Buzz from Alternator

The Bavarian · 05-23-2015, 03:25 PM

About an hour after a nice driver in the hills West of Denver, I popped the hood to continue my discovery of the new car. While looking around, I heard an odd noise. If you've ever played with a DC motor and throttled the rheostat just enough to get the motor to buzz, but not turn... this is the sound. I traced the sound to the general area of the alternator.

I inspected a few of the wires on the alternator but everything felt tight.
I tried locking and unlocking the car thinking that perhaps something was spooling up and preparing for start... but no change. I tried to turn the spindle just a little to see if moving the alternator might affect it, but again no change.

At some point it stopped buzzing and then came back for about 30 seconds and then went away?

I'll go out a few times over the weekend and see if I hear the same thing.

Any ideas. Certainly the alternator shouldn't have voltage running through it with the ignition off... Unless I've got an issue with wiring - correct?

Douche · 05-23-2015, 07:12 PM

Are you referring to the water pump?

csu87 · 05-23-2015, 07:17 PM

sounds like you may have an electrical short. Do you have any meters you can test with?

The Bavarian · 05-23-2015, 08:19 PM

I have about three sets of multimeters. I'd just need some help with where and what I am testing for. Ground, impedance, voltage, amperage?

I had it in the garage this afternoon and could not duplicate the sound.

To be clear about the situation this morning. The "key" was not in the "ignition" so the radio, etc was not on. All I did was unlock the car, open the door, pop the hood and take a listen.

I've never owned a car with an electric water pump? But I'm making a lot of firsts with this car. I would assume that the water pump would not come on unless I had the ignition on.. (key in the holder dude...) Sorry I own an 88 SAAB 900 Turbo and a '98 Land Cruiser - I'm way behind the times.

csu87 · 05-23-2015, 08:44 PM

take a picture of what is making noise?

chrisbimmer12 · 05-23-2015, 08:50 PM

The alternator can have voltage from the battery running through the charging system while the ignition is off. Have you heard that sound before? is your 335 turning on or not?

The Bavarian · 05-23-2015, 09:11 PM

The car starts up fine. This is the first time I've heard the noise and just thought it was odd. Nothing I've heard with any other car. As a new car to me, I'm probably being a little over cautious about things I find.

05-23-2015, 03:25 PM	#1
The Bavarian Private 5 Rep 67 Posts Drives: 2011 335i e90 M-Sport, AT, PPK Join Date: May 2015 Location: Denver, CO iTrader: (0)	Buzz from Alternator - Car not running. About an hour after a nice driver in the hills West of Denver, I popped the hood to continue my discovery of the new car. While looking around, I heard an odd noise. If you've ever played with a DC motor and throttled the rheostat just enough to get the motor to buzz, but not turn... this is the sound. I traced the sound to the general area of the alternator. I inspected a few of the wires on the alternator but everything felt tight. I tried locking and unlocking the car thinking that perhaps something was spooling up and preparing for start... but no change. I tried to turn the spindle just a little to see if moving the alternator might affect it, but again no change. At some point it stopped buzzing and then came back for about 30 seconds and then went away? I'll go out a few times over the weekend and see if I hear the same thing. Any ideas. Certainly the alternator shouldn't have voltage running through it with the ignition off... Unless I've got an issue with wiring - correct?
	Appreciate 0 Tweet Quote

05-23-2015, 07:12 PM	#2
Douche Banned 466 Rep 1,980 Posts Drives: Car Join Date: Jan 2015 Location: Location iTrader: (0)	Are you referring to the water pump?
	Appreciate 0 Quote

05-23-2015, 07:17 PM	#3
csu87 Banned 2134 Rep 3,554 Posts Drives: 09 335xi Join Date: Nov 2013 Location: Northern Colorado iTrader: (0)	sounds like you may have an electrical short. Do you have any meters you can test with?
	Appreciate 0 Quote

05-23-2015, 08:19 PM	#4
The Bavarian Private 5 Rep 67 Posts Drives: 2011 335i e90 M-Sport, AT, PPK Join Date: May 2015 Location: Denver, CO iTrader: (0)	I have about three sets of multimeters. I'd just need some help with where and what I am testing for. Ground, impedance, voltage, amperage? I had it in the garage this afternoon and could not duplicate the sound. To be clear about the situation this morning. The "key" was not in the "ignition" so the radio, etc was not on. All I did was unlock the car, open the door, pop the hood and take a listen. I've never owned a car with an electric water pump? But I'm making a lot of firsts with this car. I would assume that the water pump would not come on unless I had the ignition on.. (key in the holder dude...) Sorry I own an 88 SAAB 900 Turbo and a '98 Land Cruiser - I'm way behind the times.
	Appreciate 0 Quote

05-23-2015, 08:44 PM	#5
csu87 Banned 2134 Rep 3,554 Posts Drives: 09 335xi Join Date: Nov 2013 Location: Northern Colorado iTrader: (0)	take a picture of what is making noise?
	Appreciate 0 Quote

05-23-2015, 08:50 PM	#6
chrisbimmer12 New Member 4 Rep 10 Posts Drives: 2012 BMW 328i Join Date: May 2015 Location: Manhattan, NY iTrader: (0)	The alternator can have voltage from the battery running through the charging system while the ignition is off. Have you heard that sound before? is your 335 turning on or not?
	Appreciate 0 Quote

05-23-2015, 09:11 PM	#7
The Bavarian Private 5 Rep 67 Posts Drives: 2011 335i e90 M-Sport, AT, PPK Join Date: May 2015 Location: Denver, CO iTrader: (0)	The car starts up fine. This is the first time I've heard the noise and just thought it was odd. Nothing I've heard with any other car. As a new car to me, I'm probably being a little over cautious about things I find.
	Appreciate 0 Quote