2007 328XI loud whistle HELP!!!!

[Sn0x489]

My 2007 328XI has a loud squeal/whistle coming from somewhere upfront under the hood. If I turn the car off and then back on the sound is gone, when I hit the gas it goes away some, I'm not 100% but it seems if I keep my a/c off the sound doesn't happen. Also i don't know if it is related to this or not but driving down the high way my car like surges/dies quick and the yellow car on a lift light comes on and the car runs fine afterwards.

[ELVA164]

Maybe someone installed one of these?

[Sn0x489]

No

[TonyAngel]

Without having the car in front of me, I can't tell for sure, but it sounds to me like you have a belt/pulley issue, possibly with the A/C. As for the light, it may or not be related, but since it is triggering a light, getting the car scanned for codes with a BMW specific scan tool will take a lot of the guess work out it.

[ptarditi]

Open the hood, then start the car, look at your serpentine belt and if it seems to be skipping or stuttering, that's the start of your diag, its common onthat motor for the tensioner to go bad, its also less common on that motor for the A/c compressor to fail. If you're looking at the belt and all seems normal then a whistling noise could be coming from the PCV system which is built into the valve cover, that could also lead to a check engine light and rough running.

[White94RX]

I'm thinking the valve cover is bad, causing air to be sucked in from either the front or rear crank seal. I've seen it plenty of times.

[jclausen]

With the engine running and the noise is happening slowly loosen the oil cap on the valve cover if it goes away I would belive it would be in the pcv valve built into the valve cover

[MauiM3Mania]

Moved from General BMW sub-forum.

[SlackTube]

I 3rd the crankcase vent valve

[Pilgrim]

Whistles are usually vacuum leaks. Shrill or high pitched noises are usually accessory bearings or belts.