts, but a really loud creeeeeak from the middle of the car. It's almost like the front is too high when you start the car and it's dropping to normal height really fast because after it's done it, it doesn't re-rise.
<hr height="1" noshade id="quote"></blockquote id="quote">
I think I know the noise you're talking about it - I've heard it on a few rare occasions on my Dad's car, although that was back before we greased the struts. It's a very loud shuddering noise, more than just a normal strut creak.
I think its caused by the anti-sink valves chattering open and closed under abnormal or unusual circumstances. For example if you lift the car up to full height, then open the pressure regulator bleed screw, both anti-sink valves will immediately close.
If you then set the manual height lever back to normal or right down, the car will stay up due to the anti-sink valves, even though the height corrector is fully open in the down direction. If you then close the bleed screw again (with engine running) as soon as the pressure reaches the point where the anti-sink valves open again, the car will drop like a rock, and sometimes at this point you will get the very loud shuddering you're talking about, which as I say, I think is caused by the anti-sink valves chattering under extreme circumstances - the chattering of the valve directly translating to shuddering movement of the actual suspension, as the pressure is not released smoothly...
What could cause this to happen under normal circumstances I don't know. The only possible scenario I can think of is:
Car with quite a bit of extra weight/luggage etc pulls up, passengers get out and leave luggage in the car, car height adjusts back down to normal.
Some time later (half an hour ?) the anti-sink valves close due to pressure loss at the main accumulator, possibly hastened by people getting in and out of the car causing some corrections made using stored pressure.
Then after the anti-sink valves are closed someone removes the extra luggage from the car, and the height rises, but the height corrector despite being in the position to lower the car, can't because the anti-sink valves are closed, so the car remains at a height that is too high.
Some time later you start the engine, the pressure in the accumulator comes up, anti-sink valves close, *WHOOSH* height drops suddenly as the height corrector was already fully open, and the anti-sink valves may chatter, as they are not designed to open or close when the height corrector is fully open.
Just a long shot [;)]
Regards,
Simon

Post by **RichardW** » 14 Jul 2005, 12:58

I know the noise too... Apparently it is caused by the one of the hydraulic pipes vibrating against the bodywork somewhere if the suspension comes down when, as suggested, the anti-sink valve is only just open. Only used to happen on my previous (non HA) Xantia if I dropped the height from max after leaving it standing a while. Happens occasionally on my current (HA) one after starting, as it drops the rear on the floor shortly after stopping, leaving the front sticking up in the air. I think Citroen used to fit an insulating block if customers complained about it - if you try a search, you might turn up an (old!) post describing it. If you can stop the rear sinking, and the system loosing pressure, then the problem will (probably!) go away anyway!

Mandrake · Post by **Mandrake** » 14 Jul 2005, 18:04

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by RichardW

I know the noise too... Apparently it is caused by the one of the hydraulic pipes vibrating against the bodywork somewhere if the suspension comes down when, as suggested, the anti-sink valve is only just open. Only used to happen on my previous (non HA) Xantia if I dropped the height from max after leaving it standing a while. Happens occasionally on my current (HA) one after starting, as it drops the rear on the floor shortly after stopping, leaving the front sticking up in the air. I think Citroen used to fit an insulating block if customers complained about it - if you try a search, you might turn up an (old!) post describing it. If you can stop the rear sinking, and the system loosing pressure, then the problem will (probably!) go away anyway!
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The shudder is much too noisy and violent to be just a pipe vibrating somewhere, the shudder shakes the whole car and can be felt through the entire car when it happens. I still think its the anti-sink valve (one or both) chattering as they try to open under load with a height corrector that is itself already open. Maybe the anti-sink valve is unable to open quickly and cleanly when the pressure is trying to return back to the tank via the height corrector.
By causing the suspension pressure to drop in abrupt pulses, the shuddering is transmitted directly to the rams in the struts and thus felt by the passenger.
If it's the back anti-sink valve doing it, it could well happen more easily if the anti-sink sphere was dead. If that hasn't been replaced and since the back is droping suddenly when starting, that would be a good first port of call...
Regards,
Simon

Chrispy · Post by **Chrispy** » 14 Jul 2005, 18:24

Hmmm....interesting. Well, I'm in the process of ordering an anti-sink sphere now to fit on Saturday. What's this seal you mentioned? I might have to order that too if that's the case.... I take it the procedure is the same for changing the AS sphere? Drop the car all the way down, jack it up, axle stands, undo pipe on rear of sphere, unscrew sphere (using hammer and chisel as it's not going to be used again) and replace with new one. Then do citaerobics. Is bleeding the rear brakes a good idea at this stage as where would the excess air go from the inside of the sphere once fitted other than the brakes? Or does citaerobics do thi?
The noise when the front drops is a really loud chattering/ creaking noise. It does travel through the whole car and only happens when the front drops violently. When doing citaerobics, the rear rises first then the front. Same when starting the car as the rear drops, then rises, then the front HC corrects the front. Hopefully the new sphere will fix this though.

Chrispy · Post by **Chrispy** » 14 Jul 2005, 18:30

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Mandrake
What could cause this to happen under normal circumstances I don't know. The only possible scenario I can think of is:
Car with quite a bit of extra weight/luggage etc pulls up, passengers get out and leave luggage in the car, car height adjusts back down to normal.
Some time later (half an hour ?) the anti-sink valves close due to pressure loss at the main accumulator, possibly hastened by people getting in and out of the car causing some corrections made using stored pressure.
Then after the anti-sink valves are closed someone removes the extra luggage from the car, and the height rises, but the height corrector despite being in the position to lower the car, can't because the anti-sink valves are closed, so the car remains at a height that is too high.
Some time later you start the engine, the pressure in the accumulator comes up, anti-sink valves close, *WHOOSH* height drops suddenly as the height corrector was already fully open, and the anti-sink valves may chatter, as they are not designed to open or close when the height corrector is fully open.
Just a long shot [;)]
Regards,
Simon
<hr height="1" noshade id="quote"></blockquote id="quote">
Well, to answer that question, this does it when there's just me in the car, getting out, leaving it an hour or 2, getting back in, starting it and CREEEEEEAAAAK as the front end suddenly drops. It's almost like I've parked up, the front was way too high and I've turned the engine off and the front does not correct it's height. Then as soon as I restart the engine, the front end slams down a good few inches accompanied by the awful noise. Funny thing is, the usual issue of the rear sinking/ re-rising on startup doesn't occur when the front drops this way. It's either one or the other.
Something tells me the anti sink sphere will sort this as it will be able to retain some system pressure. Perhaps, as soon as the engine is started, the accumulator sphere is charged, causing the anti sink valves to open. Then, with the anti sink sphere being flat/ buggered, all the fluid runs in its direction effectivly robbing the rest of the system of LHM pressure, thus causing the sudden drop.
How does that theory sound?

Stempy · Post by **Stempy** » 14 Jul 2005, 23:40

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Chrispy

Hmmm....interesting. Well, I'm in the process of ordering an anti-sink sphere now to fit on Saturday. What's this seal you mentioned? I might have to order that too if that's the case.... I take it the procedure is the same for changing the AS sphere? Drop the car all the way down, jack it up, axle stands, undo pipe on rear of sphere, unscrew sphere (using hammer and chisel as it's not going to be used again) and replace with new one. Then do citaerobics. Is bleeding the rear brakes a good idea at this stage as where would the excess air go from the inside of the sphere once fitted other than the brakes? Or does citaerobics do thi?
The noise when the front drops is a really loud chattering/ creaking noise. It does travel through the whole car and only happens when the front drops violently. When doing citaerobics, the rear rises first then the front. Same when starting the car as the rear drops, then rises, then the front HC corrects the front. Hopefully the new sphere will fix this though.
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The seal is part number N65998 from GSF, the procedure is the same as other spheres not forgetting to release the valve on the regulator block. Citaerobics will bleed the suspension system but bleeding the brakes may be worthwhile anyway.

Mandrake · Post by **Mandrake** » 15 Jul 2005, 02:28

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Chrispy

Hmmm....interesting. Well, I'm in the process of ordering an anti-sink sphere now to fit on Saturday. What's this seal you mentioned? I might have to order that too if that's the case.... I take it the procedure is the same for changing the AS sphere?
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Yes, do all that, but you also must deplete any pressure in the anti-sink sphere, as it is basically a brake accumulator that only comes into play after the anti-sink valve closes. That means after depressirising everything else, you need to do about 30 or so hard applications of the brake pedal to use up any stored pressure there.... you should notice the brake pedal get soft after that. (Note: if the sphere is completely dead, it won't be storing any brake pressure, and the brake pedal will be soft immediately...)
Probably a good idea to check that a (jacked up) back wheel can be turned by hand with the brake pedal pressed to confirm there is no pressure waiting to surprise you when you undo the pipe [:D]
The seal is slipped over the pipe that is screwed directly into the end of the sphere. From accounts of other people it sounds like when you undo the pipe the seal tends to stay in the sphere and you'll need to fish it out with a piece of bent wire. This is probably how some people loose the seal. (Don't realise its still in the old sphere when they chuck it...) Of course if the person before you did that, the seal could be missing...
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
Drop the car all the way down, jack it up, axle stands, undo pipe on rear of sphere, unscrew sphere (using hammer and chisel as it's not going to be used again) and replace with new one. Then do citaerobics. Is bleeding the rear brakes a good idea at this stage as where would the excess air go from the inside of the sphere once fitted other than the brakes? Or does citaerobics do thi?
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I would bleed the back brakes as well to be sure...
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
The noise when the front drops is a really loud chattering/ creaking noise. It does travel through the whole car and only happens when the front drops violently. When doing citaerobics, the rear rises first then the front. Same when starting the car as the rear drops, then rises, then the front HC corrects the front. Hopefully the new sphere will fix this though.
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Yep, its definately the same noise I'm thinking of.... but other than causing it to happen by the deliberate procedure I mentioned, I'm still not sure what might trigger it in "normal" operation.... but we'll see whether this helps you first..
Regards,
Simon

Chrispy · Post by **Chrispy** » 16 Jul 2005, 20:52

Righto, in addition to changing my front drop link today (O/S) I changed my anti sink sphere. After lowering the car all the way and releasing the pressure from the acc sphere (which gave a lovely gurgly hiss this time unlike before I changed it) I made a start. First bother was getting the arse jacked up with the suspension set to low. There's not a lot of room under there for a jack! I ended up using my trolley jack under the rear towing eye on the N/S which got it high enough to put an axle stand under the read subframe mount. Also, my fecking Citroen jack folded up on me as I was trying to lift the sill with it and so went in the bin. Why they supply you with a jack not stong enough to lift the car is beyond me.....PSA muppets.
The nut attaching the sphere to the LHM pipe is a 9mm too(which I didn't have so a trip to Halfrauds was in order).
Anyway, whilst I was at Halfrauds getting my 9mm spanner etc for the sphere nut, I got a 1.5 ton Draper scissor jack (£15.99) which is really flat and fits perfectly under the sill with the car on the lowest setting! Nice....
T'was all fairly easy after that but still required a hammer and chisel to crack the sphere free from its mounting. My strap wrench once again failed me and just creaked and slipped.
New sphere on (hand tight), nut tightened up, and engine started. 9 bouts of Citerobics and all is well.
Hopefully this will stop the bloody thing from dropping like a stone after I start it. It seems to be behaving itself so far....

Post by **CitroJim** » 16 Jul 2005, 21:25

Good stuff Chrispy! That's two of us who have at a successful hydraulics day then...

Chrispy · Post by **Chrispy** » 16 Jul 2005, 22:03

You too? What you been up to then Jim?

Post by **CitroJim** » 17 Jul 2005, 00:37

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Chrispy

You too? What you been up to then Jim?
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Replacing my rusty strut tops... "Discovered" I have ABS too...