C5 Suspension Shenanigans

[cachaciero]

I think I am getting closer.


It therefore seems (to me) that when the regulator switches from soft to hard mode the valve is getting stuck. The pump is then having to push really hard to overcome this to get back into soft mode. This must be happening as I am driving along, which would explain why the car is jumping randomly. Does this sound plausible?

Its jolly cold in Scotland.

Maybe I've got this wrong but I thought that only Exclusives had the H3+ hard / soft suspension. You can confirm this by the presence (or absence ) of a "sport" switch on the height controler.

But lets assume for a moment that it does have the center regulator.
Is the theory plausible? well I believe it may be. If the regulator gets stuck in hard mode then fluid would not be able to get to the struts to compensate for loss of height and the struts are isolated one from the other. The pump would presumably run until it was shut down by the overpressure limit (assuming there is one). However I believe that this scenario would almost certainly bring up suspension warnings. Such investigations that I have done with a Lexia would indicate that the system "knows" when the regulator has been commanded but not responded, although I suspect that this is only at the level of the electrovalve I can't see that it has anyway of knowing if the main spool valve has moved or not.
The other thing that gives me some doubts is that even if one assumes that the regulator is stuck with a high pressure availabe from the pump .when it does finally let go the oil will not be able to go with a big rush into the struts because of the restrictors built into the regulator it is always going to be a sedate correction to ride height. Having said all that I doubt that this is your problem

cachaciero

[Mdqagd]

This is almost certainly a problem with the rear stiffness regulator. I have disconnected the wire that switches the regulator from soft to hard and all of the problems have stopped. No sinking, no jumping. The only downside is that the rear suspension never switches into hard mode. The pump is having a well deserved rest, as it was having to work so hard to pop the stuck regulator all the time. I dont think the regulator is a serviceable item, so Im going to go on the hunt for a cheap replacement.

I'd be interested to hear if this works for you my Romanian friend.

[cachaciero]

Very interesting, have you checked that there are no volts on the connector that connects to the regulator, would be a bummer to buy a new regulator and then discover that the problem was in the BHI.

As regards servicing the regulator I reckon that if you are resourceful at hunting down seals and O rings it may be possible to breath new life into them. There are two internal control valves the electro-valve appears to be screwed in, probably with loctite or some other sealer so it would probably unscrew with a judicious application of heat. The main spool valve is accessible from the chamber under the sphere its held in against it's spring with a wire circlip remove this and it should pop out.

The big problem is testing it after a rebuild before it gets put back on the car you do really need to check that the valves work correctly.

I understand from my local dealer that failure levels on these are quite high so a secondhand one may not be any better than the one you have new ones are about £125.00

cachaciero

cachaciero