Xantia drop links

kevin1962 · Post by **kevin1962** » 26 Apr 2006, 21:25

Can someone explain to me why a failing drop-link makes such a racket? I've visually checked them and I can't see any problems!

fastandfurryous · Post by **fastandfurryous** » 26 Apr 2006, 21:43

They can be about to fall off, and "visually" checking them will show nothing.

Once a ball joint wears, then there is play in it, and it will clunk on load reversal.

The issue with droplinks is that they see load reversal all the time while you drive down the road, so will clunk and clatter all the time. On poor road surfaces it can sound like a machine gun under the bonnet.

kevin1962 · Post by **kevin1962** » 26 Apr 2006, 21:49

Both drop links are really quite new (a few thousand miles). I've tugged on them with the wheels on the ground and not noticed any play. To check them properly should I have the wheels off the ground? Also, will oiling them help at all?

Post by **Peter.N.** » 26 Apr 2006, 22:15

I have just fitted a new n/s droplink to my XM because of the clatter, only to find that I had already replaced it and the original one appears to be perfect! So, I have something else that's making the same noise. It's obviously something else that experiences 'load reversal' inner arm bushes, anti roll bar bushes? I'm still looking

andmcit · Post by **andmcit** » 26 Apr 2006, 22:18

Oiling them wont to diddly!!

Tugging on the wheel doesn't have the same loading on the hub as the vehicles own weight on it's joints & bushes. In the past I said there's NO PLAY only to see a big bar levered onto the ground or against a fulcrum and actually HEARING & SEEING the movement...

It's worth checking the other obvious things too, such as the strut top donut rubbers, the wheel hub bearing, the bottom ball joint and the lower wishbone bushes...

Could all still boil down to cheap copied drop links though!

Andrew

kevin1962 · Post by **kevin1962** » 27 Apr 2006, 00:21

How much should genuine Citroen drop links cost? The ones I had fitted recently cost £23 inc VAT.

Mandrake · Post by **Mandrake** » 27 Apr 2006, 05:54

When I had a worn droplink (lower balljoint on the left side) I was able to feel the slack simply by grasping the link rod and yanking the rod left and right and feeling it click. (I'm not saying that you can always detect it this way however)

Unfortunately after replacing the droplink (the right hand side was ok) and checking both the bottom balljoints it still clatters over rough surfaces most of the time!

I hate to say this, (as I'm sure some people will think I'm just obsessed about this topic at the moment

) but I seriously believe that air in the suspension between the rams and the spheres causes almost identical symptoms to worn balljoints - eg noisy clatter and harshness over broken surfaces....(as well as poor ride in general)

If there is enough air getting in there (for example due a leaking pump or inlet hose - see my other threads) then you now no longer have a continuous column of incompressible oil (which is a linear device) connecting the hydraulic rams to the sphere diaphrams.

Instead you have these "gaps" which have a small bubble of compressible medium - air, which gives a non linear effect in the displacement vs force response of the suspension.

As soon as you hit a bump that is larger than the volume displacement of the air bubble the two columns of oil "slam" into each other violently and cause a jolt - just like a slack balljoint when the slack is taken up and the two metal surfaces hit each other. Oil in a hydraulic system is just as incompressible and rigid as a steel rod in this application.

I've checked my front suspension VERY thoroughly for slack and there is none. I've even replaced the strut cylinders for another reason so I know they're ok too. Balljoints ok, lower bushes ok. Still clatters over the bumps.

However, in the process of trying to track down a known air leak in the pump/hose, I have had a few occasions where the leak has temporarily stopped for long enough for me to thoroughly bleed the system (both the regulator, and the suspension using plenty of Citroerobics) and then go for a test drive over known and familiar stretches of road with *NO* clatter or harshness whatsoever. (Not to mention vastly improved ride and stability)

The ride returns to its clattery/harsh self again typically in about half an hour of driving. I can only assume this occurs due to fresh air being pumped back into the suspension during height corrections - a theory that is helped by the fact that the rear suspension seems to become harsh again before the front - and the rear makes a lot more height corrections while driving than the front, due to acceleration squat.

From this anecdotal evidence I think air bubbles could be the problem in many, but certainly not all cases where no mechanical problems can be found after repeated inspection and/or replacment of things like droplinks and balljoints...

I will let people know if I am able to fix the clattering problem permanently by fixing the air leak problem I have. (Which could be a job in itself if it turns out to be the pump, and not the hose!)

By the way Peter, mine seems to clatter more on the left hand side at the front too, and I have a theory for that as well. When oil is pumped into the suspension to lift it, it goes from the height corrector to the front hydractive block - and at the point where it goes in it has to split into two seperate flows - one to the left suspension strut and one to the right.

The interesting thing is that the pipe that goes to the left side exits from the TOP of the hydractive unit, while the right hand side exits the BOTTOM. If there were air bubbles being carried along in the oil flow it may be slightly more likely for the air to take the upwards direction at the T-junction rather than downwards, thus causing a disproportionate amount of the air to get lodged in the left hand side. (Just a theory

)

Regards,
Simon

mezuk04 · Post by **mezuk04** » 27 Apr 2006, 07:46

Not sure about the genuine Citroen ones?

But the ones at GSF are only about £14.50 + VAT...certainly were for the zx

Post by **Peter.N.** » 27 Apr 2006, 08:11

mandrake - Interesting theory, I will check it out. Just fitted a new pump!

Mandrake · Post by **Mandrake** » 27 Apr 2006, 09:36

Peter.N. wrote:mandrake - Interesting theory, I will check it out. Just fitted a new pump!

Hose not sealing properly then if its been disturbed perhaps ? Did the system get plenty of bleeding afterwards ?

Incidentally, what was the reason for replacing the pump ? I don't remember pumps needing replacing being a common problem on GS and CX's and yet I'm hearing about a lot of Xantia (and XM?) pumps being replaced, and I'm curious why...

Regards,
Smon

Post by **Peter.N.** » 27 Apr 2006, 10:23

Pump replaced because of slow pressure build up, particularly in cold weather, and it was noisey. Has improved things a bit but is still a bit on the slow side. Have replaced Accumulator sphere, pressure regulator and distribution reg, cleaned filters and changed fluid. Have I missed something? Hose seems OK no evidence of air in fluid.

Mandrake · Post by **Mandrake** » 27 Apr 2006, 10:51

Peter.N. wrote:Pump replaced because of slow pressure build up, particularly in cold weather, and it was noisey. Has improved things a bit but is still a bit on the slow side. Have replaced Accumulator sphere, pressure regulator and distribution reg, cleaned filters and changed fluid. Have I missed something? Hose seems OK no evidence of air in fluid.

How much slower than normal was the pressure build up ?

When my front electrovalve was leaking (and causing a 10 second regulator cycle time) it was taking about 15 seconds for the light to go out after starting from overnight. When I fixed that it dropped down to 8 seconds.

I hear a lot about 'weak pumps' but looking at how they work, I really can't see anything that would cause the pump to have a reduced pumping capacity, except for sucking in air of course, on the suction side of the pump.

The displacement of the pistons is a fixed quantity, it would require the non-return valves inside to leak for the pumping capacity to be reduced...(is that even possible, let alone likely ?)

As for the hose seeming ok, you won't be able to tell just from looking at it if it has hairline cracks. When you say no evidence of air in the fluid do you mean looking at how calm the surface of the oil in the tank is ?

Again, I've discovered thats not a very reliable indicator... yes - if there is a big leak, (for example the air that gets in when you disconnect and reconnect the hose) the surface of the oil inside the tank will froth like a beer, but if the leak is minor it wont.

Mine looks as calm as a millpond in the main tank area and yet my clear return hose I have connected says otherwise. (And for some reason my air leak is very intermitant as well)

Regards,
Simon

Post by **Peter.N.** » 27 Apr 2006, 14:59

Failure with pumps in the past has been because of the loss of one or more pistons output, maybe due to faulty valves, but I only seem to remember this on BXs and CXs.

The slow pressure rise only seemed to occur after those very cold cold nights we had this winter, it could take maybe a minute for the suspension to come up, and as we have to drive over a forest track to get to the road, the underneath took a bit of a battering! Even now, it can take 10-15 seconds for the light to go out although the suspension comes up quite quickly. The pump is cutting in every 20-30 seconds.

It definitly improved things when I replaced the pump, and it was much quieter , but I still dont think it is as quick as it ought to be.

rossnunn · Post by **rossnunn** » 27 Apr 2006, 20:39

guy lists droplinks on eBay, cheap. I'm not having alot of luck with him tho, responded to one mail then nothing no a sniff & I'm the one trying to give him some money!

kevin1962 · Post by **kevin1962** » 29 Apr 2006, 20:19

If the drop links are going to fail after such a short time is there, at least, a way of dampening the noise?