coolant thermostat change

Blackdog · Post by **Blackdog** » 08 Feb 2010, 16:08

recently I had no heat coming from the blower..changed thermo and flushed the coolant system and I mean FLUSH...also filled up properly with header tank and bled...on some journeys she sits just fine at around 90 degrees right bang in the middle...other times when fan is switched on the temp rises big time..turn fan off and she goes straight back to normal again...occasionaly without the fan on at all the temp goes up and down...also when idling if fan is on idle speed is up just a touch fan off and idle back to normal...Im wondering if it is a faulty sensor?? or maybe she still has a block somewhere?? what do you think?

Blackdog · Post by **Blackdog** » 08 Feb 2010, 16:23

Meant to add I do now have super heating and no smell of cats...but the wavering temp gauge aint right...

spider · Post by **spider** » 08 Feb 2010, 16:53

That does sound like you have an airlock in it somewhere or (less likely) a blockage with a foreign body that's moving about.

I'd be tempted to just re-bleed it again carefully (no need to drain it just make sure its full and then re-bleed)

I thought about a faulty coolant sensor which would explain fans and gauge possibly, although that would not explain the lack of heating...

Blackdog · Post by **Blackdog** » 08 Feb 2010, 18:41

interested in your reply about radiator fans!! as I have always been suspicious of them...they never seem to come on...ok its cold weather just now but if the temp gauge was a true reading and it was that hot then I should hear them....the last xantia I had was so audible when the fans kicked in...to be honest Ive not fully checked and tested them but I did always think that this could be the problem or part of it...also foreign body sounds like a good culprit too...I reckon I need to remove the radiator flush clean and maybe replace...there was so much dirty water coming out of her when I flushed that it made me think there was a serious build up somewhere...and I found a spare sensor lodged down by the battery!! obviously the previous owner had had temp problems and tried changing a sensor...it must be a combination of fans not working and a foreign body..thanks for your post

Blackdog · Post by **Blackdog** » 08 Feb 2010, 18:45

other issue is that I can only find one bleed screw..the obvious one amongst the four pipes on top running to the matrix...I have been told there are at least another one maybe to...but hey I cant find them??? if it was a bleed problem and I have read many threads on how carefull you have to be refilling these xantias..that would save me getting a new rad!!

Post by **Peter.N.** » 08 Feb 2010, 18:59

Sounds more like an electrical problem than a temperature one, putting the heater fan on will normally cause the temperature to drop, there must be some connection between the fan load and instrument panel voltage

Blackdog · Post by **Blackdog** » 08 Feb 2010, 19:16

yeah I think its a voltage problem why would all sensors.. idle. and temp react to the fan going off or on...and temp wouldnt drop that rapidly when fan switched off if it was reading real temp!!..it would take longer to drop...

Post by **Peter.N.** » 08 Feb 2010, 21:34

I would suggest either a common earth connection or a common feed with a high resistance connection somewhere.

Blackdog · Post by **Blackdog** » 09 Feb 2010, 14:23

thanks peter n...will take a look at her at weekend

citroenxm · Post by **citroenxm** » 09 Feb 2010, 15:03

The other bleed screw is on the end of the connection pipe elbow that goes into the heater matrix, its hard to see, but if you look behind the engine were the pipes go into the bulk head, on the end of there, is another bleed screw cap..

Paul

Blackdog · Post by **Blackdog** » 10 Feb 2010, 15:39

OK Thanks Paul will have a good root around where you suggest..I reckon in the near future Im gonna replace the rad aswell its dodgy looking down the bottom when we had her up on the ramps yesterday I got a good look at it...

spider · Post by **spider** » 10 Feb 2010, 16:31

If the rad on these is like the 406 one, take care with the bottom hose. At minimum you`ll probably want a new o-ring for it.

Blackdog · Post by **Blackdog** » 10 Feb 2010, 18:10

Yeah Ive also heard that the top hose clip can be a nightmare too!

spider · Post by **spider** » 10 Feb 2010, 18:54

Top one probably will be OK, simply as you have plenty of space to get around it.