Greetings from Spain!

[Ferness_Bay]

Hi, my name is Denis and I'm from Spain. I've been driving a 1998 2.5 TD SX Citroën XM for 8 years. I came here looking for some info that could help me fixing a temperature issue with the water cooling system: when the car is a little bit pushed it rises up easily to 100ºC, and if it's further pushed, e.g. a steep road, it rises to 110 and even a little higher.

I'll be checking out the forum topics to see if there's already any stuff related to my car's issue; should I not find it, I'll create a new topic in the hope of someone could bring some light to it.


I'd like to apologize in advance for any mistake commited while using English; my skills are not as good as I'd want them to be, and much less the technical concepts


Thanks for your attention and see you around!

[Dean]

Hi Denis

Your English is brilliant, better than mine I would say!
Have you checked the usual suspects, I believe the 2.5 has two thermostats, also do your cooling fans work?

D

[djg]

Chris (White Exec, who happens to be a Briton living in Spain) described it in detail in a topic very recently, if only I could remember which one it was...

I think: viewtopic.php?f=5&t=8517&start=10" onclick="window.open(this.href);return false;

[Ferness_Bay]

Hi again! Concerning my English, I have to give some credits to Mr. Google He's very helpful with vocabulary.

About those thermostats and checkings, that's what I'm working on with my father. We're trying to locate the one that might be causing trouble according to him (not sure if the one we're looking for is called thermostat or temperature switch), but since we have nowhere to properly work with the car for a long term time (just a shared garage), we can not just start disassembling pieces, so we must be sure when we "touch" anything.

Referring to the post that djg linked, it definitely contains plenty of detailed info, but yet I can not find anything about this particular part; neither did I on the forum archive.

Should I create a new topic with my own issue and car behaviour, or post a reply on that post that djg linked?

Thanks a lot!


P.S. I found a picture of the part I'm looking for (the one with blue connection placed in the side of the radiator) in this post viewtopic.php?f=19&t=8593&hilit=temperature+2.5 but I don't know if it can be found in the same place on the 2nd series cars, or even if it is really the one I'm looking for at all.

[Peter.N.]

John will probably be along shortly, he is the expert on 2.5s.

Peter

[xmexclusive]

That large blue radiator temperature sensor is not fitted to 2.5 XM's.
The 2.5 engine ECU will normally keep full control of coolant temperature.
The range should be 95 to 100.
If the temperature gets higher and runs up to 110 my first check would be to see if the engine cooling fans are running correctly.
If the temperature gets much above this level the engine ECU will switch into first stage limp mode.
Limp mode limits engine power to try to reduce coolant temperature.

Cooling fan checks:
With engine off remove or reach through the nose cone and try spinning each of the two cooling fans.
I have found these fans can degrade with age or corrosion and lock solid.
The fans work as a pair so with one failed 110 instead of 100 is a typical max running temperature.
Next check the cooling fan fuses, these are the two individual 40A MAXI fuses clipped alongside the engine bay fuse box.
Then check the three cooling fan relays, these are fixed behind the headlight that side of the car.
Then run the engine with the car static and watch the temperature rise.
When it reaches 100 you should see both fans should cut in an run.

John

[djg]

John described the locations but you might want to download the circuit diagram PDF from its similarly named topic, it shows both the circuits and the locations.

I also have images on my site that might help with the identification of those parts:

http://citroen.tramontana.co.hu/en/elec ... -part-list" onclick="window.open(this.href);return false;

[Denis M.]

Hello, and thank you for your help.

I have checked the fans and they seem to be OK: they both spin, and both the relays and the fuses are fine too. When it reaches 98º the fans start working. According to what you are telling me I should asume that I shouldn't get worried because it gets to 100º, but I have some questions:

    -I understand that this car has a very feeble engine head (It already had to be replaced one time): getting to 100 everytime the car is a little pushed wouldn't get the engine head or the head gasket progressively damaged? Should I install a more sensitive sensor that would make the fans start cooling at a lower temperature and try to keep it working at 90º all time?
    -In a spanish forum I read that this temperature sensors are not accurate at all, and one person said that the real temperature of his car water (manually measured with an infrared thermometer) was 10º less than what the car gauge was showing. What can you tell me about that? I will try to do this measure as soon as I can.

Now some concerns about a steep winding road I drive through sometimes and about the 2nd speed of the fans:
    -This road takes you from point A: 700 masl to point B: 1130 masl. It is a 5 km path, driving during approx. 7 minutes at 50 km/h and less; 3rd gear half the way and 2nd gear almost the rest of it. My father told me that it's completely normal that going through that the car rises higher than 110º because the fans don't have time to cool it up (besides, when I drive through this road the outside temperature is around 25º).
    -Even asuming that it is normal that the car gets so hot due to the toughness of the road I still don't know if the 2nd speed of the fans works properly, or if there's some kind of failure that prevent the car from getting into limp mode: is there any way to test that other than pushing the car to such temperature?

If the cooling system is working completely fine and I'm just paranoid I still have to refill the coolant seriously often, but I can't see that it leaks. I am going to replace the coolant tank cap, use a cooling cleaner and keep a further eye in order to find possible undetected leaks. I'll keep you posted.

Thanks again.

Denis

[djg]

I never heard the 2.5 to be anything like weak and sensitive in the head..

I have a similar problem now with coolant loss and I already tried two caps, without results. I suspect the expansion tank itself now. Try to listen for a hissing sound from near the cap after a hot run.

The sensors can be tested out of the car (submerging into heated water) but I don't think it would be nearly as simple in situ. But as long as they switch when the temp gauge shows the appropriate temperature, I wouldn't worry.

[xmexclusive]

The THY 2.5 engine has a reputation for valve seat cracking of the cylinder heads.
It is believed to be caused by air locks left in head waterways due to not using the header extender when refilling the cooling system.
That is on full drain down and refill, not casual topping up of lost coolant.
Only if the header tank is totally empty does the extender need to be used.
If not available one can be made from a large plastic bottle.
There is a set procedure which takes close on 30 mins.
I estimate roughly half the cylinder heads are found to have these cracks when a new head gasket is needed.
To date most of these cracked heads are scrapped and replaced at some considerable expense.

John