Bodywork, fittings, mechanical problems

Water in the footwell

Generally, you could find out where the water is coming from judging by the traces of water or by removing the footwell carpet and asking someone to pour buckets of water onto the car. If you have a sunroof fitted, this is the first place to check. There are water drain channels in the C pillars, if one or both of them become clogged, water accumulates above the headlining and comes down generally behind the B pillar trim.

Even without a sunroof it might come from the roof. Give it a try by pouring water between the roof and the roof panel side edges. It should come forward to the windshield and run down to the front wings in channels at the side of the windshield, appearing finally on the ground before the front doors. These channels are not closed from the inside, thus, if they become clogged somewhere, the water accumulates there and gets into the car, running down somewhere on the side wall near the glove compartment, getting under the carpet. In my case there was some obstacle at the lower corner of the windshield, easily cured after carefully peeling back the black rubber seal at the corner of the windshield. If it won't come off or you find no evidence of clogging, you can gain access to the problematic areas from the inside, too, by removing the A-pillar trim (sliding upwards). If necessary, you can use silicon sealants (used in kitchen and bathroom; or even better: special sealants because the common silicone one emits acidic fumes that my cause corrosion while curing) but take care to leave the water channels free and seal only where water can go astray.

Another common cause of a wet carpet in the footwell is the leaking heater matrix.

Water from the sunroof

The sunroof is not intended to be watertight, the water that gets through is drained by four drain pipes. The front ones are behind the plastic trim on the A pillars, the rear ones behind the C pillar trim and they usually get blocked. Never try to clean them by rodding or blowing into them, they can puncture or separate at the joints. Suck the blockage out of the pipes using a vacuum cleaner instead.

To gain access you have to drop the roof liner: a solid panel to which the sunroof mechanism is attached. Remove all trim panels from the A and C pillars, remove the four grab handles, the sun visors (all these items are secured by screws). Gently lever out the roof panel from the metal trim at the back and let it drop.

Watch out for the plastic clips joining the trim to the body. They are slid into a holder on the back of the trim, then they are pushed into the bodywork. To release them, get a screwdriver behind them and gently prise them out of the body. It's easy to break the holder and cannot be easily repaired, however, if you only break one or two, the remaining clips should hold the trim panel in the proper position anyway.

Jeremy RAWLING

New ignition switch with the old key

You can spare the expenses by modifying the new switch to match your original key.

The switch itself is not too complicated to disassemble. First, remove the steering column lower shroud, detach the switch wiring, turn the key to align with the arrow mark between the 'A' and 'S' positions, press the pin on the opposite side and withdraw the unit. Disassemble the lock very carefully and slowly, noting the way the internal parts are put together. There are lots of small parts inside and it would be complicated (although not impossible) to figure out how to reassemble later. Apart from that, it is a simple mechanism.

As in all similar locks (not only in cars), there are pairs of little cylinders (called tumblers) in the lock mechanism arranged in a way to only allow to turn the lock using the correctly shaped key. The pairs of tumblers are pushed against the key by small springs. If you insert the right key, all tumblers will sit in their correct position, allowing the central part [blue in the picture] to rotate while the outer part [yellow] remains stationary. However, if the wrong key is used, some of the tumblers will protrude into the other half, keeping the rotating part from turning.

Use the tumblers from your original lock, placing each into the corresponding location in the new lock: it will then match your original key. Clean the various parts and grease the moving ones as you re-assemble the lock.

If the fault lies in the electric switch of the ignition lock/switch assembly, this is even easier to repair: just separate the switch from your old lock and swap it with the one from the new lock assembly.

Re-coding the remote plip

The remote control on a BX uses a TEA5500 chip for both the transmitter and receiver. This device has ten programming inputs and each input has three possible states, connected to the high or low bus or, unusually, left unconnected. This gives 59,047 possible combinations of code.

When manufactured, all program pins are connected to both the high and low buses. To program the unit, the connecting links on the printed circuit boards are broken by drilling them out. It should be a simple matter, therefore, to re-code either the receiver or the transmitter. For reasons best known to Philips it's not as simple as it could be, the order of the pins is reversed and the logic levels have a peculiar quirk in that low on a transmitter becomes unconnected on the receiver and vice-versa.

On the picture, this connecting points are marked with letters (if the picture is not legible enough, the rows are as follows: transmitter upper row = FEDCBA, lower row = GHJK; receiver upper row = EFGHJK, lower row = DCBA) and the cut tracks are in yellow.

Step 1: To match a transmitter to a receiver (or vice versa), start with a table like this and fill in the Actual column with the words low, high and open, depending on whether the given connecting point is connected to the low or high bus or left unconnected (in this example, we'll use the setup on the picture):

Step 2: Then, copy the contents of the Actual column, row for row, to the Required column, noting that low should become open and vice versa; high remains unmodified:

Finally, use the Required column to determine how you need to set up the receiver: break the existing connection link if it is not needed any more or solder a small wire link if a new connection is required. You can go in the opposite direction as well, if you have the receiver and want to match the remote transmitter to it.

When you refit the trasmitter PCB into the case, be careful not to damage the case protrusion near the area marked with low bus.

Bob SMITH

Noisy central locking

Unfortunately, the noise is inherent in the system: the lock motors are noisy themselves (not the motor itself but rather a disengaging mechanism inside), the rods and latches attached add to this, and the whole is vastly increased by the hollow door construction.

However, you can try the following: first, check the operation of the locks in all doors, check that the rods do not unnecessarily touch or scrape against any part of the door, grease them liberally. Then you could use foam rubber plates: either put a layer between the motor and the door metal or better yet, wrap the whole motor with this material. You might even try to insulate the inner side of the trim panel where the door openings are, but don't overdo as water inside the door should still find its way out at the bottom.

But don't expect too much. I did all these and the door locks are still quite noisy. The only real solution would be to find an electrically and mechanically compatible replacement motor with a radically different disengaging mechanism. As far as I know, unfortunately, other Citroëns have similar motors, too.

Sound insulation

The original sound insulation is less than perfect in the BX. I have used 10 mm foam rubber plates in the floor and roof, 20 mm ones inside the bulkhead wall, simply layered over the existing material. Then, 4 mm asphalted plates went inside the doors and the tailgate. I've also used rubber plates on the inside of the dashboard. As a result, the engine sounds very smooth even at high revs, and the stereo just great. The difference of noise level both outside and inside the car is unbelievable.

Geir KORNELIUSSEN

In addition, there are hood soundproofing kits available made of self adhesive foam rubber plates resistant to heat, oil, gas and other aggressive liquids. They are perfect for insulating the doors and tailgate as well. You could also use rockwool (an insulating material used in house building) for the bulkhead wall, the roof and the floor.

Fitting rubber side strips

Glue them with an ordinary double-sided adhesive tape to be found in any hardware shop. Find a version which is black, about 1 mm thick and soft; this one holds the strips much better than a Scotch-like thin tape (and it is practically the same as the one Citroën used in the first place). Tesa (from Germany) produces such tapes in excellent quality.

Rear seat headrests

You don't have to hunt for rear headrests, just buy two for the front seats and cut approximately 5 cm off their legs. If the ones you find do not match your trim style or color but you have an extra pair of matching front ones, you can swap the cushions as those can be separated from the stalks simply and easily: they are secured with two Philips screws at the base of the stalk.

Andrew MINNEY

Rust above the front door hinge

Yes, this is a common fault. The reason is that this area is not strong enough and whenever the door opens against the check strap, it flexes the area which had been softened by the welding (this can be easily observed by looking at the top hinge area while opening the door against the check strap: you will see the metal around the hinge moving in and out). The hinge cracks eventually but also flexes and breaks the multilayer seam directly above.

You can repair it by removing the door and the front wing and re-welding the hinge. Weld the top seam first to make sure all three layers are strongly attached to each other. Then weld over the cracks to ensure a lasting repair work. If you grind off the excess weld, then prime and paint it carefully, the repair will be practically invisible.

You could also remove the drain grommet on the inner wing as humidity collecting in the wing can make matters worse.

Malcolm GRAY-STEPHENS