Xantia Activa - Odd temp and oil gauge behaviour!

XantiaMan · Post by **XantiaMan** » 23 Jul 2008, 14:16

Today has been pretty hot in these parts, and i've been enjoying the cold a/c, until i noticed that sitting in traffic, the temp gauge was sat at 100, crept to 110 at one point and then 120! Thats right, at the end of the scale!!!

However, i don't believe it was actually running that hot. Oil temp was close to 110c, according to the gauge.

Now, i noticed that both gauges went up at the same time. I turned the air con slider off from max down to auto and = both gauges dropped! 95 C on the coolant and below a 100 on the oil. Flick the switch back to max and an immediate 10 degree rise for both gauges.

So what am i looking at here? Unlikely to be both senders. Why would switching the AC onto full blast cause such odd behaviour?

I left the engine idling for nearly 10 mins with the A/C off Max and not once did it go over 95c nor did the oil go over 100c!

Gareth

andmcit · Post by **andmcit** » 23 Jul 2008, 14:32

I've found my Activa runs a damned sight hotter than other Xantiae and
have had this confirmed by the other Activaists on the forum here!

I've never seen anything over 80 on a Xantia before but my current car runs
100 easily which I'm still a bit troubled about; the fans are heard running
quite loudly so it may very well be the slower speed fan operation is US
and I need to follow Clogzz's reference for the fan relay fettling.

By switching the AC ON, the engine marginally runs a bit quicker and you're
not using the hot output air from the matrix so this could very well be the
direct link you're encountering.

Andrew

Post by **CitroJim** » 23 Jul 2008, 15:06

Don't worry about it overly Gareth, It has always done that

It worried me at first but the gauges are lying through their teeth

I initially checked it with a digital thermometer and found that when the gauge reads 90 the actual water temperature is 82 degrees. I have since confirmed it with the Lexia.

You will also find the temperature gauge goes up when the headlamps go on

There is a wiring problem somewhere behind the instrument binnacle and due to a) it's not an easy job, b) I know it's just a gauge problem and c) it is not consistent.

You may also occasionally see the temperature gauge play up in the other direction, reading very low and flickering for a while. It usually rights itself in short time.

Activas do run hot as Andrew says. And they will soo make the gauge climb when idling in traffic. It is vital to see that the fans are kept in good working order.

Another funny cooling problem I once had was an air lock in the oil cooler. This gave itself away by the oil temperature climbing very high but the water coolant temperature remaining unusually low. A release of the cap solved it. This happened abot 15 months agao and has never happened since. This leads me to believe the oil dumps a lot of heat into the coolant.

MikeT · Post by **MikeT** » 23 Jul 2008, 17:45

As long as it doesn't get hotter, the cooling system is doing it's job. If you'd like the engine running a bit cooler, you could try a thinner oil but I know your thoughts on that subject.

Of course, you could remove and test the sender's for accuracy, which Jim says they're not, to ease your mind?

However, I also have a vague memory of reading something about a voltage stabiliser circuit in the instrument cluster that is designed to ensure accurate gauge readings so if that fails the readings can be misleading as you load/unload the electric system.

Post by **CitroJim** » 23 Jul 2008, 18:29

MikeT wrote: However, I also have a vague memory of reading something about a voltage stabiliser circuit in the instrument cluster that is designed to ensure accurate gauge readings so if that fails the readings can be misleading as you load/unload the electric system.

That, I think, is the most likely cause of the problem Mike.

In truth Gareth, the gauge had enjoyed a long spell of being more or less OK and I'd all but forgotten about it

Next time you're over with it, we'll pop it on the Lexia when hot to confirm the temperature is in fact OK.

XantiaMan · Post by **XantiaMan** » 23 Jul 2008, 20:33

I think this is an earth problem, as the gauges will go up depending on electrical load. Putting the headlights on makes them go up, A/C switched off makes them go down. I have no worries about the actual temperatures but it does bug me a little even if its ok. With nothing on i.e lights/Air-Con the running temp is just under 90, bit less at a dual carriageway cruise. However, it could also be Mike's suggestion!

Gareth

Post by **CitroJim** » 23 Jul 2008, 21:15

Knowing Citroen wiring an earth problem is an odds-on bet

When you're next over Gareth, we'll have the instruments out and check them over for dry joints and make sure the gauges are making good contact with the PCB. I'm not sure how similar MK2 istruments are to the MK1 variety but in those, the gauge connections were not the most robust of thigs. Spring clips if I recall.

The guilty earth is most likely to be one of those under the dash

I know what you mean about it bugging you. What really bugged me at first with an Activa is how hot it appeared to run and how quickly the temperature would shoot up when stopped in traffic. That, for a Turbo CT is entirely normal but coming from a TD and their cool running, it took a bit of getting used to

My 2.1TD temperature gauge also over-reads. Clearly a disease that affects all instruments in the binnacle

DickieG · Post by **DickieG** » 23 Jul 2008, 21:17

Think yourself lucky you're not looking at a V6 temperature gauge as they read the temperature of the water entering the engine

so read something like 20 degrees cooler than the engine actually is

Stempy · Post by **Stempy** » 23 Jul 2008, 21:28

I always thought mine ran a bit cool. Now I know why, never really thought about it before.