LHM change- what a difference

[AndersDK]

1) Start engine, put suspension to lowest, open 12mm pressure screw about 1/2 a turn (you’ll hear a 'whoosh' noise), wait one minute, then stop engine

Unfortunately this will not work for any anti-sink model - as soon as you open the pressure release screw the anti-sink valves both close and the suspension won't go down any further.

Might I suggest:

1) Start the engine, pressure release screw closed, put the suspension on low, wait 2-3 minutes, stop the engine, open the pressure release screw.

Thats the recommended way to depressurize an anti-sink model. The 2-3 minutes is because even though the suspension stops visibly falling after about 30 seconds, oil continues to flow back to the tank for at least 2 minutes, and you don't want some flowing back AFTER you've disconnected the tank

Regards,
Simon

Hmmm... Simon -

Aint you a bit pedantic here ? By the time you have left the driver's seat from lowering the suspension on the control setting - until you reach down the pressure release screw - the car would definately had reached the low setting stops. Anyway only real hardcore non-frightened DIY'ers would reach down the relief screw while the car is on its way down

[smashymike]

Thanks for ll the info, sounds fairly straightforward stuff. So, it's nothing to do with opening the bleed nipples on the braking system? Two separate things altogether? Will changing the fluid do anything for my brakes? Or, as i'm beginning to think, will i still need to bleed the brakes in order to get rid of a) any dirty lhm at the end of the runs, b) any air still trapped? Thanks.

[Mandrake]

1) Start engine, put suspension to lowest, open 12mm pressure screw about 1/2 a turn (you’ll hear a 'whoosh' noise), wait one minute, then stop engine

Unfortunately this will not work for any anti-sink model - as soon as you open the pressure release screw the anti-sink valves both close and the suspension won't go down any further.

Might I suggest:

1) Start the engine, pressure release screw closed, put the suspension on low, wait 2-3 minutes, stop the engine, open the pressure release screw.

Thats the recommended way to depressurize an anti-sink model. The 2-3 minutes is because even though the suspension stops visibly falling after about 30 seconds, oil continues to flow back to the tank for at least 2 minutes, and you don't want some flowing back AFTER you've disconnected the tank

Regards,
Simon

Hmmm... Simon -

Aint you a bit pedantic here ? By the time you have left the driver's seat from lowering the suspension on the control setting - until you reach down the pressure release screw - the car would definately had reached the low setting stops. Anyway only real hardcore non-frightened DIY'ers would reach down the relief screw while the car is on its way down

Hi Anders,

No I'm not being pedantic at all, because as I pointed out in my post it takes a lot longer than the time it takes the suspension to visibly drop until the suspension is FULLY depressurized, and all oil that can return to the tank has done so.

On my car it takes about 20 seconds for both front and back to visibly go right down, but a further 2 minutes or more before all oil has stopped flowing back to the tank. (As proven by the clear piece of return hose I have fitted at the moment)

If you open the bleed screw before this, the anti-sink valves close and any remaining oil pressure is trapped in the suspension.

If you're just changing the LHM in the tank then you would get away with doing this, except a large portion of the oil that you would have otherwise drained from the system and replaced is still in fact trapped in the suspension, making the oil change less effective.

However if you were trying to change spheres you have a situation where there can still be a dangerous amount of pressure left in the suspension, which is why I was trying to highlight the safe and fool-proof method of depressurizing anti-sink models.

(As I see this mistake of using the old pre anti-sink methods of depressurizing still discussed all the time when nearly all Xantia's are anti-sink and require a special procedure)

Regards,
Simon

[Mandrake]

Thanks for ll the info, sounds fairly straightforward stuff. So, it's nothing to do with opening the bleed nipples on the braking system? Two separate things altogether? Will changing the fluid do anything for my brakes? Or, as i'm beginning to think, will i still need to bleed the brakes in order to get rid of a) any dirty lhm at the end of the runs, b) any air still trapped? Thanks.

Hi,

After you do your LHM change it you want to do a thorough job you can bleed the brakes as well. The first oil that comes out will be the old dirty stuff - throw this away until you get to the clean new oil which can then be recycled back into the resoviour.

Regards,
Simon

[mezuk04]

When changing the height settings you should always give the car a few minutes to stabalize and ensure all oil has returned.