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Old 7th October 2018, 19:24   #11
bilsan330
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Default 75T Estate Electric cooling Fan keeps coming on.

Ok thanks..never knew this existed.

I will give it ago tomorrow. However I just want to say as far as I know the car does not run hot I have been all over Europe in it this year...but if the fan is triggered somehow when I stop the car and turn the ignition off the fan stops.On starting the car again it stays off. Surely if the car was hot the fan would come back on again at that stage..but it does not..I can go miles before it happens again.
I just want to add when the fan comes on it stays on forever until I turn the ignition off.

Bill
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Old 7th October 2018, 19:28   #12
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On the face of it you have an unusual set of symptoms Bill which is why we need to begin by collecting data.

Has anyone been working on your cooling system recently?

Simon
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Old 8th October 2018, 10:07   #13
bilsan330
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Default 75T Estate Electric cooling Fan keeps coming on.

Ok here it is....

From a cold start I did a journey of 75 miles.First part motorway for about 30 mins engine temp fluctuates from 79/82. no problem. off motorway got into town traffic for about 15 mins then fan came on went up to 128. Went through the procedure of turning the ignition off waited 5 mins turn back on temp 81 carried on for about 40 mins at this temp then same thing happen again...

Strange it never seems to happen on the motorway....From this I dont think the car is running hot.

Over to you

Bill
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Old 8th October 2018, 13:38   #14
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Doesn't sound like the Double Thermostat Jeopardy and a 128C reading seems very spurious, especially dropping to only 81C in five minutes after shut down. At a real 128C, the head would be half cooked. You haven't mentioned the state of the coolant so far. Can we assume it's at the correct level and never falls?

Did you notice whether the temperature gauge dropped off the bottom when this event happened?Loss of sensor signal would mimic much of what you've described and could result from a poor/slack connection or fatigued wiring from it. I'd suggest checking the sensor connector, maybe give everything a clean and ensure it fits together tightly. The sensor is to the right end of he head as you look at it, by the min coolant outlet.



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Old 8th October 2018, 16:29   #15
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Default 75T Estate Electric cooling Fan keeps coming on.

firstly T Cut thanks for the photo at least I know where the sensor is...had a quick look seems ok from the outside...are these easy to change.??? would you suggest I start by changing this.

The temp gauge drops to zero when the fan comes on...I then wait 5 mins start the car and every thing is back to normal the gauge always returns to half way. thats how we carry on until next time. as explained previous over the course of 60 miles the fan can come on 2/3 times or not at all.

Regarding the water level I always check the water level every morning before i drive...sometimes it needs topping up but I cant see any visible leaks..its had a compression test and new inlet manifold gasket.

Thanks
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Old 8th October 2018, 17:02   #16
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Quote:
Originally Posted by bilsan330 View Post
The temp gauge drops to zero when the fan comes on
That's a pretty good indicator that the sensor signal is lost. This causes the ECU to trip on the emergency cooling - hence the fan roaring when the engine's not in overheat. I suspect the 128C diagnostics reading is part of that response.

Quote:
...I then wait 5 mins start the car and every thing is back to normal the gauge always returns to half way.
I'd suggest that's either a meachanical effect on a weak connection due to the engine vibrations at startup. Or, the sensor itself is failing. Though that's pretty rare, I guess it can happen.

Quote:
would you suggest I start by changing this.
Why not - it won't dent your wallet and may cut a long story short.

Quote:
Regarding the water level I always check the water level every morning before i drive...sometimes it needs topping up but I cant see any visible leaks..its had a compression test and new inlet manifold gasket.
There's definitely a small leak somewhere. Internal or external, they're pretty common in this engine.

EDIT: You'll need to run the Demist Test for low speed fan operation once you get the signal issue fixed. We haven't confirmed that the low speed resistor is OK.

TC

Last edited by T-Cut; 8th October 2018 at 17:07..
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Old 8th October 2018, 19:28   #17
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Default 75T Estate Electric cooling Fan keeps coming on.

Thanks T Cut thats very informative.

I will try and get a sensor are they very easy to fit.,..or is it a garage job.

Would you suggest put some rad weld in.

Thanks

Bill
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Old 8th October 2018, 19:35   #18
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Quote:
Originally Posted by bilsan330 View Post
... engine temp fluctuates from 79/82.
Thanks Bill. That temperature is much too low. The thermostat doesn’t open until 88 degrees! You have a leak somewhere. Your cooling system is behaving like a kettle!
Edit: Whoops! Somehow I overlooked your evidence of the gauge dropping to ‘cold’. Yes, follow T-Cut’s suggestion to suspect the coolant temperature sensor.
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Originally Posted by bilsan330 View Post
Would you suggest put some rad weld in.
Noooooo! Don’t put ANY additives in. Find the leak and fix it properly.

Simon
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Last edited by SD1too; 9th October 2018 at 07:08..
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Old 8th October 2018, 21:39   #19
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Chaps, the MEMS3 default temperature reading when the CTS goes open circuit is minus 128 degrees Celcius, and the fan is instructed to run at full speed as a failsafe

So T-Cut is on the money, I would suspect nothing more than a poor connection to the coolant temperature sensor, so take it off, check and clean the contacts then reconnect.

Brian
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Old 9th October 2018, 15:54   #20
bilsan330
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Default 75T Estate Electric cooling Fan keeps coming on.

Hi Guys....

Now here is something strange..T cut sent me a photo of the sensor location..So I had a look did not get it out but generally wiped it and felt the wires going in...

Can you believe I travelled my route again today of 60 miles and the fan did not come on..Can it be that simple I am waiting with bated breath tomorrow to do the same trip...

Watch this space...

Thanks every one

Bill
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