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Maintenance of the CX

This page contains description of some maintenance tasks I've done on my CX. Perhaps some CX owners might find this of some use.

Cooling system overhaul

My CX had a problem with cooling. It would run hot in very warm weather and when driving up long steep climbs. There's a ski resort not far from my home and the altitude up there is 1500m. When driving up there in the summer, the engine would begin overheating half way up. So I had to look into this.

I first checked whether the cooling fans operated properly. The two fans should first come on at half speed, and finally at full speed. Faulty sensors, relays or dodgy connectors could prevent this from happening. But all seemed well electric-wise.

Next, I suspected the insufficient coolant flow through the radiator (this could occur due to internal blockage), or insufficient airflow through the radiator fins (due to accumulated dirt, insects, etc.). So I decided to remove the radiator and clean it really well both internally and externally. The picture shows the Prestige with the cooling system drained, the fans removed and the radiator taken out. The matrix seen on the picture is the air-conditioning condenser.

I cleaned the radiator by hosing the matrix thoroughly with vast quantities of water. This was done several times in both directions. I also flushed and reverse-flushed the radiator with the water hose for lengthy periods of time.

Another problem was the coolant leak through the thermostat gasket. This wasn't good neither for the cooling system nor for the alternator which is located directly beneath the thermostat. The cooling system was slowly loosing coolant, and probably also the pressure, and the alternator was getting slightly wet which could damage it eventually.

The thermostat flange is held in place with three bolts. The lower two were corroded due to the leak, and I sheared them off because of that... This can be seen on the left picture.

Luckily, I was able to remove the two offending bolts without much trouble, using the vice grip plyers (picture on the right). The water pump and the alternator have previously been removed, so I had a good access to the bolts while doing this.

I have replaced the paper and rubber thermostat gaskets and this cured the leak.

I also decided to replace the water pump, as the old one was producing squeaking noise. I suspected it might not propel the water around the system good enough anymore.

The picture shows the new pump on the left and the old one on the right.

Left: I have removed the heater fan as well, to have a look at the interior heater. In order to actually remove the heater, one has to take most of the dashboard apart and pull the heater out working inside the car.

Right: I found out that the previous owner had most probably cut a hole in the firewall in the direction of the arrow. This opening under the plastic cover did not seem factory-made at all, and I think it shouldn't be there.

Left: I think I should be driving my Prestige a bit more... I found these cocoons of some fairly large insects glued onto various places of the engine. Most likely they got there before winter. The car was mostly standing still in the garage during the winter, and the first spring drive probably fried these poor things...

Right: the car is now almost back together. Only the front bumper and the lights are still missing.

Finally, when I got the car back together and went for a test-drive, I was really glad to see that the overheating problem was gone. The temperature now stays firmly within limits even in demanding conditions, like fast driving on the motorway, city traffic on hot summer days, and I can now drive up to that mountain resort as well.

It's hard to say what exactly was causing the problem; cleaning and flushing the radiator, fixing the thermostat leak and installing the new water pump all surely needed to be done, and each might have contributed its part.

The coolant temperature gauge sender

The coolant temperature gauge was not working well; it was basically just randomly jumping up and down, not indicating any reliable value at all. I found out that there was a wrong type of sender installed, and not even connected properly. The wire was touching the ground at random, and therefore the needle was jumping up and down all the time.

So I ordered the correct sender and installed it. This has fixed the problem and the temperature gauge now works correctly. The pictures show the new sender bolted into place.

When ordering the sender, I first went to a Citroen dealer. The price they quoted me was 30 EUR. Next I phoned the generic auto-parts store, which also had a suitable sender for 5 EUR... so I ordered that one. It's manufactured by FAE, who incidentally produce similar stuff (temperature senders, oil pressure switches, thermoswitches etc.) for many car makes. Their complete catalogue of parts can be downloaded as a PDF file from .

Flywheel sensors

My CX had a very intermittent starting problem. In about one attempt in a hundred, the engine wouldn't start. Such intermittent problems are usually quite difficult to trace because you can't really be sure that the problem won't happen again after a month or two.

As a precaution, I have replaced the flywheel ignition sensors. The arrows show where these are located.

Later I found out that the feed to one of the ignition coils seemed loose. I fixed that, and so far the starting problem hasn't reoccurred. Still having fingers crossed, though...

That's it for now. I didn't really need to do much else to my CX. It has been really reliable so far. The rest have just been small things like the engine oil and filter changes, replacement of a CV joint gaiter, replacement of the oil pressure switch etc.

Introduction | A few pictures | Maintenance | Repaint | Home Page