Xantia Hydraulics

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Xantia Hydraulics

Post by Gavin1 » 14 May 2002, 00:58

When I start my '95 td sx Xantia it takes probably 30seconds or so for the hydraulic pressure stop light to go out. However the power steering works as soon as the engine is running but the brakes don't until the light has gone out. Also, on occasion when starting the car the whole car sinks then after a few seconds rises to normal drive height and is then absolutely fine. The brakes are also very sensitive (i'm used to citroen brakes as have 10yrs of Bx ownership). First thoughts are to clean and renue the filters / fluid esp. as I don't know the history of the car, but what confuses me is that the power steering is fine (My Bx's if anything was vaguely wrong hydraulic wise, the power steering was always the first thing to give it away, I would have thought the brakes would have priority for hydraulic pressure over the steering.

Dave Burns
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Post by Dave Burns » 14 May 2002, 01:54

Early models had about the same setup as the BX with a flow distrubutor valve, this has fortunately dissapeared on later versions.
The hydraulic pump now is actually two pumps in one housing sharing a common intake but with two seperate high pressure outlets.
There are six piston's for the steering and only two for the suspension and brakes.
As soon as the pump starts rotating it begins to deliver high pressure oil, in the case of the steering there are no compressable element's such as sphere's, so working pressure is developed very quickly.
The suspension and brakes on the other hand rely on nitrogen filled sphere's which need to be pressurised by forcing oil into them, if your hydraulic system is not in good fettle this will take time.
The output rate for the steering is much greater than that of the suspension and brakes, as during normal operating condition's they don't place high demand's on the system, they require low volume but high pressure.
The steering on the other hand requires a higher volume of oil to move the power steering ram at sufficient speeds as demanded by the driver.
With a light out time of 30 second's you ought to treat the hydraulic system to a hydraflush and filter cleaning session.
Have a gander at the colour of the LHM in the tank, it will more than likely be brown, long overdue a change.
Good luck