Xantia bitron sensor and fan temperatures

stevecritchlow · Post by **stevecritchlow** » 20 Aug 2005, 12:50

I've decided to change the bitron sensor on my 2.1TD 1997 Xantia. My reason for doing this is that I'm getting high temperatures when driving, sometimes upto 100 degrees. I've changed the thermostat and antifreeze recently. The fans do work, but at 100 degrees I find that the high speed fans have not started. By removing the plug from the sensor so as the fans are on all the time, I've kept the temperature down to low 80's, even towing a caravan on long journeys.I've read on this forum that the bitron is a bit notorious for failing.
My main question is, does anyome know of a supplier for the bitron snsor other than a main agent? the Citroen agent has just quoted me £47 +vat for this part which seems a bit over the top.
Secondly,if anyone is reading this and thinking "why is he changing the sensor when the problem is obviously xyz" then please tell me.
Ta
steve

Post by **Peter.N.** » 20 Aug 2005, 13:51

I think that your real problem is likely to be that you need a new radiator. At anything over 80k it is suspect.

Kowalski · Post by **Kowalski** » 20 Aug 2005, 21:44

Your bitron unit seems to be working correctly, when you unplug the bitron sensor it goes into full speed fan mode, I don't think its supposed to make the fans go full speed until 110 or 115 degrees. It sounds like either your temperature gauge is under reading or the car is actually running hot, which could be caused by a silted up radiator as Peter suggested above. You might be able to de-silt the radiator by running a hose pipe through it and giving it a thorough washing out, if that does nothing its time for a new radiator.

stevecritchlow · Post by **stevecritchlow** » 20 Aug 2005, 22:53

thanks guys for these ideas, Can anyone else confirm exactly what temperatures the fans should be doing what at. I'm pretty sure theres nothing wrong with my guage as the car generally runs in the mid 80's. it occasionally gets very hot though, on a run or when towing.
Is kowolski correct, in saying my bitron sensor is working OK? My air-con sems to run OK if thats a hint

PeterMann · Post by **PeterMann** » 21 Aug 2005, 13:22

The mid 80s is correct running temperature for petrol engines ; one might conclude that the thermostat, temp gauge and temp sensor are working OK. Although specific and detailed information about the Bitron is elusive, it seems generally agreed that its functions have to do with the overtemp warning light and controlling the radiator fans. I had problems with false alarms on overtemp light, but the problem eventually went away. In meantime, came to understand that it is a complex electronic device that cannot easily be replaced by substitute, and there are different models of Bitron for different models, so used ones may be unsuitable.
Running at substantially elevated engine temp is a matter for concern, because of extra compression on head gasket and pressure on seals in the dreaded heater matrix.

Post by **RichardW** » 22 Aug 2005, 01:04

The fans really don't achieve much if you are travelling at over 30 mph. High temps when towing a heavy 'van at m-way speeds up hill are to be expected! As long as it doesn't get over about 105° I don't think there's much to worry about. Have you noticed a step change in cooling performance though? No other signs of HG failure (bubbles in coolant, coolant loss, system still pressurised when it's cold, system pressurising very quickly from a cold start)?
The only tests you can (easily!) make for the Bitron are to check that both fans come on low when the A/C is switched on, both come on full when the sensor is disconnected, and both come on low when the temp reaches about 87 (A/C off).
It might be worth easing the radiator backwards and checking that the gap between the intercooler and rad is not blocked with leaves.

stevecritchlow · Post by **stevecritchlow** » 22 Aug 2005, 21:13

Right, thanks everyone for the help. My fans appear to behave OK in that they come on with the AC turned on, and run at full speed with the bitron sensor disconnected. I am assuming, from the information given here, that this means the Bitron is OK??
I am concerned that my car gets upto 100 degrees (not just when towing, but also on a run). do ohters think I am right to be bother by these temperatures. It never goes above 100 degrees?
Is there any check I can do as a lay person to tell if the radiator has problems. I have played with the radiator and ensured there are no leaves or debris between it and the inter cooler. I couldn't remove the lowest pipe from the radiator however as it was corroded in. Does this point to anything?
the car has done 88k miles
Thanks for any help
Steve

DoubleChevron · Post by **DoubleChevron** » 23 Aug 2005, 06:18

Hi Guys,
I've towed a 17' caravan with my 8valve Xantia slugomatic. Even after a long hard 1st gear climb up a *very* steep hill .... Temperature only got upto 95degrees (trust me, she was working *very* hard a low speed).
Certainly it sounds like a partially blocked radiator to me. See if you can get it 'rodded'/cleaned. Even if it doesn't fix the problem, at least you can rules that issue out.
seeya,
Shane L.

pete_wood_uk · Post by **pete_wood_uk** » 23 Aug 2005, 18:04

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by stevecritchlow</i>

Is there any check I can do as a lay person to tell if the radiator has problems.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
A couple of things spring to mind. Check that the thermostat is opening properly. To be sure, you could boil it on the cooker along with a jam thermometer and watch it to make sure it opens, or for an in-situ check you could get the car good and hot while holding the top hose - it should quite quickly transition from fairly cold to bloody hot as the thermostat opens. A partial opening resulting in a sort of warm dribble might give your results.
A simple rad check is, once the thermostat has opened, run your hand all over the radiator, especially near the bottom, and make sure it's all getting hot. If it's silted up then chances are that the bottom third (or whatever) will be noticeably cooler than the rest. Needless to say, mind your hands and clothes on the moving bits while you do it...
Hope this helps.
Pete

stevecritchlow · Post by **stevecritchlow** » 23 Aug 2005, 23:14

thanks pete, what a brilliant tip about felling the rad. I do it all the time with domestic radiators, can't believe I didn't think of it
Cheers
Steve