Radiator fan runs at high speed on cold

[Bmwfvr]

Hello all. lately, when I start my x5 in the morning (from cold) I notice that the fan runs at a very high speed and is very loud. it stays like this for a while. This is with AC turned off. any idea what it could be? my understanding is the fan should only kick in when coolant temp is high (thermostat in open position) or if AC is switched on.

Thanks in advance.

[Bimmer360]

Originally Posted by Bmwfvr

Hello all. lately, when I start my x5 in the morning (from cold) I notice that the fan runs at a very high speed and is very loud. it stays like this for a while. This is with AC turned off. any idea what it could be? my understanding is the fan should only kick in when coolant temp is high (thermostat in open position) or if AC is switched on.

Thanks in advance.

Is your radiator and temp sensor original, never been replaced? Mine was original from 2006 prod and recently became ridiculously loud, coolant is almost at max level, regardless if my AC was off or on and it's still loud. Replaced sensors and same issue. Figured I should replace the radiator and I did. That fixed the issue and is quiet now.

[Bmwfvr]

Originally Posted by Bimmer360

Is your radiator and temp sensor original, never been replaced? Mine was original from 2006 prod and recently became ridiculously loud, coolant is almost at max level, regardless if my AC was off or on and it's still loud. Replaced sensors and same issue. Figured I should replace the radiator and I did. That fixed the issue and is quiet now.

Yes i believe they are originals. So is it because the coolant temp is high due to a bad radiator? I checked the temp in hidden menu.. it was normal (107 C).

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[ard]

There are more than one temp sensor.


There may be more than one cooling pump and one cooling circuit (ie turbo cooling+main cooling)


When pumps start going bad, they can be INTERMITTENT. Running slow when cold, perhaps?


As a result, you can get a local loop where it is overheating, due to no flow- yet the motor is overall cool.


Just a WAG, but this isnt the old 'one pump, one sensor, just one big water pool' situation

[Bmwfvr]

Originally Posted by ard

There are more than one temp sensor.


There may be more than one cooling pump and one cooling circuit (ie turbo cooling+main cooling)


When pumps start going bad, they can be INTERMITTENT. Running slow when cold, perhaps?


As a result, you can get a local loop where it is overheating, due to no flow- yet the motor is overall cool.


Just a WAG, but this isnt the old 'one pump, one sensor, just one big water pool' situation

This is the n62 engine. One pump that is belt driven. I replaced it about a year ago in addition to the thermostat. Sensors are still originals.

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[ard]

oh, good point. You *did* list a 2007 4.8 (!!)