Whistling sound in cold temps

[DK327]

I've had this issue for a couple of years now and it seems to be getting worse. I noticed it after timing belt and water pump were replaced which might be a coincidence and not related.

When the ambient temp is below ~35F I start getting a whistling sound coming from under the hood when revving the engine at certain RPM range, usually around the 2K mark. I'm linking to a video, hoping someone can point me in the right direction.

Also at cold temps, one of my pulleys or the alternator bearing is making a squeaking sound, so this might also be related. The original OEM alternator was replaced with a "high output" one back in 2017 and is still in good condition.

Thanks in advance!

2000 T4R Whistling Sound Under the Hood - YouTube

 

[FD7683]

To knock out timing belt noise, pull off all 3 belts from the serpentine belt system and run the engine for just a short time and try to hear the noise from the engine. Not good news if the timing belt pulleys are making noise.

 

[spartacus]

A cracked vacuum hose, Also bad o2 sensor gasket or a pinhole in the exhaust can cause a whistling noise.

 

[gamefreakgc]

Wow, that's really loud. I had read this as I have what I believe to be an intake whistle around the same temperature range that goes away but yours isn't just a whistle, that's a downright scream!

I had an upper plenum/intake gasket get loose and make that noise once. It could be that simple as to just tighten down the plenum. I realize you cannot access the lower plenum bolts without removing the upper entirely though.

 

[Auce]

Same here but when the engine warms up the noise goes away.