Tom Sheppard's thoughts on the BX.................................

Citroen BX

At the time of writing, The BX is the last classic citroen. Although the famous suspension sustem continues in the Xantia, and C5 models, the Bx was the last car to espouse the economy of materials that made Citroens what they were.

Penned by Marcello Gandini, famous then and now for his work for Lamborghini, the BX was deliberately styled to move away from the characteristic rounded shapes that denoted the marque's earlier products while still being instantly recognisable as a Citroen.
This article is intended both as a historical reference and a self help guide to living with a car that, like all Citroens, will become very rare.

This is a marque that requires high maintainance. Despite those who claim that they have travelled half a million Kilometres with nothing more than routine servcing, the ownership experience for many was punctuated with unpleasant and expensive surprises. The high cost of parts, coupled with the unconventional engineering approach caused the BX to become shabby quickly in the UK and despite being the best selling Citroen ever made, few good cars remain just ten years after production ceased.
It is instructive to note that any BX owners confess to an admiration for Saab 900s, another car with a reputation for unconventionality, ugliness and terrifying service costs to balance its enormously satisfying virtues.

This suggests that a BX is not quite the thing for the man in the street. In France, where their unorthodox mechanical approach is better understood, the BX is still fairly common because the French tend not to buy their vehicles as fashion or lifestyle accessories, preferring to keep their cars until they are driven into the ground. The steel, though very thin by comparison with its contemporaries is strong and resistant to corrosion and the high price of used cars means that depreciation is much lower. In 2004, a BX 19 diesel estate in good condition could be seen on a forecourt in rural France for 2,500 Euros. In Britain, similar cars in better condition are given away for nothing when they run out of MOT because it would be cheaper than scrapping it! In the last three months, a very good 1900 diesel was given away, with a suspected head gasket failure and a very fine Turbodiesel passed from one enthusiast to another without money changing hands, needing only £100 worth of routine servicing work to pass the annual test.

Owners are fiercely loyal to them, pointing out that there is no more comfortable car than a hydropneumatically suspended Citroen.
Rolls -Royce licensed the suspension system for use in their cars so they may be right.

A meeting of three owners recently revealed that they were all involved in the IT industry. This is by no means uncommon. They attract such types: technically educated people who are not frightened off by seemingly complex mechanisms find much to like about the BX. Conversely, few people who unashamedly confess to knowing "nothing about cars" will ever have considered owning one.

History:

The GS Birotor experiment, plus the tie up with Maserati to build the SM all but broke Citroen, together with the development costs of the CX. In some part, the blame can be levelled at the DS, the immortal Goddess. So advanced was this car from 1955 that it was virtually impossible to follow it while retaining the company's reputation for dramatically innovative design.
This of course was an example of history repeating itself. The Traction Avant, with its low sleek looks, front wheel drive and monocoque construction ruined "le petit Juif", Andre Citroen, who had made his money from grenades in world war one. Michelin took over the firm in the mid 1930s. Late Tractions were fitted with the hydropneumatic suspension in 1954 on the rear axle only, prior to the launch of the DS so the system was thoroughly tested before the new car was launched (although even then it was not without its gremlins.) The 2CV was the great "people's car" of France, as was the Volkswagen in Germany, the Fiat 500 and the BMC ADO15 (Mini) in Italy and Britain respectively. Unlike these though, the "Tin Snail" was a big car. When, in my early thirties, I drove one for the first time, I was amazed by how much fun it was to drive. Completely devoid of conventional performance and handling more like a dinghy than a car, I was grinning from ear to ear within ten minutes of starting off. The secret was lightness. Extremely minimalist construction over a simple platform chassis gave a spacious cabin; long suspension travel made for comfort over long distances over the notoriously poor roads of the time. Like the legendary French plumbing, the poorly surfaced roads are now a thing of the past but in its time, the 2CV was the right car for France, a large country, as the Mini was for a small one.
The success of the 2CV paid for the development of the DS.
It wouldn't be allowed these days. The investment in tooling to mass produce the hydraulic components was colossal but it laid the foundations of a system that has been in use for half a century.

Citroen absorbed its competitor, the venerable Panhard et Levassor in the 1960s. Panhard, like Citroen sold a car with an air cooled flat twin cylinder engine. Strongly built, but with a reputation for a frail engine, the Panhard fell between two stools, offering good performance and light weight. Renault had the Dauphine, though which spoilt the game for them. Panhard's engine, despite its faults, was much more powerful than the Citroen motor. Following the takeover, it was considered for a basic model of the ID, a cheaper and more conventional version of the DS but it came to nothing. The Panhard designers were put to designing the Dyane.Intended to replace the 2CV and at the same time, move it (fractionally) upmarket. It sold fairly well but couldn't supplant the earlier car.

Panhard's influence can be seen in the GS. Bearing a strong family tresemblance to the DS, the GS was fitted with a flat four, air cooled engine in a very light bodyshell, together with hydropneunatic suspension and the excellent brakes which were a hallmark of the bigger car. Camshaft wear, fragile clutches and thirst at speed combined though to make the GS a liability as it aged and as they rusted both quickly and badly, they rapidly fell out of favour. The beautiful CX was expensive to maintain and prone to niggling and occasionally serious) problems. Peugeot, France's premium marque, renowned for tough middle class cars (for which read conservative and a little lacking in flair) took over Citroen after a court battle instigated by Renault who wanted Citroen wound up.

Peugeot had bought the dessicated remains of the Rootes Group from Chrysler shortly before. Chrysler became badged as Talbot around this time and had a car called the Horizon, fitted with a Simca designed diesel engine. This would become the XU. The earlier Alpine engine, sold in France as a Simca was renowned for its noisy pushrod valvegear. The XU was fitted with an overhead camshaft and Hydraulic tappets on the petrol motors. Diesels tend to form deposits in their oil which would not be good for the hydraulic tappets and these were fitted with bucket and shim tappets instead.

As you will see elsewhere on the site, there were 1100 and 1400 engines available, based on a Peugeot design inspired by the Mini drivetrain.
These can be time consuming and difficult to mend. The 1600 and 1900 petrol engines are a better bet but the valve guide oil seals harden at around 80,000 miles making them prone to smoking. It is curable and there are ways of doing this without removing the cylinder head.

Most of the BX survivors are diesels. The engine is tough and will last for ever if the cooling system is kept in good order. The two engines are chalk and cheese. If you are planning a bank raid, avoid the 1900. It is not a getaway car. It will however cruise extremely economically, 55MPG not being unusual. Despite its poor acceleration, the car will cruise all day at 90 MPH with great smoothness and refinement. It is quiet, too.
The 90BHP 1769cc turbodiesel is a good bit quicker, only returning 45MPG which is a little unfair to it because I am assuming that you will always be travelling 10 MPH faster. This engine is just happier at 3000RPM wheras the 1900 engine is at its best at around 2600. This is a fiercer, harsher engine, never feeling as well balanced and leisurely as the bigger one. Consumption can be forced as low as 30 MPG but that is for a fully loaded Estate, averaging 100 MPH! The turbocharged engine is well mated to its transmission (although first gear is too high unless you tow with it,) and midrange torque is strong. It is no rocket ship but no embarrasment either.
The heaviest BX is the Turbodiesel Estate in TZD trim, and fitted with air conditioning. This is 1.1 tons of motorcar, a flyweight. A Xantia is around 25% heavier, sacrificing speed and economy for build quality. BXs wear their tyres and brakes slowly but you need to spend £120 every three years on replacing the spheres which are an integral part of the car's unconventional mechanism and the special hydraulic fluid, LHM, colloquially known as Vulcans' Blood, because it is neon green!

Much has been written about the Hydropneumatic system, some of it true. Links on this site will cover this in great detail but for the casual observer, the facts of life are these:
Fluid is constantly pumped around the suspension, keeping it up in the air: False.
The system never goes wrong: also false
The system is prone to leaking and it goes wrong for a pastime: not true either.
They are impossible to fix properly: uh-uh.
You cannot tow one if it goes wrong: not necessarily so.

Legends

Things do go wrong. Money tends to be thrown at the car until the owner cries enough and scraps it. This is almost always due to an absence of understanding. Experts will narrow down the fault fairly quickly to the correct part by a combination of knowing favourite symptoms and simple tests. That will be a maximum of £150, the most expensive bit being the pump. Most hydraulic sub assemblies can be rebuilt, too for a fraction of the cost of a new part.

Fluid is pumped from a tank (the Reservoir,) into an accumulator. Think of the accumulator as a battery which provides the suspension power.
The system is designed to leak internally to provide lubrication so the battery goes flat and the pump cuts in and recharges the accumulator.
If wear becomes excessive, the leakage is greater and so the pump is engaged more often. If the accumuulator sphere becomes tired, like a battery it will not hold its charge, so the pump is again engaged more often.
The self levelling system is simple enough. A pair of valves, (The Height Correctors,)one bolted to each end of the car body is set to one of four positions by a lever in the cabin. The fluid is forced into the suspension cylinders by the accumulator until the car reaches the selected height when a linkage between the suspension and the valve turns it off. Selecting a lower height simply drains fluid from the cylinders back into the tank until the valve is cut off again by the linkage. To stop the car from constantly hunting for the right height, the drainage is restricted to slow it down on its way back to the tank.
The internal leakage is also returned to the tank. That's the Hydraulics in a nutshell.
The pneumatics work like this:
The green spheres under the bonnet form the "head" of the suspension cylinder. There are two more under the back of the car, as well. Each one contains a diaphragm which divides the sphere in two. Above it, Nitrogen at high pressure forces the diaphragm downwards. Below it is a chamber into which the fluid is forced when the cylinder is filled, pushing the car upwards against the nitrogen pressure in the top of the spheres. The damper valve is built into the bottom of the sphere, where it screws into the cylinder. A bump in the road pushes more fluid into the sphere which is then expelled slowly through the damper valve back into the cylinder by the increased pressure of the gas above the diaphragm.

That is all you need to know in order to understand how it works!

If you put a sack or two of potatoes in the boot, the back of the car lowers. The linkage is disturbed and opens the height corrector. Fluid is forced in from the accumulator until the car regains the correct height.
Incidentally, if you should be fiddling around under the car and accidentally dislodge the linkage----------------------------

your next journey will be as the passenger in a hearse.

Axle stands and ramps are cheaper than funerals and are essential for Citroen maintainance.

Given time, (Years,) the nitrogen slowly escapes through the diaphragm reducing the pressure in the upper part of the sphere. This is known as a flat sphere and it is the reason for a harsh and bouncy ride. (It is possible to reinflate the spheres if the pressure has not fallen too far. In countries such as Australia where parts are scarce and expensive, this is common practice but spheres are cheaply available in the UK.) The same thing happens to the accumulator which has its own sphere. If the pump can be heard operating more frequently than once every thirty seconds, check the fluid level first but reckon on changing the accumulator sphere. From here on in, I'll refer you to the links page to check out the BX DIY site.

Much of this system runs at high hydraulic pressures. Pipes can (and do) rust out. Replacements are available but some are tricky to fit.
The pipes on post 1990 cars have plastic coatings and last longer. Bear it in mind if choosing a car.