C5 Mk II Suspension

[birstall]

After running my current car for a long time and not being happy with the suspension, I've found the following:
Before I set off on a journey I push the up button on the suspension, then after it has gone up, I set it back down again.
I find that this considerably improves the quality of the ride.
I previously asked my mechanic to check the ride height and he said that it was OK.
Any body got any ideas what might be the issue?

[birstall]

Update: after a long run with a packed car at the weekend, the car and suspension have been running fine .... until today.

Got in this morning and the car felt a little low at the back, Suspension did not feel good. Drove about 150 yards and realised that there were practically no brakes! Also the turbo was not kicking in. After a further 50 yards the brakes seemed to have recovered but not the turbo. I stopped the car and restarted and the turbo came back. The suspension felt OK on smooth roads but at slow speed on more rough roads I was grimacing at every manhole cover and pothole.

Getting back in for the return journey tonight the car seemed a lot better: no trouble with the brakes or turbo and the suspension seemed to have improved.

I noticed that the ambient temperature this morning was a bit cooler than it has been recently - down from the 20's to about 16 degrees C.

I'm wondering if there's a dry joint in the computer management system that might be causing these problems.

Does anyone have any similar experiences?

[myglaren]

First thing to check is the battery voltage and that it is charging OK. Sounds weird but they are very sensitive to lower than ideal voltages.
If you have the time and means, try a full reset procedure including a 24 hour battery charge. Pain in the proverbial but surprising how it can sort out strange problems.

[birstall]

OK thanks - I'll try this. I haven't tried the full reset procedure on your link so that will be interesting.

[Mandrake]

I would agree with checking for a weak battery first for many of those symptoms.

The ride being harsh over manhole covers but temporarily improving when the height is lifted up then down again could be air bubbles being drawn into the hydraulic system.

It's not an uncommon problem on a Xantia for there to be a small air leak on the feed hose from the hydraulic reservoir tank to the hydraulic pump - this doesn't necessarily cause an oil leak because there is a slight vacuum while the pump is running but air is drawn into the hose and mixed with the oil. Enough air in the oil side of the suspension can cause a very harsh crashy ride that rattles your teeth on broken surfaces...

Lifting the suspension right up then lowering it again purges out a lot of the accumulated air in the system, but depending on how bad the air leak is it can quickly return. The symptoms can also be somewhat random and affected by temperature and other factors.

I'm not sure whether the design and layout of the C5 tank and pump would be susceptible to the same problem but I can't see why it couldn't happen.

[birstall]

Thanks for the replies to this topic, all gratefully received.

Update: I tried the reboot procedure but without charging the battery. Unfortunately the procedure includes lowering the suspension to the minimum height and I've found that this sometimes triggers the problem. So after the procedure, the suspension seemed to be bad again.

I arranged to take the car in to the mechanic on Friday, but strangely enough the suspension improved on Thursday before I took it in.
The result of this was that the two different mechanics who each looked over the car and took it out for separate test drives could find nothing wrong and felt that the ride was fine.

This morning I got out the eezibleed kit that I'd bought a few weeks back and decided to take the plunge! I followed the procedure outlined in the Haynes manual for bleeding the system. I was a bit nervous about doing this, but as it turned out I needn't have been.

First thing I found was that the suspension fluid was filled right to the top of the filler neck, so I drained off nearly a pint.

I finished the procedure and I've just been out for a test run. I have to tell you that it was like driving a different car!

So very pleased with this at the moment and looking forward to a longer run to test it further.

The suspension feels much softer and there seems to be more movement, more fluidity.

I'll keep you posted to let you know if the fix is permanent.