NEWBIE with X5 e70 3.0d possible tranny problems and timing chain advice

[shak]

Hi, 
I've recently bought a 57 plate BMW X5 3.0d (single turbo) with 97,000 on the clock.  Its easily the best car I've ever owned and I hope its gives me years of hassle free driving!  I'm new to Diesels and have never owned an automatic car so am not sure if I am being paranoid or overly cautious here, as i have a few questions that perhaps someone on here could answer. 
Here goes...
Transmission/gears whining noise: When driving there is a whining noise which seems to be related to the gear/transmission...It only makes the noise whilst the car is moving, and seems to do it at all times (when I put my foot down, and when I am not on the gas either, when I am in full auto, or sport mode - doesn't make a difference, the noise is there).  Its not too loud (I think passengers will assume its normal engine noise till I point it out), but I noticed it.  Is this normal for the X5?

Timing chain: After reading reports on the net about timing chain issues I had a brief chat with an indy BMW specialist about whether I should have the timing chain changed as a precaution.  He reckoned it wasn't worth changing the timing chain willy nilly as it costs £500 and these engines arent known for the chains failing.  Since the conversation I have noticed some form of noise which sounds like a chain/belt running loosely (its very hard to describe this in words i guess!).  It seems to be coming from the front portion of the engine, but I cant be sure.  To put my mind at ease I'm going to have it checked out with another BMW specialist and see what they say (especially as they may be able to hear the noise themselves with the car present).
Assuming they say its wise to change it, is £500 a reasonable price or can it be done cheaper?

Auto box changing gears higher in the rev range when I've been sat in traffic: Normally the car changes gears at 1700-2000 rpm in normal conditions, but i've noticed the box changes gears at about 3000rpm when I've been sat in relatively heavy traffic and the engine is fully warm.  If I switch off the engine and switch on again and resume driving, I think it goes away (but I'm not 100% sure on this). Is this normal, or indicative of some fault/issue? 

If it gives me no issues I intend to keep the car for a few years at least.  Are there any recommendations for things I can have done to ensure it stays in reliable condition (as I can't be sure how well previous owners have maintained it)
Transmission fluid change: I've read its recommended to have the transmission fluid changed on the car (even though its sealed for life).  Any ideas how much this will cost, and is it worth doing?

I'll take the car to an indy specialist to have it checked out on some of the above issues but would be grateful for any responses/suggestions as I know there will be a wealth of experience on here.

Sorry for the long post!

[TomX5]

Are you sure that the whining noise that you are hearing isn't the whistling sound of the turbo?

As for the timing chain noise...I'm not sure about this one. The sound of my engine changes when I switch the aircon on (the noise of the compressor running). Could this be what you are hearing?

[X5Sport]

What tyres are fitted?  What is the tread depth variation front/rear?  If more than 3mm difference the whine could be either a diff or transfer box complaining.  Ignore it at your peril as the transmission may break!  These cars are very intolerant of wide tread depth variance and type of tyres fitted.  Always best to change as a set of 4.  Tyres specific to BMW are all marked with a '*' on the sidewall and should be RFT (you can change to non-RFT though).

Gear changes can be affected by temp, especially if the gearbox oil cools down.  The change points vary with temperature and you may notice that when it is cold it will use 1st more and need to be going faster before 6th engages until warmed up.  Similarly a very warm box may have shifted points.  If worried get a ZF specialist who can read any error codes stored to have a look at it.

[Riggie]

I have a low whining noise on mine which is engine speed related. Initially it sounded like belt noise, but just to check, I took the plastic cap off the serpentine belt tensioner and sprayed some WD40 into the bearing and that seemed to quieten it for a short time. There is also an idler which could cause the noise if the bearing if worn. Also consider alternator bearing?

Sorry, just re-read your post and you say its only when the car is moving, ignore my last !

[shak]

Thanks a lot for the responses. 
I took the car to a local indy this morning without an appointment.  He listened to the engine on warm tickover and got me to rev the car a few times.  He said there was a slight noise but it wasn't likely to be the timing chain as my engine (M57) isn't known for timing chain failure.  He said it could be related to the alternator (can't quite remember exactly what though).  but he gave me the impression I didn't have much to worry about there. 
As he was busy he didn't have a chance for a test drive to listen to the engine/transmission whining. Will need to book in for a proper check...
RIGGIE - as far as I can hear, I think the noise/whine is engine speed related too, as it goes up in pitch with speed. 
X5SPORT - I have Bridgestone Duelers Run Flats Stars- a staggered set-up.  I think all four tyres have equal amount of tread depth - they were fitted virtually new by the person I bought the car from, just before he sold it to me.
TOMX5 - I know what you mean about the Air Con, but that is usually a quieter sound.    Its definitely a whining noise, rather than turbo whistle.  As far as I have heard, the noise hasn't varied when the AC is on or off. 

[X5Sport]

Sounds like the tyres aren't a potential cause then... 

And no the M57 is not known for chain issues, unlike the V8 of old.

Any indication of which end of the car the transmission noise is coming from?  You have a rear diff, front diff and centrally mounted transfer box on the back of the gearbox.  Does it get worse going around corners, uphill or downhill under load?

kkx5 is our resident transmission specialist.  Try pinging him a PM?

[shak]

Sorry to drag up an old post but thought id let people know what the noise was: It appears its just a slightly noisy alternator and nothing to be concerned about. I'm assuming its one of the bearings.
Well I'm glad it ain't the transmission parts!

[Turks]

Always good to bring a thread to a close with a conclusion. Helps anyone else who is suffering from similar issues or concerns.

I would have said Alternator too, and expected it to be slightly more obvious when AC was on... if you switch off the noise can get quieter after a few seconds.


Turks.