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Mpi Radiator Fan Not Cutting In


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#16 Fast Ivan

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Posted 08 December 2016 - 10:20 AM

just start the car and leave it running, keeping an eye on the gauge and the expansion tank in case of overheating. The fan should come on during this test, no need to drive anywhere.

If the expansion tank starts leaking steam then make sure its not just the cap, these are prone to problems, then check that the expansion tank isn't split.



#17 Netish

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Posted 08 December 2016 - 03:58 PM

Fast Ivan , please forgive my stupidity. Do I empty the radiator and start the car . I'm sorry I don't quite understand

#18 Fast Ivan

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Posted 08 December 2016 - 04:43 PM

No, leave the radiator and the cooling system full

#19 Netish

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Posted 08 December 2016 - 04:58 PM

Ok thanks . I have done this when replaced the temp sensor and loom . But the fan didn't cut in.
As soon as I disconnected the the temp loom the fan did come on.

#20 Fast Ivan

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Posted 08 December 2016 - 05:26 PM

So what happened when you tried this?

#21 Netish

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Posted 08 December 2016 - 05:29 PM

The fan doesn't cut in . The temp guage stands steady at half . No steam or bubbles for the tank , and there are no visible cracks .

#22 minidaves

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Posted 08 December 2016 - 07:17 PM

had a few now with corroded wiring looms so fan wont cut in, down where the fan connects into the main loom


Edited by minidaves, 08 December 2016 - 07:17 PM.


#23 Fast Ivan

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Posted 09 December 2016 - 07:45 AM

The fan doesn't cut in . The temp guage stands steady at half . No steam or bubbles for the tank , and there are no visible cracks .


In that case do you have a problem?
How long have you left it running for? Either the fan will come on or it will overheat, the only other thing I can suggest is using an ACR diagnostics kit to test the fan and to observe the coolant temperature rise and note the actual temperature rather than rely on the gauge

#24 Netish

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Posted 10 December 2016 - 12:16 AM

Thanks , Ive been driving it for the last few days after replacing the temp parts and no overheating as yet. Going to see the mac on Monday to go over and make sure all is well . Thank you all for the valuable information and advice.

#25 Steve220

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Posted 10 December 2016 - 07:03 AM

This still sounds to me like a duff temperature sensor in the thermostat housing. I've had broken replacements before. If you unplug it, MEMS drops the requirement off the table and cuts the fan in, so everything from the ECU to the fan is correct. Its receiving a bad signal from the sensor. Also a silly question but what is your engine earth like? If its fraying it can often give bad readings from the engine sensors.



#26 Netish

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Posted 10 December 2016 - 09:13 AM

Where would I find the engine earth? Shall I just a a new temp sensor then ?

#27 Netish

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Posted 16 January 2017 - 10:10 PM

Evening gents,
A final update on the troubled with the fan and over heating.
So this morning and part of the afternoon I have managed to replace the water pump. After a few hours of trying I have managed to sort the radiator fan, it now cuts in when it is meant too I have taken it for a small run in traffic and all good. I will be flushed the system soon and replace if the coolent with the Evans classic coolent apparently it has a higher boiling point the the stuff I use at the moment. Thank you for all the information

#28 Honda-Mini

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Posted 26 October 2018 - 04:09 PM

Evening gents,
A final update on the troubled with the fan and over heating.
 After a few hours of trying I have managed to sort the radiator fan, it now cuts in when it is meant too I have taken it for a small run in traffic and all good.

 

So, if you don't mind me asking, what did you do to sort the fan in the end? just the water pump or other fettling? 

 

asking as i have the exact same issue and I'm two coolant temp sensors in, one thermostat, two expansion caps and minispares wiring mod to CTS done... fan comes on when the cts is open circuit (unplugged) but boils when tested stationary

 

cheers

Martyn



#29 Honda-Mini

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Posted 26 October 2018 - 04:12 PM

had a few now with corroded wiring looms so fan wont cut in, down where the fan connects into the main loom

 

minidaves... where abouts is this please? and when you find this corrosion, does the fan work at all? or just when it should be controlled by the ecu?

 

 

cheers

Martyn


Edited by Honda-Mini, 27 October 2018 - 02:00 PM.


#30 Rusty Nut

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Posted 23 September 2020 - 12:46 PM

Hello all  & @Netish - 

 

2001 MPI here overheating when stationary for 5 minutes.

 

I am having the same problem. Fan not cutting in.

Just overheats and pops the lid on the expansion tank.

Seems fine when running around the place.

Fan works fine when I unplug the sender.

What did you do to sort the temp sender problem?

 

I've drained the system and replaced thermostat with 82 degrees. 

Cleaned all the muck and grime from around the sender unit water side in the thermostat housing. It was caked which may have not helped the sender heating up properly and initiating the fan.

 

Running with tap water in for a couple of days to check how it goes and will report back but I would love to know how to check a temp sender unit.

I am guessing checking its resistance with temperature but have no figures.

 

Any help would be very welcome.






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