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Discussion Starter · #1 ·
Hi

I have a Peugeot 407SW 2.0 HDI 136 (07 plate)

I have had this problem for some time where the engine temperature is not correct. Now when driving on the motorway or roads with no traffic the engine temperature does not exceed 70 deg c. When coasting downhill the temp goes near to zero which I know is not right. Now when my car is stuck in traffic for longer than 20 minutes the engine temp rises and keeps rising till it goes into the red. When this happens I put the blower on hot windows down and cool it down that way. When the traffic clears and driving normally the temp goes right down to 70 or below. My engine cooling fan does not turn on at all so I know there is a fault somewhere on that and that’s why it’s getting too hot but it doesn’t explain why it gets too cool. If there was just a fault where it gets too hot then I can say it’s the fan because it’s not turning. But because it’s not getting warm either then it makes me think there is more of a problem with the Engine temperature circuit. There could be a number of faults but I don’t know. The cooling fan is not stuck it moves freely when moved with hand. I have searched forums but could not find anything relating to this type of problem. Any help would be appreciated.

Thank you
 

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Hi...the rapid engine temp fluctuations seems strange...I think you have either a temp sensor failing or a wiring issue to look for...does it overheat or is it just the gauge shows hot?
 

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Discussion Starter · #3 ·
Hi noddy-hol the gauge shows hot and once I let it get too far and the STOP sign came on. Also it seems to be a bit heavier on the fuel which I can understand if the engine temp is not right.

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The car will over-fuel itself when it thinks it's cold to try to warm itself up.

Could it be as simple as the thermostat suck partly open: allowing too much flow when the engine is cool and not enough flow when the engine is hot?
 

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It could be an airlock in the system or a faulty thermostat. Start off by replacing the thermostat... and while you are doing it, if you notice the coolant is sludged up, the system could benefit from a flush.
 

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Discussion Starter · #6 ·
Thanks all for your help.

I have booked in my car at the garage for the mechanic to have a look at it next week. At this stage I am out of ideas but you have helped me to look in the right direction. Can anyone tell me where the thermostat is as I cannot for the life of me see where it is. I have also googled it and there is not a lot of information on the location. Not that it matters as the mechanic will hopefully fix my car but it's just a matter of interest to know where it is so I can have a quick look to see if I can see anything obvious.

Thanks
 

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Discussion Starter · #7 ·
Hi all

So I took my car to the garage on Wednesday and got it back today. I had the thermostat replaced and now it is back to where it should be. Car warms up and sitting on 90 degrees c. Doesn't go any higher and goes down a little when driving to around 85 degrees c. My fuel consumption is a lot better now and I'm very happy. All I have to do now is replace the radiator cooling fan as that is still not working. Even with the air con on it should kick in but doesn't. I know this is expensive so will be looking in scrap yards. Thanks for all your help
 

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why do you think the fan is not working?
I've got a 2.0HDI and the fan has never come on.
Air con and temps have always been ok and I've had the car for 10 years.
This includes driving in France in 40°C ambient temperatures.
 

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Well fan on mine kicks in as soon as I start AC (or regen is in progress) also temperature fluctuates from little under 90 to little over 90 in city driving or steep hills. And when I go down hill it drops a little bit. But I cannot recall that even in city driving fan turned on (maybe it did but I didnt hear it)
 

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Discussion Starter · #10 ·
why do you think the fan is not working?
I've got a 2.0HDI and the fan has never come on.
Air con and temps have always been ok and I've had the car for 10 years.
This includes driving in France in 40°C ambient temperatures.
Well reading on some threads and other forums as well as this forum, the fan is supposed to come on when the aircon is switched on even when the engine is cold. This is also a way to check if your fan is working from reading what others have said/experienced. If the car does not over heat then there is no problem. Maybe some 407's are different on the way they operate.

I am going to get my fan checked out and probably replaced and I will let you know what happens

Thanks
 

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Discussion Starter · #11 ·
Hi all,

Just an update I have managed to find a fan with the same part number that matches mine on eBay. I searched very hard to get it and it was a car that was breaking in Essex. I paid £40 for it and had it fitted. It is now working and turning as I expected. As a test I turned the AC on and soon after the fan was spinning. Now I am very happy as all the work I had done fixed all my problems. I would like to thank you all for your help and advice

Thanks :thumb:
 

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Hi all,

Just an update I have managed to find a fan with the same part number that matches mine on eBay. I searched very hard to get it and it was a car that was breaking in Essex. I paid £40 for it and had it fitted. It is now working and turning as I expected. As a test I turned the AC on and soon after the fan was spinning. Now I am very happy as all the work I had done fixed all my problems. I would like to thank you all for your help and advice

Thanks :thumb:
Thanks for letting us know you've got it sorted out and what you did to resolve the issue. Far too many people don't bother which is a pity as their fix may help others in the future.
 
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