Air bubbles in the LHM gives harsh ride?

steelcityuk · Unread post by **steelcityuk** » 16 Dec 2006, 23:48

Hi Simon,

Thanks for the info. Looks like a take your time job from your description. I think I'll wait until I've got and reconned some replacements before dismantling mine.

Bernie, sorry for the late reply! Can I get back to you on your valves as there's a guy locally breaking a VSX?

Steve.

steelcityuk · Unread post by **steelcityuk** » 17 Dec 2006, 16:58

Hi Simon,

You said - With the front Hydractive unit you MUST remove the electrovalve before the main Hydractive control block can be removed - although in your case there is no reason to remove the main control block.

Do you mean I can recon the front HA block whilst it is still on the car?

Also would you agree that I need to sort out this problem before anything else? - disconnect the front HA valve plug and check for corrosion as soon as I did this the ECU put the car in hard mode, just as it should but I also noticed that the pump was pumping all the time (strange clattery sound).When I replaced the HA valve plug the regulator went back to it's old ways of a 10 second cycle.

A weekend of good weather (for UK) wasted!

Thanks.

Steve.

Mandrake · Unread post by **Mandrake** » 17 Dec 2006, 17:24

steelcityuk wrote:Hi Simon,

You said - With the front Hydractive unit you MUST remove the electrovalve before the main Hydractive control block can be removed - although in your case there is no reason to remove the main control block.

Do you mean I can recon the front HA block whilst it is still on the car?

No, I mean you can replace the electrovalve seperately. Theres really no reason to "recon" the HA block itself - it won't be the source of your problem.

Also would you agree that I need to sort out this problem before anything else? - disconnect the front HA valve plug and check for corrosion as soon as I did this the ECU put the car in hard mode, just as it should but I also noticed that the pump was pumping all the time (strange clattery sound).When I replaced the HA valve plug the regulator went back to it's old ways of a 10 second cycle.

Well if the pump is running all the time with the plug disconneted it sounds very strange indeed! What about if you leave it connected, let the motor idle, turn the motor off (all doors closed) and after 30 seconds the electrovalve will close - does it suddenly start hissing ?

Regards,
Simon

steelcityuk · Unread post by **steelcityuk** » 17 Dec 2006, 20:31

I was assuming that the valve itself was leaking fluid internally. I've not noticed it hissing - apart from a very brief hiss click after 30 seconds. The car goes into soft mode because when I push down the front or rear of the car I can shove it all the way to the bump stops but when in hard mode I can barely shift it. Currently I have the LED and diodes connected so I think the electrovalves are working OK. I just assumed that when I disconnected one of the electrovalves and the system goes into hard mode it could make the regulator cycle even longer where as it does the opposite so I thought the HA block must have a leak like RichardW suggested. Did Richard really mean the block or the electrovalve (solenoid?).

Am I getting the wrong end of the stick?

Thanks.

Steve.

steelcityuk · Unread post by **steelcityuk** » 17 Dec 2006, 20:34

Thanks for your patience Simon.

Happy Christmas.

Steve.

steelcityuk · Unread post by **steelcityuk** » 20 Dec 2006, 21:33

Following a bit of tinkering in the dark after work I'm now thinking that the car isn't going into soft mode at the front (after waiting for the time out(. I need to have a better look at it over the weekend, maybe pulling the HA fuse or disconnecting the electrovalve plug and trying the push down test again. In soft mode the back can be pushed all the way down to the bump stops whereas the front dips a a couple of inches however this doesn't change after the ECU puts the car in hard mode (I know the car's in hard or soft mode from the LED I've fitted).

I've received the flare nut spanners today that I ordered, they look really good, just a hex end and a lifetime warranty.

Steve.

Mandrake · Unread post by **Mandrake** » 21 Dec 2006, 03:35

steelcityuk wrote:I was assuming that the valve itself was leaking fluid internally. I've not noticed it hissing - apart from a very brief hiss click after 30 seconds. The car goes into soft mode because when I push down the front or rear of the car I can shove it all the way to the bump stops but when in hard mode I can barely shift it. Currently I have the LED and diodes connected so I think the electrovalves are working OK. I just assumed that when I disconnected one of the electrovalves and the system goes into hard mode it could make the regulator cycle even longer where as it does the opposite so I thought the HA block must have a leak like RichardW suggested. Did Richard really mean the block or the electrovalve (solenoid?).

Well I can't speak for Richard, but in my opinion there is nowhere in the main hydractive control block for the pressure to leak to - there are no overflow outlets, the only way the pressure can escape is back via the height corrector.

On the other hand the electrovalve itself has an inlet and an overflow port at opposite ends. If you have a look at page 15 and 16 of the HA2 pdf you've got now, it will hopefully make some sense. Page 15 is a scale drawing while page 16 is a functional one.

Item 2 on page 16 is the needle valve pin and it seals on a seat at either end depending on whether its on or off. As long as its always sealed at either one end or the other there is no leakage. As soon as the end thats suposed to be sealing leaks, there is a direct leakage path from the high pressure supply to the overflow.

Regards,
Simon

Mandrake · Unread post by **Mandrake** » 21 Dec 2006, 03:41

steelcityuk wrote:Following a bit of tinkering in the dark after work I'm now thinking that the car isn't going into soft mode at the front (after waiting for the time out(. I need to have a better look at it over the weekend, maybe pulling the HA fuse or disconnecting the electrovalve plug and trying the push down test again. In soft mode the back can be pushed all the way down to the bump stops whereas the front dips a a couple of inches however this doesn't change after the ECU puts the car in hard mode (I know the car's in hard or soft mode from the LED I've fitted).

If you can't tell any difference at the front between the two modes, something is definately wrong. The difference between hard and soft modes at both ends of the car with a bounce test is REALLY obvious.

In the hard mode it feels so stiff that you think there's hardly any springing - thats normal due to the very heavy damping, (making it a bit difficult to judge when the strut spheres do actually need replacing) but in the soft mode you should be able to sit on the front and bottom the suspension out just like you can at the back.

Don't forget a flat hydractive centre sphere will have identical symptoms to a fault causing it to be stuck in hard mode....(switching in an extra sphere with no gas in it has no effect

) On the other hand if the problem is intermitant its not going to be the sphere.

If you're not sure if the sphere is ok or not and you don't have a spare you can try a standard accumulator sphere (if you have one) for a test. (62 bars/400cc vs 75 bars/450cc - a bit stiffer, but not by a lot, certainly drivable)

Regards,
Simon

steelcityuk · Unread post by **steelcityuk** » 21 Dec 2006, 08:34

Following the diagrams through it makes sense what you said. I think I need to remove the electrovalve and get it on the bench an see whats what. I'm tempted to remove the HA block as well and give it a good flushing out. Still the weather's taken a turn for the worse (-1C this morning) so we'll see. I'm going to get the HA manual printed off so it's easier to cross reference. Unfortunately I binned all the old spheres when I changed them. I suppose I could stump up another £20 and buy another from GSF. Alternatively I could swap front for back as a test.

What time did you post this morning BTW?

Steve

Mandrake · Unread post by **Mandrake** » 21 Dec 2006, 08:41

I didn't - 3:40pm in the afternoon New Zealand time

Regards,
Simon

steelcityuk · Unread post by **steelcityuk** » 21 Dec 2006, 09:40

Next you'll be saying the weather's nice.

Steve.

Mandrake · Unread post by **Mandrake** » 21 Dec 2006, 21:39

steelcityuk wrote:Next you'll be saying the weather's nice.

Steve.

Actually it is

Regards,
Simon

steelcityuk · Unread post by **steelcityuk** » 23 Dec 2006, 19:19

Today I took off the complete HA block and electrovalve to find out if it was the root of the problems with the harsh ride and short regulator cycles. When I took it apart here's what I found.

That little bit of 'string' is what remains of the O ring seal that fits onto the electrovalve. I found a replacement at the car spares shop in a multi pack for 65p. Since reassembling and refitting the Xantia no longer makes that hissing noise after turning off the ignition, this must have been the pressure leaking away as Richard and Simon suggested. Initially the regulator cycles went up to between 2 and 3 minutes but shortened again after a test drive. The ride was vastly improved, not quite floaty but no more crashing over pot holes and drain covers. I think tomorrow I bleed the brakes and do some more arobics and see if that improves things. I'd like to try fitting a pair of normal Xantia spheres to the front struts to see how that altered the ride.

Happy Christmas.

Steve.

Mandrake · Unread post by **Mandrake** » 23 Dec 2006, 20:32

Hi Steve,

Nice work finding the faulty o-ring ! That o-ring will indeed cause major amounts of leakage in the "off" mode if its faulty/missing. (It seperates the input pressure from the control pressure to the main block)

One comment though - are you sure the one you've put in is LHM (mineral oil) resistant and that its not designed for conventional brake fluid ?

If you're got another one, try leaving it sitting in an egg cup of LHM over a few days and see if it swells up.

The original one is green - which I'm led to believe has some special significance compared to the more common black LHM seals, not sure if its temperature rating or something else though...perhaps someone else will know.

As for the ride being much better now - don't count your chickens just yet...depressurizing the car and doing this kind of work always seems to give a temporary improvement in the ride (at least it does on my car) which then fades away after a week or two. If the ride is still just as good in 2 weeks then it will be cause for celebration

Oh, and is there any difference in the front bounce test between hard and soft modes now ? If not, you might still need to replace that centre sphere to restore the "floaty" ride...(I'd suggest that rather than putting the wrong spheres on the struts...)

Regards,
Simon

steelcityuk · Unread post by **steelcityuk** » 23 Dec 2006, 22:27

Hi Simon,

Not sure about the O ring, I do have more that I can check so I shall. Thanks for the tip. Went out about an hour ago to get some fuel and the ride is back to it's hard self again - not that surprised after reading others experiences. I think the sphere is OK, the push down test does show quite a bit of difference now and the sphere's only about 3 months old. Maybe if I can find the reason for the short regulator cycle then I can cure the ride. As noted earlier during the long cycle times the ride was good, now it's back to short cycle times it's harsh. The sit in the boot test after turning off engine doesn't make the car rise. I wonder if I should check the rear electrovalve? Now I've done some work on the hydraulics I'm a bit more confident about removing and checking parts. It will be interesting to try bleeding the regulator again and seeing if the ride improves.

Happy Christmas.

Steve.