Transmission whine?

[MitchT]

The OH's early 2005 E87 BMW 120d (with about 90k miles on it) is making a noise which I believe might be transmission whine.

There's a "whining" noise accompanying the usual engine noise. The pitch of said noise rises with the revs, dropping when the revs drop, such as when you change up a gear. This happens when driving, when the car is stationary in gear with the clutch depressed and stationary out of gear. Basically it can be heard if I increase the revs with the accelerator pedal, whatever the state of the car is otherwise.

Is it transmission whine? Could it be something else, if so, what? What's the cheapest solution to attempt first?

[lufbramatt]

I'd be checking all the belts and tensioners first then acilliaries like alternator etc.

[rallycross]

If you hear it when not moving the it's not gearbox or diff (really common on older 1 series)
More like as said above v belt or clutch release bearing (if sitting not moving push clutch down is the noise there? Now lift clutch does noise go ?)

Normally these are fine well into 120/150k miles ( a slight bit of noise ignore it on an old car).

[MitchT]

rallycross said:

... if sitting not moving push clutch down is the noise there? Now lift clutch does noise go ?

I'll have to give that a try tomorrow. What I did do was ...

1: Sit with the engine running and the car out of gear. Clutch engaged. Noise appeared and rose in pitch when pressing the accelerator to increase the revs.
2: Sit with the car in gear, engine running, clutch depressed. Noise appeared and rose in pitch when pressing the accelerator to increase the revs.

rallycross said:

Normally these are fine well into 120/150k miles ( a slight bit of noise ignore it on an old car).

Main concern is that it appeared recently. I noticed it and knew it was something new, hence the worry, 'cause it's like something's changed.

[InitialDave]

My first instinct would be bearings in some part of the accessory drive, or the alternator etc.

[E-bmw]

^^^^ Wot 'e said.

At least as a first chance.

Try getting a "hand sprayer" on a fine jet with water in it (as accurately as possible so you are only "hitting" one thing at a time) onto every bearing/pulley/belt you can on the engine & see if you can narrow it down.

[MitchT]

rallycross said:

... if sitting not moving push clutch down is the noise there? Now lift clutch does noise go ?

Tried it. Makes no difference. Noise the same with or without the clutch depressed when sat with engine running in neutral.

BUT...

Went out for a drive an hour or so ago and discovered that turning the air con off appears to make the noise stop. I had a play around, turning it off and on and it did appear to stop with the a/c off. Of course, you then find yourself straining to listen and wondering if it's still there or not. Overall the whining seems to be quieter since the weather has cooled and, thinking back, it was after the heatwave started that I first noticed the sound.

Air con related then?

[annodomini2]

[quote=MitchT
Went out for a drive an hour or so ago and discovered that turning the air con off appears to make the noise stop. I had a play around, turning it off and on and it did appear to stop with the a/c off. Of course, you then find yourself straining to listen and wondering if it's still there or not. Overall the whining seems to be quieter since the weather has cooled and, thinking back, it was after the heatwave started that I first noticed the sound.

Air con related then?
[/quote]

Either the Aircon clutch or belt is slipping when engage or the compressor bearings are screwed.