Need a diagnosis! Pulleys, belts, or transmission?

[Biggie]

My 2.9L with an A4LD has begun making this noise at around 4000 RPMs, but once I drop below or gain about 500 RPMs the noise goes away. What gives?

https://imgur.com/a/jcSV6pX

Sorry for posting twice in such a short time frame, just trying to get as much information as possible.

 

[rusty ol ranger]

Check the tension on your belts. Thats classic RPM induced belt squeel. If tightening dont help replacing or even a good helping of belt dressing will help

 

[Uncle Gump]

I could be wrong... but it almost sounds like your clutch fan is locked up.

 

[alwaysFlOoReD]

Can you replicate the sound while parked? If so, remove the belt and see if the sound goes away. But I agree with Rusty, that's classic loose belt noise.

 

[Biggie]

I could be wrong... but it almost sounds like your clutch fan is locked up.

What would be the proper fix? Get some WD40 or other lubricant in there and see if it helps?

 

[RonD]

No, a belt squeals because its slipping, so lubing it would opposite of what you want

"Belt dressing" makes is stickier, softens the "rubber" so it grips better

 

[Biggie]

No, a belt squeals because its slipping, so lubing it would opposite of what you want

"Belt dressing" makes is stickier, softens the "rubber" so it grips better

Gump thought it was the Clutch fan, that’s what I was planning on WD40’ing. Putting dressing in a locked up part is definitely a unique strategy though.

 

[RonD]

Fan clutch locked tight would cause belt to slip on water pump pulley, I don't think you can lube the fan clutch externally
With engine off just see if fan can move, if so its not locked tight