Rear End Flat, Rear suspension will not rise

[bov783]

Hi all
This is a strange one, even my local garage can't fix it !!
From flat if you start the engine and move the hight lever to normal the car rises at the front but not at the back. If you then move the leaver to the 2nd ride hight position, for about two seconds the back will rise quite quickly. You can then drive ok but it will not self level so you need to keep moving the lever for two second bursts to keep the back end up,
If you put the lever to the second hight or last position it rises fine but is too hard to drive.
I have checked for movement on the linkage where it joins the anti roll bar but it's ok. In my opinion the hight control unit must work or it would not go up manualy. The lever system is not sticking it's all well oiled. The only think I have noticed is the flow control valve sounds different. It use to click but now seems to hiss ??
Any ideas as it's liveable for me but my wife uses the car and has hit the exaust twice cos she can't seem to understand !! women!!
The car is a 2.1td auto 1996 hatch.
Kind regards
Phil

[lez]

The FDV will hiss as it ages, in my opinion, yes if there's air in the system but to be honest I find its usually just age, a bit like the tap on the kitchen sink etc.

You must have either a broken bit of the height corrector rod, a bent height corrector rod, or the height corrector itself is internally sticking and resisting moving until you apply more tension/pressure on the linkage rods and then it moves.

Bleed the brakes, because air in the rear brakes can affect ride height its been found.

[robertmnorton]

Hi Phil,clearly fluid is being diverted somewhere,path of least resistance.You will need to check which of the return lines at the reservoir is passing excess fluid to identify which component.As a '96 car it does not have a flow diverter valve, but a 6+2 pump.Meaning 2 pistons supplying suspension and brakes and 6 for the steering.That limits the problem a bit.The pressure regulator hissing confirms leakage.The fact that the rear continues to drop when driving would indicate that rear suspension pressure is being bled away.This could be the brake control valve.With the engine running and suspension up,hold a steady pressure on the brake pedal.If it continues to move downwards and the rear falls then it is likely at fault.If the pedal remains firm but the rear continue to fall then it will likely be a rear suspension cylinder or height corrector.
robertm

[Peter.N.]

I recently had a problem with my son's XM (well mine actually) It has always been very slow to rise and dropped quickly at the rear. eventually the rear n/s cylinder sprung a leak and I had to change it - that's a story in itself. When I eventually got it running again the height came up very quickly - right to the top and stayed there overnight, the only problem was it wouldn't go down.

I could find no logical reason for this until I discovered that if I levered against the height corrector linkage I could mak the car drop but it went straight up again when I stopped. I eventually concluded that while I had the suspension dismantled I bent something, probably the rod that goes from the roll bar clamp to the corrector. WhenI eventually got the clamp loose (another long story) and adjusted to the correct height all was well, in fact my son says the car has never ridden so well.

My conclusion is that fluid pressure was being lost from the cylinder that failed and also that the height was incorrectly adjusted.

Peter