Help Diagnosing a subtle hum while driving

///Mik3 · 03-09-2015, 09:41 AM

So I've recently noticed a constant hum sound in my totally stock 2009 328i Wagon (60k miles) that I don't think is normal, but I can't think of what it could be. Here are a couple observations i've made:

- Noticable starting at about 40mph but most noticable at 70-75mph
- It's kind of a medium pitch hum that increases in pitch as the speed increases
- It is NOT affected by RPM
- Kinda seems to be coming from the rear of the car, but kind of hard to tell as it's kind of a dull sound
- I've rolled down the windows to see if it becomes louder or more noticable and it doesn't

any ideas? Considering it is affected by speed and not RPM i'm kinda wondering if it's somewhere related to wheels/tires or brakes? I know wheel bearings make a noise when they're going bad, but i've never heard what that sounds like, could it be that? Any help would be great. Thanks!

Welcome to NBA Jam · 03-09-2015, 09:52 AM

Wheel bearings can make a low hum like that when they are going bad. Tires can also make a hum like that when they're wearing unevenly, out of balance, or getting to the end of their life. 60k miles is very early for a wheel bearing to go out, so I would first start by balancing the wheels if you haven't done that in a while, then checking the wear pattern of your rear tires before moving on to checking the wheel bearings.

jskin1510 · 03-09-2015, 01:18 PM

I notice this on my car the other day most like at speeds around 55-70mph, It's very faint but if you are listening for it noticeable. If it's the same as mine I'm thinking it's tire noise. maybe they are wearing uneven, maybe not. My e46 does this also but its definitely louder on that... two brand new tires in the rear and a staggered set up. Car drives great as well so I'm not too worried about it.

///Mik3 · 03-10-2015, 09:54 AM

Quote:

Originally Posted by jskin1510

I notice this on my car the other day most like at speeds around 55-70mph, It's very faint but if you are listening for it noticeable. If it's the same as mine I'm thinking it's tire noise. maybe they are wearing uneven, maybe not. My e46 does this also but its definitely louder on that... two brand new tires in the rear and a staggered set up. Car drives great as well so I'm not too worried about it.

yeah, the car seems to be running normal. Hopefully it's nothing serious?

03-09-2015, 09:41 AM	#1
///Mik3 gonna miss the M, but the wagon is sweet! 120 Rep 628 Posts Drives: 2009 328i Wagon Join Date: Jan 2010 Location: CA iTrader: (1) Garage List 2009 328i Sports Wagon [10.00]	Help Diagnosing a subtle hum while driving So I've recently noticed a constant hum sound in my totally stock 2009 328i Wagon (60k miles) that I don't think is normal, but I can't think of what it could be. Here are a couple observations i've made: - Noticable starting at about 40mph but most noticable at 70-75mph - It's kind of a medium pitch hum that increases in pitch as the speed increases - It is NOT affected by RPM - Kinda seems to be coming from the rear of the car, but kind of hard to tell as it's kind of a dull sound - I've rolled down the windows to see if it becomes louder or more noticable and it doesn't any ideas? Considering it is affected by speed and not RPM i'm kinda wondering if it's somewhere related to wheels/tires or brakes? I know wheel bearings make a noise when they're going bad, but i've never heard what that sounds like, could it be that? Any help would be great. Thanks! __________________
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03-09-2015, 09:52 AM	#2
Welcome to NBA Jam Is it the shoes!? 3884 Rep 5,112 Posts Drives: (Sold) 2011 E92 335i ZMP 6MT Join Date: Mar 2014 Location: USA iTrader: (1)	Wheel bearings can make a low hum like that when they are going bad. Tires can also make a hum like that when they're wearing unevenly, out of balance, or getting to the end of their life. 60k miles is very early for a wheel bearing to go out, so I would first start by balancing the wheels if you haven't done that in a while, then checking the wear pattern of your rear tires before moving on to checking the wheel bearings.
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03-09-2015, 01:18 PM	#3
jskin1510 Second Lieutenant 28 Rep 265 Posts Drives: 08 BMW 335xi Join Date: Feb 2015 Location: Maryland iTrader: (2)	I notice this on my car the other day most like at speeds around 55-70mph, It's very faint but if you are listening for it noticeable. If it's the same as mine I'm thinking it's tire noise. maybe they are wearing uneven, maybe not. My e46 does this also but its definitely louder on that... two brand new tires in the rear and a staggered set up. Car drives great as well so I'm not too worried about it. __________________ 08 335xi- CP-E DCI's,VRSF 7" FMIC, UR Charge pipe w/ Tial Q BOV, JB4 G5, PE mod, 19" Sonic Tuning SC 7 wheels
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