BX Sinking Feeling? | Technical matters | Back Room Forum

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Sun 29 Jun 2003 14:00

BX Sinking Feeling? - pmh

My BX (which has definitely justified its purchase thro the classifieds section) has in the recent hot weather started to increase its sink rate after parking. Is this a hot weather characteristic or just the result of another 2500 miles?

After parking for more than 2 hrs, the rear sinks to its lowest setting (settles on the mud flaps), and the front apparently rises! The rising may however be an optical illusion, I will go and measure if suggested.

On restarting after about 15 secs the nose rises further slightly, before the back rises to a normal height, and the front then settles down again after a total of about 22 secs. The auto height correctors both appear to be clear of crud and function correctly when pressure is applied to front or back respectively.

Any comments from BX experts? (David?)

I may venture to France in it if there is no suggestion of imminent permanent terminal failure! Good ride, economy (DTR) and space make a return home an attractive proposition.

pmh (was peter)

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Sun 29 Jun 2003 14:44

BX Sinking Feeling? - JohnD

Having owned a BX for eight years, what you describe is normal behaviour. Providing the suspension rises to normal height within a few minutes of the engine starting, I don't think you need worry. One of the differences between the BX and my Xantia is that on the Xantia an anti-sink valve is incorperated.

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Sun 29 Jun 2003 17:28

BX Sinking Feeling? - M.M

Peter,

I often say there is something of the animal in the different way each older BX (or Xantia) may behave.

As John says yours is absolutely fine as long as it rides well once running.

This rising behaviour can change over the years without indicating a specific problem.

How are you spheres for ride....plenty of suspension travel and the expected ride quality?

David (M.M)

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Sun 29 Jun 2003 17:36

BX Sinking Feeling? - pmh

David

Thanks for reply.

Ride is fine, and plenty of travel that auto adjusts. It is the rate of change of characteristic sink that has occurred over the last 3 weeks that has lead me to ask the question.

pmh (was peter)

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Sun 29 Jun 2003 22:05

BX Sinking Feeling? - David Lacey

My DTR (great car) was exactly the same, don't worry.

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Sun 29 Jun 2003 22:43

BX Sinking Feeling? - Berlingo

A fast sinking rear on a BX is usually caused by a leak in the brake value (brake master cylinder) It is allowing fluid to leak back into the system from the rear suspension. It is nothing to worry about as about half of BX's on the road do it. The cure is to replace the brake valve.

Mr B

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Sun 29 Jun 2003 23:57

BX Sinking Feeling? - PhilW

But I think I am right in saying that this leak does not affect the brake performance, only the rate at which the LHM leaks back to the reservoir. If your suspension is working OK then the brakes will be OK also since they have priority on LHM pressure via the flow diverter. The brake doseur valve is apparently a bit of a pig to replace anyway. My BX sinks first at the back also, rate depends on how much I have in the boot, but if yours is pumping up quickly in the morning it sounds as if it is normal behaviour.

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