your post screams english. It's like Top gear...but in writing...minus all the english jokes no one in america understands

 

is it like a whistling sound?

 

Supercharger whine.

 

Maybe a vacuum leak?

 

The usual high pitch sound is from the fuel pump. Go stand next to the tank opening and see if what you hear is loudest there.

 

The sound is not of a whistling sound or supercharger. Also I presume if it was a vacuum leak then the sound would appear at engine start, whether cold or hot. The sound only appears when the engine is warm. Netherless I will check for air leaks and the fuel pump as suggested.

Thanks again.

 

I have the same sound after my car sat for 2.5 weeks. Took it to the dealership, they said it was the alternator tensioner pulley and that a bearing needed to be changed but they had to completely redo my setup because they dont make a specific part anymore, quoted $700 in parts, $350 labor. After some research I figured they were talking about changing the alternator tensioner assembly from a mechanical assembly to hydraulic assembly (mechanical assembly are in cars produced until 09/2002; mine is 06/2002). I bought the assembly and installation kit from Autohaus AZ.

INA/OES Accessory Belt Tensioner Assembly; Hydraulic Type; part# 11287838797 ($67.95)
INA/OES Accessory Belt Tensioner Assembly; Installation Kit for Hydraulic Tensioner Update; part #90434001 ($29.95)

Parts arrive next week, planning on DIY, let you know if the noise goes away.

 

Thanks for the info darkcross. Please let me know if the installation kit from Authohaus AZ did the trick.

Btw there is no sign of air leaks under the bonnet and standing next to the fuel tank opening did not give a greater sound. Any other suggests on what the high pitched sound can be? I'm going to try and record a video footage of the car when it makes the high pitched sound and post it up on the thread. Hopefully this would help in identifying the cause of the problem faster.

 

The sounds seems to only appear now after driving for approx 1 hour or 20 miles on the motorway. Any suggestions on what the high pitched noise can be?? Btw could not find any air leaks or sound from the fuel pump.

 

I did the change this weekend and the noise went away. Below are some threads I used for the diy.

Remove Fan (manual cars*)
http://forum.e46fanatics.com/showthread.php?t=439006
*Automatics have a mechanical fan but I cant find the diy I used

Replace Belts
http://forum.e46fanatics.com/showthread.php?t=439006

Change from Mechanical to Hydraulic Tensioner
http://forum.e46fanatics.com/showthread.php?t=410372

It took about 2 hrs only because I didnt have a wrench big enough to remove the 32mm bolt on the mechanical fan. Probably just over an hr of work time.

 

Many thanks Darkcross. But before I go changing the tensioner just a quick confirmation if you have the same symptoms / problems as decribed below.

* The sound appears when the engine is warm usually after dring for an hour or 20+ miles.
* The sound appears to be coming from underbonnet.
* The sound goes away when I press the acclerator/gas pedal.
* The sound appears when stationary/ idle (after engine is warm) and when coasting.
* The sound appears at high and low rev
* The sound is consistent and does not fluctuate


Cheers

 

* The sound appears when the engine is warm usually after dring for an hour or 20+ miles.

Sound appeared a couple of seconds after engine turns on, even on cold start

* The sound appears to be coming from underbonnet.

Yes

* The sound goes away when I press the acclerator/gas pedal.

Yes

* The sound appears when stationary/ idle (after engine is warm) and when coasting.

Yes, but engine did not need to be warm

* The sound appears at high and low rev

Cannot be sure, because of normal engine noise

* The sound is consistent and does not fluctuate

Mine seemed to get louder over time

You can make a visual inspection of the tensioner while the engine is on. My tensioner started to shake slightly, and turning on the AC made the noise louder.

 

I was pretty sure the sound was not coming from the tensioner or pulley, as mentioned earlier I had removed the drive belts and the sound still appeared. So this time round, I decided to take my car to a BMW specialist. They diagnosed the fault as being a leak on the crankcase vent valve. Lucky on this occasion I just had to paid £25 excess on my extended warranty and got the garage to carry out the repair.

Many thanks for everyone's help

 

I have the same whistle sound and my ac vents smell like rotten eggs...it is only when the a/c is on...searched threads...ordered a new cabin filter and will put lysol on the mofo...
The only problem is that on top of all this the ac compressor has this weird clunking sound when it engages....hmmm...
It even turned the engine off ounce when trying to accelerate!!!???? yikes...

Please help...!

 

Help???!!!

 

I wish I could give you some words of advice but i haven't experienced that kind of problem or similar.

 

Ok, I'll be the one to ask the burning question in all the confused american minds........What's a bonnet? The Hood?

With that aside, I've had two "whistling"/high pitch whining sounds since I've owned the car. One was the pulley tensioner (and only really seemed to act up in cold weather) and the other is from the intake. With the stock airbox in no whistle, with the conforti in...whistle. Don't know why, don't care anymore as it's so soft that ya REALLY gotta listen for it. The pulley tensioner on the other hand was LOUD.

 

New compressor...sound is gone...ac is ice cold...!!!

 

Good to know its sorted

 

I think it is the vacum leak.

 

I'm having the exact same symptoms as "thehog" (Fist request). I'm stumped with it now for the past 7 months and can't find the problem. Changed the air-con pump, all the front pulleys, checked the water pump and alternator. What I'm going to do next is to check all the air pipes on the engine etc. Bad BMW.... I'm driving a 318i y2000.