C5 Suspension

Toby_HDi · Post by **Toby_HDi** » 02 Oct 2010, 23:08

My brother has spotted a 2001 C5 for sale with the back end sat on the floor.

Never having looked at a C5 I'm not familiar with the system other than what would be common with the Xantia. From various threads I've seen on here I would be thinking suspension pump, I gather this is electric on the C5 rather than hydraulic?

Could this be the cause or is it likely to be something else? If it is the pump, what specifically is likely to be the fault and how would it be rectified? It is a 2.2 HDi.

As an aside, this C5 has 470k on the clock!

He has also just bought a 2002 406 HDi 110 estate with 313k! Who says these HDis don't do huge mileages

Citroenmad · Post by **Citroenmad** » 02 Oct 2010, 23:14

Is it estate or a saloon Toby?

Estates can be set down at the rear only, so it might be a fault with that. C5s do have height correctors as the Xantias, but have less pipework to them, though they still require lubricating.

It will be very obvious if the pump has stopped working, the front wont lift and if driven it will settle down to low after a while. The pump is electric and used ones can be sourced for a reasonable ammount.

Make sure it has LDS as they dont go well with LHM, which can cause problems with the pump and burn it out.

C5s suspension rarely causes any problems, though after that mileage i guess it will have hard work and hopefully spheres!

Its good going, 470K, i guess its only a few pennies to buy?

The 2.2 isnt quite as hardy as the 2.0 and it will have a FAP filter, so make sure thats not causing problems. I guess it will have had injectors by now, but check the engine for undue noise and that its not down on power.

Toby_HDi · Post by **Toby_HDi** » 02 Oct 2010, 23:15

Thanks Chris.

Yes, my apologies I forgot to mention, it's an estate.

Citroenmad · Post by **Citroenmad** » 02 Oct 2010, 23:20

Then there is a possibility that its something to do with the estates rear suspension. There is a button in the boot of the estates which allows the rear to be raised or lowered independant to the front. However its probably something to do with the height corrector, probably stiff.

First thing to do is check the pump is working, if it is and its lifting the front as it should - it should be very quick to raise the car, then look at the rear height corrector.

Post by **myglaren** » 02 Oct 2010, 23:30

As Chris mentions there is a manual height setting for the rear only.
There is a switch on the right hand side of the tailgate 'doorframe' that allows the tail to be raised or lowered.

It should be overridden on closure of the tailgate or engine start.
Could be a fault with the circuitry.

The pump should activate when the car is unlocked.

cachaciero · Post by **cachaciero** » 03 Oct 2010, 08:13

Possible causes of rear (or front) suspension dropping independently.

1. Blown seals in the strut, one would expect a certain amount of oil around the offending area for this fault.

2. Height corrector shot / badly adjusted.

3. Failed valve /valves in the Pump unit, assuming the pump can be heard to run.

4. If Estate stuck switch in boot (unheard off), system will work as normal with switch disconnected, or even connected if engine running (switch bypassed).

5. If H3+ center regulator stuck in hard mode, won't cause it to drop but will prevent it from rising again once strut pressure has been lost due to leakage.

The basic H3 system is mechanically simpler than the old LHM systems but more complicated electrically and more expensive at a component level.

Pump electronics coded to car, if the old ECU is good can be swapped into a pump unit from a "scrapper" if the only problem is the pump itself or the raise / lower valves.

As ever a Lexia is pretty well essential for accurate diagnosis and calibration of ride heights.

cachaciero

cachaciero · Post by **cachaciero** » 03 Oct 2010, 08:26

Citroenmad wrote:
Make sure it has LDS as they dont go well with LHM, which can cause problems with the pump and burn it out.

With respect I believe that that is "folklore" having researched the differences between LHM and LDS the only major difference is that one LDS is a semi synthetic base and the other LHM is a mineral base.
I would have no problem in topping up with LHM if no LDS was available, true there is some initial foaming when the two are initially mixed but this soon disappears after which the two remain completely mixed with no separating out. Whatever differences there are in terms of hydraulic wear / varnishing etc there is no reason why running on LHM would cause the motor to burn out.

cachaciero

addo · Post by **addo** » 03 Oct 2010, 10:13

One of the club fellows here, has a clear glass bottle with 50/50 mix of the two inside. There's no visible separation, and it has sat on his shelf almost a year.

Post by **myglaren** » 03 Oct 2010, 10:46

Which make me wonder what it was in Chris' LDS tank to cause it to froth and leak and generally misbehave.

Antifreeze perhaps

addo · Post by **addo** » 03 Oct 2010, 10:57

Maybe someone confused LDS and LHS, adding a product like RR363?

cachaciero · Post by **cachaciero** » 03 Oct 2010, 11:38

addo wrote:One of the club fellows here, has a clear glass bottle with 50/50 mix of the two inside. There's no visible separation, and it has sat on his shelf almost a year.

Know that experiment well, with similar results

cachaciero

cachaciero · Post by **cachaciero** » 03 Oct 2010, 11:52

myglaren wrote:Which make me wonder what it was in Chris' LDS tank to cause it to froth and leak and generally misbehave.

Antifreeze perhaps

I don't know I had read of Chris's experience before I started my limited experiments and research. One thing I did notice was that on initial mixing when shaken the mix would appear to froth, my first though was that this was a chemical reaction, however it only happens when agitated so my belief is that while mixing for some reason the mixture holds air for longer than it does when thoroughly mixed. I did notice that pure LDS also seems to froth more when agitated than does LHM. The mix I have in the garage seems "quite normal" in this respect after one year.

I could believe that if LHM was added to a tank of LDS there would be a degree of frothing for a while until well mixed but I am extremely skeptical that the ensuing mix would cause the pump to burn out or indeed any other serious problem in the short to medium term. Longer term maybe, LHM does over a period produce sludge which LDS may not. On an LHM car this is not a problem because the sludge gets trapped in the filters as it does in the LDS system the difference is that you can change the filters on an LHM system.

cachaciero

Post by **myglaren** » 03 Oct 2010, 12:10

It appears to be a very perverse logic that fits filters to trap particles and sludge but then doesn't allow them to be cleaned or changed.

cachaciero · Post by **cachaciero** » 03 Oct 2010, 12:32

myglaren wrote:It appears to be a very perverse logic that fits filters to trap particles and sludge but then doesn't allow them to be cleaned or changed.

The same logic that is applied to the 4HP20 box i.e no oil change required, is good for life is also applied to the C5 hydraulics.

LDS is very clean to start with when the car is new it is filled up under almost surgical conditions the amount of wear particles over five years will be relatively small and not enough to get anywhere near choking the filters so why would anybody want to change the filters, after all according to the plan the car will be thrown away by year six.

Citroenmad · Post by **Citroenmad** » 03 Oct 2010, 21:21

Well im not sure i agree with you. I had owned my car for a few months before it started causing problems - i had not topped up the suspension tank with anything. So the mixture was already in when i bought it, i had not opened the suspension resivoire.

I had a phonecall one day while i was at uni from my dad saying i should check my car as there is drops of white mayo like stuff where i had reversed out of the drive. I did check the car over but found nothing, i was in the C5 SX. I got home to check the other 2 cars which had been moved that day and nothing, mine however was sat in a large puddle of white gunk. As you can imagine at first i couldnt think what this would be caused by.

So i had a good inspection and found a leak at a joint in a rubber front suspension pipe, the pipe was still intact and i couldnt see why it would be leaking. I removed the pipe to put a jubilee clip on, i then took the cap off the LDS tank to check the level. Then when i tried to put the car into high the suspension pump was very noisey and the car wouldnt lift. I put in some more LDS and it slowly, very slowly, raised up to high, it took a good while.

So i was still not sure what the white foam was and the pump was not working. So i dropped it off the next day at the citroen indy who said it had LHM in the system, it was easy to smell it had, though i didnt think to smell it myself.

So the garage flushed out the system and put in fresh LDS. Its been fine ever since and not another leak. I do think the reaction of LHM and LDS in the system caused the foaming to create a leak, as i wouldnt have expected the very tight joint to leak.

The indy told me it was the 4th or 5th C5 they have had in which has been in with suspension problems resulting from LHM being added and not LDS. They said one of those needed a new pump as it was driven and driven the pump had gone. With my pump running so quickly but not having hardly any effect on the cars height its easy to see how the pump could burn out.

Id not even try putting in LHM even as a last measure. LDS is easy to get hold of and should be the only fluid added to a C5