Needed new spheres when I bought it. very easy and cheap job to do.
Pressure regulator leaked from the right-hand mounting bracket (as did a replacement from a breakers yard)
Rear suspension arm bearings completely gone! Running on the pivot shaft alone. This can be spotted easily by looking at the rear wheels from behind. If they point in at the top, then avoid this car! Another check is listen for any creaking from the back. I managed to do both sides using a repair kit for £24 each side. Although it took me two weekends and a lot of imagination to get the remains of the old bearing out. Apparently they tend to die at about 170000 miles so take particular care if buying a BX of that age.
Heater controls don't go all the way around and the heater valve has started to leak.
The de-mister fan switch is intermittent at best, even after cleaning the control wiper. The high speed relay has never worked.
Sunroof was loose, but easily re-tightened
Bit of a misfire under heavy acceleration
Power Steering unit has gone, leaking severe amounts of fluid out of the end. This can be seen by looking at the rubber gaiter - if it's split, don't buy the car as it could be the pressure from the leaking fluid has caused it to burst like mine! £350 for a reconditioned unit with £110 labour.
I bought a Citroen because of two main reasons - 1. the famous suspension system everyone warned me not to touch and 2. they do automatic diesels! There aren't many other auto diesels to be found at an affordable price.
I love the suspension system completely. My next car will be a Xantia as they too have this type of suspension. I have never experienced such an amazing system in all my 12 or so cart-horse suspensioned years. Speed bumps are a dream! What speed bump? Off road is something to behold too! Not the usual head banging body rocking experience of a standard suspension, no - this is smooth and undulating. They should put it on land rovers!
It rolls as much as an ordinary family saloon would, but glides along on a cushion. (if it doesn't - change your spheres!)
The whole hydraulic system is actually not as scary as most people would have you believe. It's the same level of 'scariness' as a standard hydraulic brake system - except easier to fix. If it is maintained, it will not go wrong (until parts wear out of course).
It's a shame I bought a BX in the twilight of it's years because I would have loved to enjoy it for many years rather than the few short months that I have. Unfortunately I bought one that had done 170,000 miles and so got the worn out bits no-one else has changed. I would suspect a 110,000 mile BX would be great, if you can find one. They are becoming rare.
The 1.9 diesel engine is a classic, returning about 45mpg around town and about 51mpg on a motorway cruise. Although I get about 45mpg doing a steady 85 - 90mph, which it has no trouble doing.
The seats are comfy, but lack a lumber support. Also the headrests don't come forward enough to prevent whiplash in my opinion.
The single wiper is rather funky, but works surprisingly well!
The rest of the car looks nice, and the boot is flat and large.
But above all it's the whole hydraulic trick that does it for me. The brakes work off the same system and my word I have never stopped so quickly! Disc brakes all round with none-fading hydraulic pressure behind them. Marvelous.