C5 Temperature

[c5banger]

Hi, any c5 owners had this? Couple of weeks ago lost coolant from valve on thermostat. Temp guage off the scale, STOP lamp on. Replaced valve cap with a dust cap from tyre. All ok till today. Guages off SCALE. STOP light on blower red hot NO coolant loss. Faulty stat?? Faulty sensor on end of engine 'behind' stat?? Something more sinister. C5 2001 2.0 HDi

Thanks for any help. Pete :-(

[c5banger]

Radiator is cold, by the way. :-(

 

 

Hi, any c5 owners had this? Couple of weeks ago lost coolant from valve on thermostat. Temp guage off the scale, STOP lamp on. Replaced valve cap with a dust cap from tyre. All ok till today. Guages off SCALE. STOP light on blower red hot NO coolant loss. Faulty stat?? Faulty sensor on end of engine 'behind' stat?? Something more sinister. C5 2001 2.0 HDi

Thanks for any help. Pete :-(

[Johndouglas]

Sounds as though internal pressure is forcing the cap off the bleed hole - it's only a weak plastic thread.   Simple problems first!!   Has the coolant been refilled recently?   Has the system been bled properly?

[paul.h]

Depending on answers to above, the thermostat may need replacing if it is not opening - is the radiator top hose getting hot once the engine has warmed up showing the thermostat is opening ? If the temperature is going high also the radiator fan should be running. If the coolant level is low or the air is not bled out then be careful since if the engine does overheat the cylinder head is at risk of warping. Is the cabin heater working as normal showing circulation of the coolant ? Does the engine run as normal when warming up showing the temp sensor may be ok - these can fail but the other causes of high temp should be checked first due to possible damage if the temp is high. Obviously top up using anti freeze since there is still a risk of freezing weather.

[c5banger]

cheers johndouglas & paul.h,

here goes..1st time stat bleed cap missing, expansion tank now dry, rad / top hose cold, cabin blower cold. Replaced cap on stat housing, refilled expansion bottle with anti freeze. Bled air out as far as i know. car held on 2000 revs for a couple of minutes, top hose / rad started to warm. Mechanic said stat appears ok, sensor iffy probably. Fan was running but mechanic said the water was not hot enough to warrant the warning lamps etc. No obvious signs of overheating, steam etc.

Temp gauge goes from normal, to straight off the scale, theres a beep & red light comes on + STOP lights up on speedo. (No gradual increase in temp guage)

 

ok for couple of weeks.

 

Yesterday, STOP warning lamp, temp gauge past MAX as before, BUT, NO coolant loss, bleed valve cap on stat still in place, fan running, top hose cold rad cold. cabin blower hotter than usual.

Everything ok today, temp guage usual place half way between cold / hot. not checked hose / rad for heat. Cabin blower usual temp. 

Bloody modern technology.  As a matter of interest, can you buy a thermostat as in the old days, or as the Haynes manual says you buy the housing with the new stat, complete unit??(that seems a bit strange as the stat IS removable just like the simple good old days)  Cheers Pete. :-/

[paul.h]

For now, you still have to assume the temp is right due to possible damage if ignored.

 

I would still check if any more air can be bled out, following Haynes, and that the level in the expansion tank is ok. Our C3 was difficult to get the air out, I did not have a header tank when refilling with anti freeze but jacked up the front right corner of the car so the cylinder head and cabin heater bleed screws were at a high point but lower than the water level in the expansion tank to help get the air out. 

 

Next suspect the thermostat, usually only a few £ for a new one and they do not last forever, although ones I have replaced before were opening early so the engine did not warm up. If you have the 90 or 110hp 2.0 hdi, the Citroen parts diagrams show a thermostat without the housing, opening at 83°C. Seems to be the mark 2 C5 that is part of the housing.

 

Then it could be the sensor - it is worth checking the wires to it are ok and the connector is clean anyway. If you had a code reader that showed live data, you could see the indicated temps from the sensor and see if they were as expected. Need to beware though if buying one, on diesels not all readers may work until model year 2004.

 

I would also check the water pump is not leaking - there were also on VW cars I think that had plastic impellers that fail, but I do not know about Citroen ones or whether the impeller can become loose.

 

If the head gasket had failed from the first time, there could be coolant loss seen as steam in the exhaust but then the expansion tank level would fall - had this on a petrol car once.

 

On a similar note, on our C3 on 2 occasions a year apart on the same journey (M62) that suddenly went to max temp, nothing obvious was found and later I replaced the anti freeze, thermostat and water pump as part of a timing belt change and it has not happened since. The old thermostat on testing opened at the right temp so may not have been at fault. When it did happen, first time I stopped, second time slowing down and putting the cabin heater on max brought the temp down on the gauge.

[Johndouglas]

Temp gauge goes from normal, to straight off the scale, theres a beep & red light comes on + STOP lights up on speedo. (No gradual increase in temp guage)

 

A few years ago a similar thing happened with our Xsara.   Not very time it was driven - only sometimes but there was no loss of coolant   I swopped the sender unit in the end of the cylinder head and all was well there after.

[harry bozing]

Just a little word of advice,do not keep using tyre valve dust caps as they may look similar but they do not seal efficiently,I know from experience!!. For peace of mind buy the proper cap at about 20p.hope you resolve your problem soon

[c5banger]

Thanks everyone. I'll swap stat this weekend see if I can bleed any more air out. Hope that fixes it. The mechanic last time said maybe the lost coolant caused faulty reading from sensor. Clever idea to put an electric sensor near a bleed valve!! Perhaps snow or ice had got to the sensor. I will check if wires / contacts looks clean.

***Little journey last night. Cabin blower nice n warm, guage at normal, top hose from stat to rad hot. Rad hot at top cold at bottom. ***

Cheers. Pete.

[c5banger]

Thanks everyone. I'll swap stat this weekend see if I can bleed any more air out. Hope that fixes it. The mechanic last time said maybe the lost coolant caused faulty reading from sensor. Clever idea to put an electric sensor near a bleed valve!! Perhaps snow or ice had got to the sensor. I will check if wires / contacts looks clean. ***Little journey last night. Cabin blower nice n warm, guage at normal, top hose from stat to rad hot. Rad hot at top cold at bottom. *** Cheers. Pete.

Same journey today, approx 7 miles, guage at normal, stat housing hot, top hose hot, rad hot at top & bottom. :/

My limited knowledge suggests iffy thermostat..

 Happy easter everyone.

 Pete.

[c5banger]

Little late but result is Thermostsat swapped. Still the same. Fitted new temp sensor, job done. :)

[coastline taxis]

Its never to late to post the answer to a problem as it will help other members with the same symptoms