C5 rear suspension fail

[courierrelay]

My 2009 C5 estate has for a while been riding a bit high on the front. The other day the car started bouncing and when I parked the back end had collapsed. It still rises up when I use the button in the boot but as soon as I turn the car off it sinks again. The level control still raises up the front but the rear stays really low. I can hear the motor working when I raise and lower.

I connected one of those diagnostic fault finders (£20 from EuroCarParts) and its showing no fault.

It's booked in with Citroen on Tuesday for the £60 diagnosis check. Just wondering if anyone can shed any light on this problem.

Thanks

[wheeler]

A £20 Euro Crap Parts code reader is unlikely to read the suspension system.
It may even be a mechanical fault like an internal or external leak. Any signs of fluid loss? How long does it take to sink after it is turned off?

[courierrelay]

Yeah I wasn't relying too much on the code reader. Probably give the same no fault reading if the car was sitting there in flames.

Don't seem to be any signs of leaks. Probably around 4 or 5 secs to sink after turn off.

Thanks for the response

[myglaren]

I suspect a leaking electro-valve allowing fluid to return to the reservoir when the engine is off.
A diagnostic may confirm. Could be a bit of debris stuck in it if someone has been careless while working on the suspension system.

[courierrelay]

What I mean is, after the engine is turned off it starts to sink immediately, but gradual 4 secs to reach the floor

[myglaren]

Yep, faster than I would have expected but symptomatic of a leaking electrovalve. These are used to bleed fluid from the rams in order to maintain the ride height but if stuck open will allow it to drop to it's lowest position.

Try performing an extended set or Citroebics to try and clear it.

[courierrelay]

Citroebics?

[courierrelay]

Is an electro valve an expensive part? (Like there are any cheap Citroen parts)
Big labour job?

[Hell Razor5543]

Citrobics is effectively aerobics for a hydropneumatics Citroen. With the engine running you raise the car to her full height, wait a minute or two, then drop her down to her lowest setting, wat another minute or two, and then repeat several times. Then, with the car at normal height, turn the steering to full lock, wait a minute or so, opposite full lock, wait for a minute or two, then repeat several times.

What this does it to 'exercise' the hydropneumatics parts to their fullest range, and get any air bubbles that may be in the system back to the reservoir where they can escape from the fluid. Waiting between movements should allow any fine bubbles in the reservoir to leave the fluid (and not get drawn back into the system).

[GiveMeABreak]

Is an electro valve an expensive part? (Like there are any cheap Citroen parts)
Big labour job?

It depends where the fault is. There are electrovalves in the main BHI (the main electronic block that sits on top of the pump that controls the flow to and from the front and rear, and has the anti sink function. If it's one of these then you are really talking about a new BHI. It's also possible that the fluid is not being prevented from returning to the tank by the rear hydraulic block that sits attached to the rear centre spheres. If this is gone it may also need replacing.

[courierrelay]

Thanks for all the pointers guys.

Got a feeling the cost is going to be a lot. Could be a toss up between scrapping and buying another car. Fingers crossed though

[myglaren]

You could probably fit second hand parts, should it be necessary.
Try and retain the original BHI if changing the pump to avoid a mess of reprogramming as there are many variations and not all are compatible.

[GiveMeABreak]

Unfortunately the Electrovalves are in the BHI itself Steve, the pump just sits underneath. Let's see what the dealers say, I think it will be Rear Hydraulic Block or BHI - but they may cover their bases and say both!

[white exec]

Is it possible to check the rear hydraulic block for leakage, by looking at the amount of fluid being returned from it, along the return pipe . . . similar to Hydractive 2 rear blocks?

[courierrelay]

Sounds too complicated for me Chris.