Whine that follows rpm. N52.

e91-330xi · 04-20-2019, 07:05 AM

Hello, this noise started a couple of months ago.
No codes have been thrown, and it has gotten better/worse.

I think i comes from OFH/alternator part of the engine, but its hard to hear.
Its like its lagging behind the rpm
Anyone recognise the sound?

And sorry for the low volume

Phyrexia · 04-20-2019, 11:46 AM

My car has made this noise the whole time I've owned it. I thought it might be the AC compressor. What else would spin at a different rate than the motor?

Phyrexia · 04-20-2019, 12:22 PM

Sounds like this, eh?

e91-330xi · 04-20-2019, 12:31 PM

Quote:

Originally Posted by Phyrexia

Sounds like this, eh?

yes, exactly like that.

in the summer i have whine from the ac, but it was off when i recorded the video.

maybe theres a bearing thats always engaged on the ac compressor?

rjahl · 04-20-2019, 12:51 PM

Sounds like the overrun clutch on the alternator. I little noisy but about normal.

Alternator is fitted with a one way clutch on the pulley.

e91-330xi · 04-20-2019, 02:56 PM

Quote:

Originally Posted by rjahl

Sounds like the overrun clutch on the alternator. I little noisy but about normal.

Alternator is fitted with a one way clutch on the pulley.

is that serviceable or do i need to change the alternator completly?

shuotong · 04-21-2019, 12:05 AM

Quote:

Originally Posted by e91-330xi

Quote:

Originally Posted by rjahl

Sounds like the overrun clutch on the alternator. I little noisy but about normal.

Alternator is fitted with a one way clutch on the pulley.

is that serviceable or do i need to change the alternator completly?

Hmm, just want to tell my story, my alternator dies at Montreal and I live in Toronto, roadside assistance only covers 250km and the rest 150km are...well, like a electric car

I ask my mother to pick me up at the drop off point and charged my battery using her Accord and then drives the rest 150km, it was a nightmare: battery only lasts 15 minutes, takes 45 minutes to recharge...
If the alternator has some problem better to replace it just in case.

rjahl · 04-21-2019, 08:47 AM

Quote:

Originally Posted by e91-330xi

Quote:

Originally Posted by rjahl

Sounds like the overrun clutch on the alternator. I little noisy but about normal.

Alternator is fitted with a one way clutch on the pulley.

is that serviceable or do i need to change the alternator completly?

You may find a replacement pulley but i would not bother. It sounds pretty minor at this stage. You might find some way to clean it.

I had a terrible time resolving my accessory belt whine and would never install anything but OEM belt, tensioner or alternator again. My E85 /N52 had very little soundproofing and anything put perfection from this area drove me nuts.

At one point, I hade an aftermarket belt that sounded like a supercharger under the hood. Parts store asked me run it for a while and let it "break-in". LOL

juld0zer · 04-22-2019, 05:04 AM

Did you recently do an oil change?

e91-330xi · 04-22-2019, 07:19 AM

Quote:

Originally Posted by juld0zer

Did you recently do an oil change?

Yes but the noise was present before that. I first thought that it might have been the oil filter
Put No change in sound.

e91-330xi · 04-22-2019, 07:21 AM

Quote:

Originally Posted by rjahl

You may find a replacement pulley but i would not bother. It sounds pretty minor at this stage. You might find some way to clean it.

I had a terrible time resolving my accessory belt whine and would never install anything but OEM belt, tensioner or alternator again. My E85 /N52 had very little soundproofing and anything put perfection from this area drove me nuts.

At one point, I hade an aftermarket belt that sounded like a supercharger under the hood. Parts store asked me run it for a while and let it "break-in". LOL

I am going to change the belt and tensioner next month, hopefully that Will sort it out.

Is it possibly to run the engine without the belt? So i can be sure its something connected to it that makes the Noise.

juld0zer · 04-22-2019, 07:47 AM

Quote:

Originally Posted by e91-330xi

I am going to change the belt and tensioner next month, hopefully that Will sort it out.

Is it possibly to run the engine without the belt? So i can be sure its something connected to it that makes the Noise.

Yes, just make sure the belt is removed completely and no tools left in the way for the brief test.

Volasko · 04-24-2019, 12:19 PM

I've had this noise since I first got my PE and was revving the crap out of it to hear it. I always thought it was the syncros in the transmission. Anyways 180k km's later and I get the same noise, plus everything else still works like it should. I wouldn't chase or stress about this any further.

gT-BMW · 04-24-2019, 02:16 PM

Quote:

Originally Posted by Phyrexia

Sounds like this, eh?

I just did this to my 325i and noticed the same whine. I didnt even know that was there until i rev my engine like that!

04-20-2019, 07:05 AM	#1
e91-330xi New Member 2 Rep 16 Posts Drives: BMW E91 Join Date: Mar 2019 Location: Sweden iTrader: (0)	Whine that follows rpm. N52. Hello, this noise started a couple of months ago. No codes have been thrown, and it has gotten better/worse. I think i comes from OFH/alternator part of the engine, but its hard to hear. Its like its lagging behind the rpm Anyone recognise the sound? And sorry for the low volume
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04-20-2019, 11:46 AM	#2
Phyrexia Resident Pedant 503 Rep 792 Posts Drives: '15 335i 8AT Join Date: Nov 2017 Location: Limbo iTrader: (1)	My car has made this noise the whole time I've owned it. I thought it might be the AC compressor. What else would spin at a different rate than the motor? __________________ '15 F30 335i 8AT Estoril II/Black (12.218 @ 114.94mph) MHD Stage 2+ 93 / XHP Stage 3 / M-Goodies / K&N Filter / ER CP / CSF IC / NGK 97506 / ER DP / Michelin A/S 3+
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04-20-2019, 12:22 PM	#3
Phyrexia Resident Pedant 503 Rep 792 Posts Drives: '15 335i 8AT Join Date: Nov 2017 Location: Limbo iTrader: (1)	Sounds like this, eh? __________________ '15 F30 335i 8AT Estoril II/Black (12.218 @ 114.94mph) MHD Stage 2+ 93 / XHP Stage 3 / M-Goodies / K&N Filter / ER CP / CSF IC / NGK 97506 / ER DP / Michelin A/S 3+
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04-20-2019, 12:51 PM	#5
rjahl Colonel 996 Rep 2,287 Posts Drives: Z4 35is Join Date: Jun 2011 Location: Tampa iTrader: (0) Garage List 2012 Z4 35is [0.00]	Sounds like the overrun clutch on the alternator. I little noisy but about normal. Alternator is fitted with a one way clutch on the pulley.
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04-22-2019, 05:04 AM	#9
juld0zer Lieutenant Colonel 480 Rep 1,600 Posts Drives: Prev 135i 7DCT, Now 130i 6sp Join Date: Jul 2016 Location: 2153 iTrader: (0)	Did you recently do an oil change?
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04-24-2019, 12:19 PM	#13
Volasko Colonel 704 Rep 2,603 Posts Drives: 06 330i E90, 18 530xe G30 Join Date: Dec 2010 Location: Toronto iTrader: (2) Garage List 2018 BMW 530e M Sport [9.00] 2006 BMW E90 330i [8.28]	I've had this noise since I first got my PE and was revving the crap out of it to hear it. I always thought it was the syncros in the transmission. Anyways 180k km's later and I get the same noise, plus everything else still works like it should. I wouldn't chase or stress about this any further. Last edited by Volasko; 04-25-2019 at 08:01 AM..
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