accumulator sphere ?, Noisy after m.o.t

[blue94auto]

Dear Xm Connoisseurs,
I am quite pleased that my car has just flew through its mot but what do they get up to while we take the dog for an hour walk?
I started the car after the mot and the accumulator sounds like a sewing machine,fast clicking,like it never has before.
I was dragging my heels with regards to replacing the accumulator sphere,I have just ordered a new one.
Could the mad clicking mean the sphere has gone completely flat or ruptured.
Only hope a fresh sphere calms thing down.
Gary

[noz]

Hi Gary,

Welcome back to the fold.

I think your analysis is spot on. The symptoms you describe are exactly what you would get with no pressure left in the accumulator.

However, just to be sure.... the clicking noise is definitely coming from the regulator and not the pump? The frequency of the clicks does not rise when you rev the engine?

Cheers

noz

[Peter.N.]

I would replace it as soon as possible if its any age, I have had high pressure pipe failure due to a flat accumulator not cushioning the pressure rise when the pump cuts in.

Peter

[blue94auto]

Thanks for the replies Noz and Peter,it's good to be back.
I just had a run down to St Helens to pick up a cement mixer from my bro in law,come in useful these hatch backs eh. about 30 miles in all on the m6 and m58.
As diesel has hit £1.40 per litre I stayed at 50 with the revs about 1800,the noise coming from the accumulator (I think) .........if you can imagine the usual hiss that we get from these xms ,well it now has a rhythm . The hissing noise is now interrupted by the very quick pulsating/clicking noise coming from the accumulator.
I tried listening to both the pump and the accumulator with a 20 inch tyre lever lol,with all the hissing and clicking it was hard to eliminate either.
When ones ear is held against the tyre lever of all things! it sounds like a low clucking noise,I will find screw driver with a big handle and try and diagnose it tomorrow.
I don't think the clucking rises with the revs I think it quite constant.
I will be happy when that new sphere comes.
Gary

[blue94auto]

Hello,still waiting on the new accumulator sphere, however driving home this morning I had the readout" Hydraulic pressure low" good job I fixed the digital display a couple of months back,also the "stop" warning lights up.
I have parked the car up until I put the new sphere on,(warning heeded Peter)I am taking it that the pressure warning will be a result of the sphere being duff.
I haven't had a chance to diagnose the source of the sound but pretty sure it's the accumulator.
Been busy paving the rear garden,Joy.
Gary
Ps what is the best way of removing the acc sphere,using a chain type oil filter wrench from above?

[Peter.N.]

Hi Garry

I don't think a duff accumulator will give you a low pressure warning, it could be due to low fluid level although I would have thought you would have checked, or aa air leak in the inlet hose to the pump, they are prone to cracking just above the pump, the other possibility is a slipping drive belt but only if its of the 'V' variety.

Peter

[dean]

Hi Gary

There is only really one thing it can be that gives rapid regulator cycling and now a low pressure warning, it would seem there is an internal leakage in the hydraulic ssystem.

check the return of the brake valve and if its a hydractive 2 check the electrovalve returns too, first though check there is plenty of fluid in the resovoir as that will bring the warning lights on.

D

[blue94auto]

hello all, just fitted the new sphere about half hour ago,the pssst noise is still too fast, like not even a second interval ? The low brake and low hydraulic pressure warning have ceased.I checked the belt and its spot on same as the Lhm level.haven't checked the electrovalve returns yet,wait till daylight for that.can't figure why them warnings came on ,but on the test run the didn't show up.
Gary

[blue94auto]

Hello all,
I have just yesterday got back from five days down at Ross-on-Wye ,dragged the caravan down there 160 miles. The car towed without a problem and otherwise drove without a problem other than the psst psst psst continual hissing that it has done since the mot (accumulator sphere renewed)
However the low hydraulic and brake pressure warnings show on start up just after she has risen,if I blip the throttle they disappear until next start up.
This morning I noticed that when I turned the engine off, a continued escape of air is heard from underneath the car. I put the front of the car on ramps and started it up,put the suspension on high and ran the engine for a few minutes, from the sphere on the rear of the front subframe I can hear air escaping! when the engine is running this is masked by the noise of the engine and general hissing psst psst at the acc sphere.however when I am near the front comfort sphere ? I can hear air escaping. I got my son to turn the engine off whilst I tried to observe below, it is from there that the air escapes when the engine is turned off. Like a definite hiss about 3 seconds long.
Any ideas people.
Gary

[Peter.N.]

Hi Gary

I don't think its air you can hear but fluid returning to the reservoir possibly from a height corrector.

The pressure light coming on briefly is nothing to worry about, possibly the pressure is slow coming up either due to and internal leak (hissing noise?) or a worn pump but if everything works OK forget it.

Peter

[blue94auto]

oh what a clown am I ,it sounds like air but these xms of our do run by hydraulics don't they duh!
Thanks for that Peter.
I still have it on the ramps,I will go and have another look/listen.
catch you later.Gary

[blue94auto]

Hello again.
I have had a good poke around under there and got my mechanics stethoscope on and tracked the rushing fluid noise to the unit that is combined with the comfort sphere,it has an electric connector on it and a flexible pipe coming out of the front end.
when I put the probe on the body of this unit I can hear a metallic valve closing quite rapidly and putting the probe to the flexible pipe I can hear the fluid rushing through.
There is no such noises at the front height corrector.
I took the cap off the fluid reservoir and I could see the fluid pulsing with the timing of the clicks.
I was surprised at how hot the lhm is to touch.
The fdv valve clicks regularly every 3 seconds.
How would one track a component that is leaking internally? pull the leak of pipe of that unit and let it drain into a bucket, if it floods out then you have found the leaking component?
or compare the leak off rate with bucket method on say rear suspension units and see if they differ?
Any help most appreciated.
Gary

This post has been edited by blue94auto on June 04, 2011 08:43 am

[Dieselman]

I suspect the FDV is leaking fluid back to the tank via the power steering relief valve. One of mine was doing exactly this recently an on stripping the FDV I found the relief valve spring has lost all it's pressure.

This post has been edited by Dieselman on June 04, 2011 10:04 am

[blue94auto]

Thanks for that Dieselman, how did you fix the problem, by replacing the weak spring?
Or did you change the FDV.
Gary

[simonxm21]

this is interesting as mine hisses/psshhh click alot, well seems too, and sinks at the back as soon as the engine is switched off (give or take a few seconds).