Chasing a whistle / squeal (videos attached)

[Holm]

Squeeling / whistle sound that comes after driving under load for a few minutes.

Noticeably change in sound when letting go or pushing the gas. ( check long video).

If I come to a stop, the car will idle with the sound for everything between 10 second to a minute or two, then it goes away ( I was opening the hood but sound disappeared while i was opening it on one of the vids)

The times i have gotten to open the hood it sounds like its coming from firewall/tb area, but im old and my hearing might be even older

I am planning on attacking it this weekend.

Possible culprits imo

TB gasket and IAC.
Intake manifold
Clutch fan
Pulley
Belt

I have assembled the following rabbit hole parts:

two idler pulleys
Serpentine belt
Intake manifold gasket
Tb gaskets
Spare intake manifold.

Any guesses on whats crying for help?

added a video of fan clutch, hard to spin at first, but spins more and more freely as i keep on truckin’

Videos

 

[Chris]

Let it idle and get a stethoscope in there and listen carefully with it.

If I had to guess it's something to do with the serpentine belt / pulley system. Could be a vacuum leak too but generally that will lead to issues with engine performance / drivability.

 

[macleanflood]

Spray down each pulley in the belt system with water until the noise stops.

And don't forget to check your rear driveshaft. I spent two months chasing a noise I swore was in the front axle. New u joints...needed em anyways... replaced the ring and pinion...down a few teeth... didn't fix it.

Pulled my front shaft...no change
... pulled the rear...bingo...

-Mac

 

[Ctdriver86]

Spray down each pulley in the belt system with water until the noise stops.

And don't forget to check your rear driveshaft. I spent two months chasing a noise I swore was in the front axle. New u joints...needed em anyways... replaced the ring and pinion...down a few teeth... didn't fix it.

Pulled my front shaft...no change
... pulled the rear...bingo...

-Mac

Last vid appears to be at idle…

OP, my bet is pulley/belt stuff. I’ve got a tea kettle whistle sound, noticeable different than yours, from manifold gasket.

 

[Holm]

well, while looking around i heard clickclickclick from the plugs. So started checking them and re torquing thinking i had loose plugs. Turned out one of the plug wires had broke off. Ofc the one closest to the firewall…

So one job became another.


Got the stethoscope out, original sound is not coming from pulleys/belt area. Checked top intake bolts yesterday, going for the lower today

 

[Holm]

Solved! Inner manifold bolt!