[335xi]

As I've posted before, the car emits an oscillating humming noise when the fan/heat is on. When i turn the fan/heat off the noise stops. My friend's 2006 does not exhibit this noise. I just talked to my SA and he says it's normal, that it's the electric water pump. Does that make any sense to you guys?

 

[DaveCM5]

My car seems perfectly quiet inside to me, but everyones perception is different. Can you record the humming sound and post it?

On another note, I had a horn replaced a few weeks ago and when I got the car back the engine was making a buzzing noise that would increase with engine RPM. I turned around and brought it back and had them listen. Of course they couldn't hear it, but I could. They then said they might hear it, but it was a normal noise. I insisted it began after they installed the horn. Finally after about 20 minutes of arguing, they agreed to put the car back on the lift and check the horn even though the insisted there was no way the horn install could have caused the noise. Turned out the technician had ordered the wrong horn and "tried to make it work", and it didn't fit right and was vibrating against something else which produced the buzzing noise. Once they took it out the buzzing stopped, and a week later when the correct horn went in everything was fine.

My point is I think the dealer hates chasing down "noises" because it can come from anywhere, and some noises are normal. But if you insist enough, with a good service advisor, he should at least look for a cause.

Good luck.

 

[335xi]

Well, you are in Florida, probably never gets cold enough for that pump to run

My car seems perfectly quiet inside to me, but everyones perception is different. Can you record the humming sound and post it?

On another note, I had a horn replaced a few weeks ago and when I got the car back the engine was making a buzzing noise that would increase with engine RPM. I turned around and brought it back and had them listen. Of course they couldn't hear it, but I could. They then said they might hear it, but it was a normal noise. I insisted it began after they installed the horn. Finally after about 20 minutes of arguing, they agreed to put the car back on the lift and check the horn even though the insisted there was no way the horn install could have caused the noise. Turned out the technician had ordered the wrong horn and "tried to make it work", and it didn't fit right and was vibrating against something else which produced the buzzing noise. Once they took it out the buzzing stopped, and a week later when the correct horn went in everything was fine.

My point is I think the dealer hates chasing down "noises" because it can come from anywhere, and some noises are normal. But if you insist enough, with a good service advisor, he should at least look for a cause.

Good luck.

Basically when it's cold outside, this pump fires up before the regular mechanical pump because the regular pump is controlled by the thermostat which doesn't open right away when it's really cold outside. That sounds like a perfectly normal explanation except for the fact that when it's really cold I hear the noise even after 20 minutes of driving. As far as recording it goes, it's hard to discern the noise in a recording since it mixes in with the motor noise. I will try but I doubt it will work.

 

[DaveCM5]

Well, I may not be the one who can offer help because I live in Florida and keep my car in a garage, so it never gets extremely cold. But it's been out in weather in the 40's in my work parking lot during the day and when I turned it on I did not hear an extra pump noise or anything.

Good luck with it. I wonder if you could try test driving a 2008+ 550i or 535i if you can't find another 2008+ model M5 around? I would think that other 5-series cars would have a similar setup if it's not a pump on the engine or drivetrain, but that's just a guess.

 

[335xi]

Dave, thanks, I appreciate the attempt to help

Well, I may not be the one who can offer help because I live in Florida and keep my car in a garage, so it never gets extremely cold. But it's been out in weather in the 40's in my work parking lot during the day and when I turned it on I did not hear an extra pump noise or anything.

Good luck with it. I wonder if you could try test driving a 2008+ 550i or 535i if you can't find another 2008+ model M5 around? I would think that other 5-series cars would have a similar setup if it's not a pump on the engine or drivetrain, but that's just a guess.

A friend of mine just bought (today) an 08 535i so I will check with him when the car is delivered.

 

[335xi]

Update, the 2008 535i doesn't hum like my 2008 M5

Anyone with 2008 M5 in the northern parts of the world where it's still cold care to comment whether they can hear a hum when the car is 1st started when the temps are below 50 degrees Fahrenheit? The hum goes away if I turn off the heater completely.

Thanks

 

[arich]

In NY and the car stays outside during the day. There is no different noise when it's cold compared to when it comes out of the heated garage.

 

[M5_BJ]

I have the same experience as you 335xi, I haven't got a chance to bring in to the dealer to check.
But mine does the same thing.

 

[335xi]

Well, if we get a bunch of us having the same thing then it may be 'normal'

I have the same experience as you 335xi, I haven't got a chance to bring in to the dealer to check.
But mine does the same thing.

Right?