Stuck Valves?, They whine but they don't clunk

I've been thinking that my valves must be working all right because they emit a high pitched whine when doors are opened etc etc. The other day I was reading a thread - maybe from Peter N ?? - which said that there should be should be an audible clunk when they open and close.

Does the fact that mine don't clunk mean they are jammed? is there an electrical fix for this or is more likely to be mechanical/sludge related. My suspension is hard, for the record and am currently giving it a thorough going flush with Hydraurincage.

Jamie

The whine means the electrical side is working. However, that does not mean the hydraulic side is working.

Given that you have a hard ride and cannot hear any clunk then I would say your electrical side may be OK (as long as it switches OK in driving) but that the hydraulic side probably isn't. I suffer the same occasionally. I will then notice it suddenly rise/fall when it does open and the center sphere is at the wrong pressure.

The valves need a high enough hydraulic pressure to work correctly, and may be prone to sludge causing problems - not sure about that. Geroge has written quite a lot on here about how the pressure regulator can get lazy and give a lower pressure range than it should which causes the valves not to open correctly. This can be fixed but requires the ability to test the cut-in and cut-out pressure. I'm sure someone will be along shortly with more info on that.

This post has been edited by rowanmoor on September 09, 2008 02:10 pm

Thanks for the post. Yes - I've been following the pressure discussions. I'm keeping my fingers crossed that something dramatic will happen with the desludging effect of the hydraflush ... but I'm not holding my breath!


Jamie

Hi Jamie,

I think a few of us on here have similar problems to yourself. I am running on hydraflush as well and now have the scenario of the rear sometimes clunking and softening up and sometimes not. It never used to do this running on lhm so I can only assume there is a sludge problem but I am also starting to suspect pressure problems as well.

Sounds to me as though the diodes in the solonoids have gone o/c. What happens is that the valves open with the initial dc supply but witout the diodes the 1Khz pulse supply will not keep the valves open. If you hear a 'clonk' when the system is first energised but none when the 'whine' stops, that's what the problem will be.

Its not to difficult a job to do if you are handy with a soldering iron, the pads to solder the diodes to are allready in the ECU. If you dont fancy doing that, fit one of our friends black boxes from ebay, they just connect the diodes to the leads externally.

Peter.N.

i'll listen again but it's my belief that there;s no clunk at the beginning or end of the cycle. I'll test it by sticking my head close to them to see if they clunk in my ear. I'll also check out the box of tricks - can someone jog my memory as to what it's called or who makes them?

Thanks for the answers

Jamie

found it - roy.mackay@e-crofting.com

Jamie

Peter, will the solenoids continue to buzz if the diode problem is present. I had assumed they would stop buzzing - but hadn't really thought about it.

I would say the diode fix is a good precautionary move anyway even if the suspension is working fine at the moment. Given how cheep and/or easy it is.

Something else struck me.

While I might well have a pressure problem with the system due to sludge, that alone could could not be the reason why they don't work properly when the door is opened and the engine is off (ie the pump not working).

Jamie

Oh yes! The solonoids will still buzz but they are not being held open. I think the diodes possibly rectify any a/c content in the pulsed current giving additional holding current.

I have had this problem with two of mine, having already fitted the diodes to the green estate ECU, when I had the same problem on the black one I swapped the ECUs and it gave me an instant cure - so I did that one as well.

All now OK

Peter.

Hi Peter

Do you have pictures of the diodes? I´ll check them anyway, maybe my problem´s there

thanks
Caique

Hi Caique

You cannot access the diodes in the solonoids as they are integral with them, you can though fit them to the circuit board of the ECU, there are solder pads already there to take them.

If you look through previous posts you will find a picture of the board with the diodes fitted. Strangly, I have just done one today!

Peter.N.

Hi Caique
Suggest you read Roy Mackay's eBay listing for a simply fitted kit which fixes the defective diode problem http://cgi.ebay.co.uk/CITROEN-XM-SPHERES-H...id=p3911.c0.m14

Ken

Ken

sounds good, do you know him? know anyone who instlled? works?

caique

Hi Caique

Roy is a well known XM forum member and his diode kit is a popular solution (and also insurance against future diode failure). However bear in mind that the kit only fixes the diode problem and does not fix every suspension / hydraulic problem which can occur.

Roy also sells kits for economically repairing window regulators which replace the original corrosion prone mild steel wire (which snaps) with stainless steel wire.

Ken