BMW Z4 high pitched squealing at cruise?

[Speeddog]

Pretty sure it's an '04, with the automatic.

High pitch squeal when at cruising throttle, not rpm or speed related.
It's not real loud, but supremely annoying.

Turning AC on or off makes no difference.
Trans in full-auto or "manual" makes no difference.

Car went in for a general inspection (as it's new-used), tech said maybe it's a valve. 

Wondering if anyone has experienced this or heard of it.

Link to a good BMW forum?

[Howie]

If the noise is from the engine, you might try going to a shop that has a smoke machine.  I've seen minor vacuum leaks do that, though I would expect an '04 to throw a lean trim code.  I assume you can't make the car squeal when not in motion?  If you can get the car on a dyno you may be able to locate the noise.

[Porsche Monkey]

I would take it to a BMW dealer because they have most likely seen that issue before. I have had belt pulleys make noises before, I've had exhausts making squeeling noises before, ect. Can it be duplicated when not moving?

[Popeye the Sailor]

Try leaving the wife at home 

[Speeddog]

Try leaving the wife at home 

That's cold.   




I don't think the car is throwing a code.
No dash lights on that shouldn't be, at least in the 2 hrs or so I've been in the car.

Seems to be an air leak that's very specific to a narrow range of vacuum.
I can get the engine briefly into that range with a free rev, but it requires a load to keep it there for any period of time.
It's very high frequency, higher than a mosquito.

And, No, I'm not going to work the trans against the brakes in the driveway to debug it.

I've no idea how fond BMW is of vacuum powered stuff, for all I know it could have 30 feet of vacuum hose in the car.
Or maybe nothing is vacuum powered except the brakes.

[caperix]

Is it a 3.0 or 2.5?  The 3.0 models have a tube running from the intake to the cabin to increase intake noise heard by the driver.  This can cause some strange things to be heard in the cabin.
The only common sqeels on that engine are belt tensioners, they tend to be worse when at cold idle though.
Try playing with the radio also, alternators can produce buzzing noises through the speakers when they are failing.  If all else fails you can always just turn the radio up until the noise goes away 

[mstevens]

My 3.0 has never done that, but mine's a manual. I blame your automatic!

[somegirl]

If all else fails you can always just turn the radio up until the noise goes away 

The Tom & Ray solution!

[Speeddog]

Gotta get to the car and have the hood up, see if there's any possible suspects hiding in there.

Thanks to all for the suggestions.

I don't think I can upsell the 'turn the radio up' option as a solution. 

It could be some sort of electronic noise I suppose. 

It's such a high frequency that it's very hard to isolate location in the cab.

[somegirl]

It's such a high frequency that it's very hard to isolate location in the cab.

Kids hear high frequencies better...any around that you can recruit?

[red baron]

Kids hear high frequencies better...any around that you can recruit?

Ooooo, dog she's callin you old.

[Speeddog]

Ooooo, dog she's callin you old.

I still think of kids as ten years old. 

Hadn't thought of recruiting child labor, but that's an interesting suggestion. 

[corey]

it's not a body whistle is it? the mirrors on my ladies mini whistle terribly at cruising speeds...

[sno_duc]

Try this link.
http://www.bimmerfest.com/forums/forumdisplay.php?s=&daysprune=-1&f=7

[Gus Duc]

Head west on Hueneme road about 2 miles....... you'll find BMW's import & tech facility........ they can fix it

p.s.  We just rode or bicycles home from Mandalay Beach & I was thinking of you guys as we passed....... 75 miles on a tandem with a 9 year old stoker............ good times