Pressure Relief Valve Seized ????

Gregg1100 · Post by **Gregg1100** » 23 Mar 2008, 15:10

Hi,
Started to do the first of 4 new spheres today. I started on the two fronts---let car sink, undid relief valve 1/2 a turn, put sphere tool on
, but when I had cracked tightness and started to unscrew sphere, a brown coloured liquid stated to pour out from around the threads. May have been that colour because it was under pressure. I gave the pressure relief valve a few knocks with a tube of metal I had handy, but no difference. I cleaned it all up, tightened the spheres and relief valve screw. The car pumped back up to ride height ok.
Any ideas, please
Greg

Post by **CitroJim** » 23 Mar 2008, 15:25

Hi Greg,

AS Tom Jones might say, it's not unusual. I very much doubt if the relief valve is at fault, especially if you heard a nice "rush" of LHM as you opened it.

What I suspect is that even though it was on low, there would still be residual pressure in the spheres and in opening the valve, the sudden release of pressure downwind of the anti-sink valve would have made it instantly shut, thereby trapping residual pressure in the sphere. Perhaps this is why it's better to open the valve with the engine still running.

It happens often on rear spheres. One of the fun aspects of anti-sink valves!

The other cause might have been that the sphere was totally flat and full of LHM.

If it was brown, the LHM is well due for a change...

Gregg1100 · Post by **Gregg1100** » 23 Mar 2008, 20:25

Hi Jim,
Thats just it---I never heard a thing. I know the front end was solid-no bounce at all--as you said, spheres must have been flat---service history says they were all changed in 2004, as was the LHM and filters.
I will keep the new balls till I can get LHM changed--no point in letting any crud into them. I will try undoing release screw on valve tomorrow with engine running.
Thanks,
Greg

weety · Post by **weety** » 23 Mar 2008, 21:06

manuals in the car (and its a tadge cold to be wandering around outside) but i seem to recall that the xants with anti sink sphere at the back have to be depressurised with the engine on and the steering turned from side to side.....

probably worth checking before you have another go at it....... mmmm just think of all that nice brown gunge in your rear height adjuster

thorter · Post by **thorter** » 23 Mar 2008, 21:17

You need to keep the engine running with the relief valve closed and the height lever at low until the last bit of pressure is released from the suspension.

When you undo the relief screw, as soon as the accumulator pressure becomes less than the suspension pressure, the anti sink valve closes and traps any remaining pressure.

Fred

Post by **CitroJim** » 23 Mar 2008, 21:37

weety wrote:just think of all that nice brown gunge in your rear height adjuster

A good 1000 miles of Hydraflush is well recommended...

Gregg1100 wrote:Thats just it---I never heard a thing.

This may point to your accumulator sphere being flat Greg. You should always hear a nice whilstling wooshing sound as pressure releases and LHM rushes back to the reservior. A sort of "psssssssssssssstttttwheeeeeee click" The click being the pressure regularor doing it's final tick on falling pressure.

What is your current regulator tick rate Greg?

Stempy · Post by **Stempy** » 23 Mar 2008, 23:27

Have you tried running the engine with the relief valve screw open? If it's jammed then the car will rise as normal, either that or the pressure will release the jammed valve, so if it does start to rise, stand well back.

Mandrake · Post by **Mandrake** » 24 Mar 2008, 06:41

thorter wrote:You need to keep the engine running with the relief valve closed and the height lever at low until the last bit of pressure is released from the suspension.

When you undo the relief screw, as soon as the accumulator pressure becomes less than the suspension pressure, the anti sink valve closes and traps any remaining pressure.

Fred

Got it in one Fred.

With anti-sink you MUST keep the pressure regulator bleed screw CLOSED and the engine IDLING until ALL pressure has been bled from the suspension - and that can take quite a while. On Hydractive models it can even take up to 3 minutes from the time you set the height lever to minimum, until there is no pressure in the suspension.

If I'm going to do a sphere change I usually set the lever to low and leave the engine idling (and bleed screw closed) while I go and get my overalls on.

I also check that I can wiggle the rear suspension spheres/cylinders to determine there is no pressure left in the rear, and because the rear takes longer to bleed, its usually a good sign that the front is probably bled too and that its ok to now shut the engine off and open the bleed screw and have a go at removing the spheres.

Regards,
Simon