16kHz noise when accelerating

pippu95 · 12-05-2018, 07:58 AM

I have a weird issue with my car, it makes a very high pitch squeaking noise when i am accelerating. I have analyzed the sound and it is 16kHz +-100Hz.

The sound:
-Only comes at about 1500-2000 rpm
-Only when accelerating.
-Some days it makes the sound, some days it does not.
-Does not matter if the engine warm or cold.
-Only comes when in gear
-In neutral or when clutch is pushed in it goes away.
-It sounds like it is coming from the middle of the dashboard, though it is hard to locate that high of a frequency sound precisely.
-Does not seem to change with engine rpm.
-Comes with radio head unit on and off.

I recorded the sound and boosted the noise so you can hear it clearly. In the second half of the recording i filtered the recording so that you can only hear the noise.
Here is a link for the sound.
https://clyp.it/vcow0vxi

bluewater328 · 12-07-2018, 05:37 PM

Is it like whistling or a squeal? Could be CCV. Could be Pully tensioner.

Efthreeoh · 12-09-2018, 06:45 AM

Easy. Blower motor.

pippu95 · 12-09-2018, 10:45 AM

Quote:

Originally Posted by bluewater328

Is it like whistling or a squeal? Could be CCV. Could be Pully tensioner.

Oops, looks like the link for the sound doesnt work.
Here is a new link

https://1drv.ms/f/s!ArcYWiW5a5YshCfTS69zrSjL_Nyn

The sound is REALLY high in pitch, I can barely hear it.

Efthreeoh · 12-10-2018, 11:26 AM

There's not many things in the car that can make a 16KHz sound other than tweeters. The small bearings in the blower motor rust and will sqeal, and can be related to for and aft motion of the vehicle. Next time you hear it, just turn off the HVAC system. If it stops, the the blower motor is the culpret.

pippu95 · 12-20-2018, 02:31 PM

Quote:

Originally Posted by Efthreeoh

There's not many things in the car that can make a 16KHz sound other than tweeters. The small bearings in the blower motor rust and will sqeal, and can be related to for and aft motion of the vehicle. Next time you hear it, just turn off the HVAC system. If it stops, the the blower motor is the culpret.

I have now confirmed that the sound goes out when I turn the blower off. Can i add lubrication or change the bearing without replacing the whole blower?

Efthreeoh · 12-20-2018, 08:22 PM

Quote:

Originally Posted by pippu95

I have now confirmed that the sound goes out when I turn the blower off. Can i add lubrication or change the bearing without replacing the whole blower?

You can lube it, but it is just a temporary fix. I recommend a new blower motor. There is a DIY in the DIY section with the instructions to replace it.

pippu95 · 01-06-2019, 05:37 PM

Quote:

Originally Posted by Efthreeoh

You can lube it, but it is just a temporary fix. I recommend a new blower motor. There is a DIY in the DIY section with the instructions to replace it.

Seems like a trivial task but the motor costs about 80€ so maybe i can live with the noise

12-05-2018, 07:58 AM	#1
pippu95 New Member 2 Rep 15 Posts Drives: 2008 316i Join Date: Nov 2018 Location: Finland iTrader: (0)	16kHz noise when accelerating I have a weird issue with my car, it makes a very high pitch squeaking noise when i am accelerating. I have analyzed the sound and it is 16kHz +-100Hz. The sound: -Only comes at about 1500-2000 rpm -Only when accelerating. -Some days it makes the sound, some days it does not. -Does not matter if the engine warm or cold. -Only comes when in gear -In neutral or when clutch is pushed in it goes away. -It sounds like it is coming from the middle of the dashboard, though it is hard to locate that high of a frequency sound precisely. -Does not seem to change with engine rpm. -Comes with radio head unit on and off. I recorded the sound and boosted the noise so you can hear it clearly. In the second half of the recording i filtered the recording so that you can only hear the noise. Here is a link for the sound. https://clyp.it/vcow0vxi
	Appreciate 0 Tweet Quote

12-07-2018, 05:37 PM	#2
bluewater328 Colonel 626 Rep 2,100 Posts Drives: 2011 bluewater 328i LCI sedan Join Date: Aug 2010 Location: Hawaii iTrader: (0)	Is it like whistling or a squeal? Could be CCV. Could be Pully tensioner.
	Appreciate 0 Quote

12-09-2018, 06:45 AM	#3
Efthreeoh General 17198 Rep 18,691 Posts Drives: The E90 + Z4 Coupe & Z3 R'ster Join Date: May 2012 Location: Virginia iTrader: (0)	Easy. Blower motor. __________________ A manual transmission can be set to "comfort", "sport", and "track" modes simply by the technique and speed at which you shift it; it doesn't need "modes", modes are for manumatics that try to behave like a real 3-pedal manual transmission. If you can money-shift it, it's a manual transmission. "Yeah, but NO ONE puts an automatic trans shift knob on a manual transmission."
	Appreciate 0 Quote

12-10-2018, 11:26 AM	#5
Efthreeoh General 17198 Rep 18,691 Posts Drives: The E90 + Z4 Coupe & Z3 R'ster Join Date: May 2012 Location: Virginia iTrader: (0)	There's not many things in the car that can make a 16KHz sound other than tweeters. The small bearings in the blower motor rust and will sqeal, and can be related to for and aft motion of the vehicle. Next time you hear it, just turn off the HVAC system. If it stops, the the blower motor is the culpret.
	Appreciate 0 Quote

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search