L67 whistling noise

[Schlotzky]

My L67 has a whistling noise I have been trying to track down. It's apparent mostly in stop and go traffic at low RPM. I thought it was the alternator, so I purchased a rebuild kit and replaced the bearings and brushes. I also replaced all four idler pulleys with bearings. The whistling seem unaffected. I had tried locating it with a stethoscope (well a garden hose anyway) buy I've been unable to locate the exact source. It does seem to be coming from the front of the engine, and it doesn't seem to be coming from the supercharger.
The car just passed 70K.

Here is a video:

[J Wikoff]

Try running without the belt for a minute and see if it goes away. And look for the vacuum line that runs under the nose of the supercharger.

[Schlotzky]

I'll check for that vacuum hose. The reason I haven't pulled a belt yet is because of the tremendous work that entails that I just went through a couple months ago. I'll see if I can remove the supercharger belt and get it out of the way enough without removing it to prevent a snag and start it up. Thanked for the reply!

[Schlotzky]

I found a very small vacuum line going to the engine under the snout and inspected it and it checks out. I also disconnected the Supercharger belt and ran the engine and the noise was unaffected. I kind of think it's the alternator, but don't understand why replacing the bearings didn't quiet it unless the internal fan is making the noise somehow. The blades didn't appear bent or in any way damaged when I rebuilt it. Its still hard even with a length of hose to pinpoint the source exactly. I was hoping someone on here had run into this before.

[buickman104]

I had the same symptoms. It turned out to be a IAC that failed.

[Schlotzky]

Interesting. Maybe I'll try running the engine without the other belt and see if it still whistles. That would help isolate it if it were the IAC.