Xantia overheating

handyman · Post by **handyman** » 27 Nov 2004, 14:35

HELP! I have a 2.0i16v SX 1996 Estate, without a/c, which until now has been extremely reliable.
Yesterday, the car started to overheat alarmingly but without either of the warning lights coming on but the temp gauge showing maximum. The car is fitted with a single fan, which was not switching in.
I have checked the thermostat to see if that was the problem and also checked for airlocks in the system. All seems ok. I have also checked the fan by bypassing the single relay that controls it and found the fan working perfectly.
Where do I look next? Does any body know where the Bitron is located on this car? Does the temperature sensor located on the thermostat block control the fan or is it just to send info to the ECU? There is no sensor located on the radiator.
I have looked at all the other threads on this subject and they all seem to be related to cars with A/C.
sussexhandyman
Xantia Activa, 121K
Xantia 2.0i 16V Estate, 201K
XZ Advantage 1.6i, 122K
CX25 GTi Turbo, Mk2 Srs1, 58K

jeremy · Post by **jeremy** » 27 Nov 2004, 15:14

In what circumstances did the car overheat? At anything over 30 MPH (probably 20 in this weather) you can discount the fans altogether as the air blast should do all the necessary cooling and will exceed the fan output.
Starting with the relatively simple things first, is the radiator blocked? You will have a crossflow radiator. many years ago the flow in radiators was from top to bottom and with tanks at top and bottom. Sludge would collect in the bottom tank quite harmlessly. Modern radiators are crossflow (ie turned on a side) and sludge can collect in the bottom tubes.
Get the car hot and try and feel the radiator and see if the heat is even. If the bottom is cold and the top hot then the radiator is blocked. You may be able to clear it by removing it and hozing but a replacement may be the only cure.
How did you test the thermostat?
Bitron - keep searching - if you find one you will be unique as I think they are only fitted to A/c cars!
Fan sensor will be mounted in the tank at the cold end of the radiator. - ie opposite the pipe from the thermostat.
If its not the radiator then come back here and I'm sure you wll get further help.
jeremy

heath robinson · Post by **heath robinson** » 27 Nov 2004, 15:21

is water getting round? do the heaters blow hot and stay hot?
when cold with the cap off the expansion tank, does the water stay in there or does it get blown out as soon as the engine is running; if the latter this i think suggests a pressure that should not be there, almost certainly from head gasket leakage.

nick · Post by **nick** » 27 Nov 2004, 15:25

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by jeremy

Bitron - keep searching - if you find one you will be unique as I think they are only fitted to A/c cars!
<hr height="1" noshade id="quote"></blockquote id="quote">
After a certain point all Xantias were fitted with bitron, regardless of whether they had aircon or not.
My '97 has bitron controlled fans and temp warning lights, despite not having aircon.

jeremy · Post by **jeremy** » 27 Nov 2004, 15:30

Thanks Nick - I learn something every day - sometimes more than 1!

nick · Post by **nick** » 27 Nov 2004, 15:35

I think the reason was that by 1996-97 about 99% of new Xantias did have aircon. For the remaining few that didn't (like mine [:(]) they fitted the same bitron system, as it was probably cheaper than continuing with the non-bitron setup for just a handful of non-aircon cars coming off the production line.

handyman · Post by **handyman** » 27 Nov 2004, 19:34

Hi, me again. Thanks for the responses.
The car was being driven in heavy traffic when it overheated, ie. stop/start.
Once the engine had cooled down, I checked for any visible water leaks, water level, external blockages to radiator, etc. The rad does not have an expansion tank, neither is there a temperature sender unit fitted to the tank.
On restarting the engine, it was left idling to get hot again to test for water flow, air locks, etc. all hoses are in good condition, all got hot, as expected, including the heater matrix. There was no surge as can be expected with a blown head gasket. Flow observed through rad cap aperture showed good flow on reving engine, rad hot at both top and bottom.
Hence my original query concerning location of sender unit for temperature sensing. There are three sensors located on the thermostat housing.
If I can find this Bitron unit, does it suffer the affliction of dirty terminals, as per my CX? Or will it be unit failure given the mileage the car has done? 201,000 miles is a lot even given the longevity of modern cars. The rest of the car seems to be holding up really well, with negligeable wear on most components, a pretty good testament to Citroens ability to build good cars, when they feel like it. I can't say the same about my other Citroens, although they are all reliable.
Handyman,

np · Post by np » 28 Nov 2004, 02:28

I`ve only had the warning light come on once,in France with the caravan.The gauge went over 110c,proberly 115c before the warning light came on.This is the same on a few Pug 406`s i`ve heard about,that it comes on above 110c.

Richard Gallagher · Post by **Richard Gallagher** » 28 Nov 2004, 02:45

The Bitron unit is located behind the N/S headlight on a flat horizontal panel. However, it is partially obscured by the bumper moulding and looks as if it would be almost impossible to remove without taking the bumper off.