Fan / vacuum sound on roll to stop

Kooch · 05-15-2017, 05:21 PM

I notice what sounds like fan noise or a vacuum cleaner running when I am coasting to a stop. As soon I stop, the noise stops. Seems to happen more when the car is warming up - I notice at the same few stops from my house each morning, but haven't consistently checked at all other stops. I only notice when I have the driver window cracked or open, the sound is on that side. Any idea as to the cause?

dzvero · 05-16-2017, 02:49 AM

You have no idea cars have fans?

Kooch · 05-16-2017, 05:18 AM

No, I'm pretty familiar with car engines overall - including the associated cooling systems. My point was more the timing of the running. The engine is still cold when I hear this sound. And for the fans to stop when the car stops moving vs kicking off when the car stops to keep air moving across the radiator, just seems like an odd time for the radiator fans to be running, that's all. That's why I figured it was something else. And the noise stops a split second before the car comes to rest each time. I'm not pursuing a potential problem, just more curious then anything. Thought there was a chance it may be the drilled rotors as well based on the timing, but haven't been able to narrow it down.

05-15-2017, 05:21 PM	#1
Kooch Private First Class 102 Rep 155 Posts Drives: 2016 M3 Sakhir Orange 6MT Join Date: Apr 2017 Location: Boston South Shore iTrader: (0)	Fan / vacuum sound on roll to stop I notice what sounds like fan noise or a vacuum cleaner running when I am coasting to a stop. As soon I stop, the noise stops. Seems to happen more when the car is warming up - I notice at the same few stops from my house each morning, but haven't consistently checked at all other stops. I only notice when I have the driver window cracked or open, the sound is on that side. Any idea as to the cause?
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05-16-2017, 02:49 AM	#2
dzvero Lieutenant Colonel 529 Rep 1,514 Posts Drives: 2015 M$4 F82 Join Date: Dec 2015 Location: CA iTrader: (2)	You have no idea cars have fans?
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05-16-2017, 05:18 AM	#3
Kooch Private First Class 102 Rep 155 Posts Drives: 2016 M3 Sakhir Orange 6MT Join Date: Apr 2017 Location: Boston South Shore iTrader: (0)	No, I'm pretty familiar with car engines overall - including the associated cooling systems. My point was more the timing of the running. The engine is still cold when I hear this sound. And for the fans to stop when the car stops moving vs kicking off when the car stops to keep air moving across the radiator, just seems like an odd time for the radiator fans to be running, that's all. That's why I figured it was something else. And the noise stops a split second before the car comes to rest each time. I'm not pursuing a potential problem, just more curious then anything. Thought there was a chance it may be the drilled rotors as well based on the timing, but haven't been able to narrow it down.
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