Xsara 1.4 momentarily overheating ?
Moderator: RichardW
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Xsara 1.4 momentarily overheating ?
Hi everyone,
Some of you may remember that I replaced the head gasket on this car in January due to the common oil leak that the TU engine suffers from the cylinder head front corner.
Whilst the coolant was out of the engine I took the opportunity of replacing the thermostat with a new unit.
Well the car has been fine since with no oil leak & the coolant level has remained spot on.
The car is used by the Mrs & only travels a few miles locally.
Today when she arrived home she explained that the STOP warning light had flashed on for a few seconds then went off....this happened when the car was sitting in traffic.
I took a look & the coolant level is still spot on so I started the car & as it was still hot it only took a minute or two to get up to temperature.
Sure enough as the temp gauge hit just over the 90 degree mark the STOP light started to flash....a second or so later the temp gauge started to fall along with the rad fad kicking in (the thermostat opening)....the stop light then went out.
I let the car tick over for a while & each time the temp went up the same happened.
I’m a bit confused with this as since the head gasket was done the car has been ran up to temp a good few times & this hasn’t happened.
So I'm thinking the problem could be that the temp sender has suddenly went a bit dodgy & is registering a slightly higher temp....but the fan is coming on also....so the fan temp sensor would have to be dodgy also!
I’m suspecting that maybe the thermostat has suddenly got a little lazy & is taking just that little bit longer to open.
What do you think?
UB.
Some of you may remember that I replaced the head gasket on this car in January due to the common oil leak that the TU engine suffers from the cylinder head front corner.
Whilst the coolant was out of the engine I took the opportunity of replacing the thermostat with a new unit.
Well the car has been fine since with no oil leak & the coolant level has remained spot on.
The car is used by the Mrs & only travels a few miles locally.
Today when she arrived home she explained that the STOP warning light had flashed on for a few seconds then went off....this happened when the car was sitting in traffic.
I took a look & the coolant level is still spot on so I started the car & as it was still hot it only took a minute or two to get up to temperature.
Sure enough as the temp gauge hit just over the 90 degree mark the STOP light started to flash....a second or so later the temp gauge started to fall along with the rad fad kicking in (the thermostat opening)....the stop light then went out.
I let the car tick over for a while & each time the temp went up the same happened.
I’m a bit confused with this as since the head gasket was done the car has been ran up to temp a good few times & this hasn’t happened.
So I'm thinking the problem could be that the temp sender has suddenly went a bit dodgy & is registering a slightly higher temp....but the fan is coming on also....so the fan temp sensor would have to be dodgy also!
I’m suspecting that maybe the thermostat has suddenly got a little lazy & is taking just that little bit longer to open.
What do you think?
UB.
2006 C4 1.6 HDi 16V (92) non FAP
2001 Xsara II 1.4 LX
2001 Renault Laguna II 1.9dCi Sport Tourer
2001 Xsara II 1.4 LX
2001 Renault Laguna II 1.9dCi Sport Tourer
I think you may be right with your diagnosis of the thermostat getting lazy and not opening quite soon enough.
Alternatively I don't know about the 1.4 petrol, but on my 2.0 diesel the same single temperature sensor operates the temp gauge, temp & stop warning lights, engine ecu, and cooling fans, so a faulty temp sensor could give erroneous signs of overheating too!
Alternatively I don't know about the 1.4 petrol, but on my 2.0 diesel the same single temperature sensor operates the temp gauge, temp & stop warning lights, engine ecu, and cooling fans, so a faulty temp sensor could give erroneous signs of overheating too!
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That's a very good point, I never thought of that, I'm just assuming that there is a temp sensor for the fan like the old school cars had, hence me thinking that both of these sensors couldn't have want dodgy at the same time.nick wrote:I think you may be right with your diagnosis of the thermostat getting lazy and not opening quite soon enough.
Alternatively I don't know about the 1.4 petrol, but on my 2.0 diesel the same single temperature sensor operates the temp gauge, temp & stop warning lights, engine ecu, and cooling fans, so a faulty temp sensor could give erroneous signs of overheating too!
I know when the new thermostat was fitted that I did think that it was opening at a higher temp than the old one did going from the temp gauge. The old stat is marked at 89 degrees & so was the new one but I guess there will be a few degrees either way.Peter.N. wrote:I wouldn't have thought that 90C was high enough to set alarm bells ringing. Be guided by your temperature gauge, providing that its accurate, and ignore the warning lights.
My XM occaisionally flashes up 'Slow down excessive water temperature' when I have just started it from cold!
If the temp sensor does operates everything as nick pointed out maybe it could be that that is playing up.
I still have the old stat, I think fitting that back to the car should be my first step.
2006 C4 1.6 HDi 16V (92) non FAP
2001 Xsara II 1.4 LX
2001 Renault Laguna II 1.9dCi Sport Tourer
2001 Xsara II 1.4 LX
2001 Renault Laguna II 1.9dCi Sport Tourer
On a slightly older Citroen with 2 seperate temp sensors and a Bitron controlled fan this sort of thing was fairly normal even with a cold engine, as Peter mentions. My Xantia TD used to do it now and again.
On a mk2 Xsara though, I think its a bit more of a concern. From service citroen com it does indeed look like your car has only 1 temp sensor like mine. For it to be apparently overheating it means it either actually is overheating, or the temp sensor (or its wiring) is duff.
Even if it is just the sensor I would still be inclined to get it sorted as the same sensor will also be providing duff info to everything, including the engine ecu, which could easily affect fueling, cold starting etc.
On a mk2 Xsara though, I think its a bit more of a concern. From service citroen com it does indeed look like your car has only 1 temp sensor like mine. For it to be apparently overheating it means it either actually is overheating, or the temp sensor (or its wiring) is duff.
Even if it is just the sensor I would still be inclined to get it sorted as the same sensor will also be providing duff info to everything, including the engine ecu, which could easily affect fueling, cold starting etc.
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Yeah I also had a look on service citroen & it does only show 1 temp sensor in the thermostat housing which is correct.nick wrote:....From service citroen com it does indeed look like your car has only 1 temp sensor like mine. For it to be apparently overheating it means it either actually is overheating, or the temp sensor (or its wiring) is duff.
Even if it is just the sensor I would still be inclined to get it sorted as the same sensor will also be providing duff info to everything, including the engine ecu, which could easily affect fueling, cold starting etc.
However there is another sensor just below the housing....I remember from when I done the head gasket that this one was a right pig to disconnect the plug from.
It's #13 in this diagram:
The car isn’t here at the moment the Mrs has it with strict instructions to monitor what happens with the temp gauge etc.
What do you think the 2nd sensor (#13) is for?
I’ll double check but I’m 100% sure that there was no trapped air in the system after the head gasket was replaced. The coolant level has been checked weekly since then & has never budged so I’m assuming that all is well.myglaren wrote:Have you checked and are absolutely certain that there is no air trapped in the coolant hoses? Has the heater been checked too?
There is a bleed point right next to the temp sensor on the housing, I’ll check it tonight but I did make sure to bleed from this point when the coolant was replaced in January...I also made sure to bleed from the heater matrix bleed point.
Yeah the heater is working fine.
UB.
Last edited by uncle buck on 30 Apr 2008, 16:50, edited 1 time in total.
2006 C4 1.6 HDi 16V (92) non FAP
2001 Xsara II 1.4 LX
2001 Renault Laguna II 1.9dCi Sport Tourer
2001 Xsara II 1.4 LX
2001 Renault Laguna II 1.9dCi Sport Tourer
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Hi,
The car is home now & I have just checked & it has 2 blue sensors as shown in the diagrams I posted.
I ran the engine up to temp & once again the STOP light & the temp gauge warning light came on along with the fan....a few seconds later the temp dropped & all the lights went out.
I tried disconnecting the thermostat housing sensor (#5 diagram 1) & after a second or so the temp gauge drops to 0 with the temp & stop warning lights coming on as well as the fan.....reconnect the sensor & they all go off. I done this a few times to make sure it done the same each time.
So it looks like #5 sensor does control everything just as you said nick
I would like to know what function sensor #13 serves...its description is Engine sensor 118 degrees.
I'm starting to suspect sensor #5 is dodgy & not the thermostat.
The car is home now & I have just checked & it has 2 blue sensors as shown in the diagrams I posted.
I ran the engine up to temp & once again the STOP light & the temp gauge warning light came on along with the fan....a few seconds later the temp dropped & all the lights went out.
I tried disconnecting the thermostat housing sensor (#5 diagram 1) & after a second or so the temp gauge drops to 0 with the temp & stop warning lights coming on as well as the fan.....reconnect the sensor & they all go off. I done this a few times to make sure it done the same each time.
So it looks like #5 sensor does control everything just as you said nick
I would like to know what function sensor #13 serves...its description is Engine sensor 118 degrees.
I'm starting to suspect sensor #5 is dodgy & not the thermostat.
2006 C4 1.6 HDi 16V (92) non FAP
2001 Xsara II 1.4 LX
2001 Renault Laguna II 1.9dCi Sport Tourer
2001 Xsara II 1.4 LX
2001 Renault Laguna II 1.9dCi Sport Tourer
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- Posts: 591
- Joined: 10 Jan 2008, 19:53
- Location: UK - North east
- My Cars:
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I was going to change the thermostat back to the old one but rain has stopped play however the more I think about this problem the more I think I may be barking up the wrong tree thinking the thermostat is to blame.
Even if the thermostat was opening earlier there will be a time at some point when the fan has to operate....the way the sensor is working at present this will also operate the warning lights at the same time!
I'm not 100% sure that sensor #5 controls the temp gauge, the warning lights & the fan as surely the fan should be able to come on without triggering the warning lights!
Maybe by disconnecting the wiring to the sensor like I did triggered a fail safe somewhere to operate the fan?
Even if the thermostat was opening earlier there will be a time at some point when the fan has to operate....the way the sensor is working at present this will also operate the warning lights at the same time!
I'm not 100% sure that sensor #5 controls the temp gauge, the warning lights & the fan as surely the fan should be able to come on without triggering the warning lights!
Maybe by disconnecting the wiring to the sensor like I did triggered a fail safe somewhere to operate the fan?
2006 C4 1.6 HDi 16V (92) non FAP
2001 Xsara II 1.4 LX
2001 Renault Laguna II 1.9dCi Sport Tourer
2001 Xsara II 1.4 LX
2001 Renault Laguna II 1.9dCi Sport Tourer
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Yes, there is a fail safe which illuminates the warning lamps and puts the fan on if the sensor is disconnected.uncle buck wrote:I'm not 100% sure that sensor #5 controls the temp gauge, the warning lights & the fan as surely the fan should be able to come on without triggering the warning lights!
Maybe by disconnecting the wiring to the sensor like I did triggered a fail safe somewhere to operate the fan?