Rattling sound when engine cold and heat is on

claasmi · 01-11-2016, 06:08 PM

2011 128i. Since its been getting colder I get an awful sort of plasticky rattling sound from behind the dash for the first couple minutes after I start the car and have the heat on. The speed of the rattling is constant and doesnt change with the fan speed. If I turn off the fan it goes away immediately. It also goes away completely after the car has warmed up. It also it seems to get stronger when I am breaking or turning.

Any ideas what this could be?

RoundelM3 · 01-13-2016, 08:55 AM

The HVAC blower (fan) is notorious for failing in the E8x and E9x cars. Mine would "squeak" when on low speed and during braking and cornering. Only thing you can do is replace it or turn the radio volume up. Could be the bearings are tighter due to the cold, but very likely you'll have to replace the blower.

TwinTurboXI · 01-13-2016, 09:52 AM

Quote:

Originally Posted by roundel335

The HVAC blower (fan) is notorious for failing in the E8x and E9x cars. Mine would "squeak" when on low speed and during braking and cornering. Only thing you can do is replace it or turn the radio volume up. Could be the bearings are tighter due to the cold, but very likely you'll have to replace the blower.

Good info here, this could be the culprit of my "squeal" when I start my car on cold days. Occasionally I'll also have a slight rattle as well.

Does the blower fan actually fail? Or does it just make noise?

Mr Rooty Von Tooty · 01-13-2016, 09:53 AM

If they make noise, they'll eventually fail!

RoundelM3 · 01-14-2016, 07:10 AM

Quote:

Originally Posted by TwinTurboXI

Good info here, this could be the culprit of my "squeal" when I start my car on cold days. Occasionally I'll also have a slight rattle as well.

Does the blower fan actually fail? Or does it just make noise?

When it starts to make noise, I consider that a failure.

Yes, it still functions, but not very well. The motor runs, but the bearings get worn out and/or the fan comes in contact with something, which usually happens at lower speeds, and it comes and goes, not always constant.

TwinTurboXI · 01-14-2016, 08:52 AM

I'm not fully convinced this is my issue yet, but it certainly could be.

RoundelM3 · 01-15-2016, 08:45 AM

If you turn the ventilation fan off and the noise stops, things are pointing to the fan blades or the motor. Mine seemed to do this mostly in cold weather. I don't recall the noise in warm weather driving at all.

MightyMouseTech · 01-15-2016, 09:02 AM

And replace it before the blower motor bearing dust gets on the evaporator and corrodes it out.

01-11-2016, 06:08 PM	#1
claasmi Private 37 Rep 56 Posts Drives: 2011 128i 6MT Join Date: Jun 2015 Location: Toronto iTrader: (0) Garage List 2011 128i [0.00]	Rattling sound when engine cold and heat is on 2011 128i. Since its been getting colder I get an awful sort of plasticky rattling sound from behind the dash for the first couple minutes after I start the car and have the heat on. The speed of the rattling is constant and doesnt change with the fan speed. If I turn off the fan it goes away immediately. It also goes away completely after the car has warmed up. It also it seems to get stronger when I am breaking or turning. Any ideas what this could be?
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01-13-2016, 08:55 AM	#2
RoundelM3 Major General 1837 Rep 6,990 Posts Drives: 15 F80 M3, 22 G01 X3 30i Join Date: Apr 2010 Location: Clayton, NC iTrader: (2) Garage List 2022 BMW X3 [9.83] 2015 BMW M3 [6.50]	The HVAC blower (fan) is notorious for failing in the E8x and E9x cars. Mine would "squeak" when on low speed and during braking and cornering. Only thing you can do is replace it or turn the radio volume up. Could be the bearings are tighter due to the cold, but very likely you'll have to replace the blower. __________________ 2015 F80 ///M3 Sedan 7DCT Tanzanite, 2022 X3 sDrive30i 8AT Brooklyn Grey
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01-13-2016, 09:53 AM	#4
Mr Rooty Von Tooty Banned 117 Rep 460 Posts Drives: 2013 BMW 135i M-Sport Join Date: Jul 2015 Location: Dayton, OH iTrader: (0)	If they make noise, they'll eventually fail!
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01-14-2016, 08:52 AM	#6
TwinTurboXI Lieutenant Colonel 160 Rep 1,523 Posts Drives: 2011 135i Join Date: Mar 2008 Location: . iTrader: (12)	I'm not fully convinced this is my issue yet, but it certainly could be. Last edited by TwinTurboXI; 10-31-2016 at 02:31 PM..
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01-15-2016, 08:45 AM	#7
RoundelM3 Major General 1837 Rep 6,990 Posts Drives: 15 F80 M3, 22 G01 X3 30i Join Date: Apr 2010 Location: Clayton, NC iTrader: (2) Garage List 2022 BMW X3 [9.83] 2015 BMW M3 [6.50]	If you turn the ventilation fan off and the noise stops, things are pointing to the fan blades or the motor. Mine seemed to do this mostly in cold weather. I don't recall the noise in warm weather driving at all. __________________ 2015 F80 ///M3 Sedan 7DCT Tanzanite, 2022 X3 sDrive30i 8AT Brooklyn Grey
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01-15-2016, 09:02 AM	#8
MightyMouseTech Major General 4338 Rep 6,196 Posts Drives: 13 135i 6MT LeMans Blue MSport Join Date: Feb 2013 Location: Ottawa, Canada iTrader: (0)	And replace it before the blower motor bearing dust gets on the evaporator and corrodes it out.
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