Need help identifying screeching sound from hell

Westtown Willy

TJ dummy
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May 10, 2018
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Clown World
cranked up the TJ yesterday morning & this horrendous high pitched whistling sound started, not sure what it is. My first thought was the belt and/or something related to the bitter cold (it was around 20 degrees), but I ran it for around 45 minutes & it didn't stop. At first it stopped with increased RPMs but came back at idle, then it went up & down with the RPMs & stopped at idle, then it did it non-stop.

Today after work I cranked it up again, much warmer out at around 50. Still made the same sound but not as loud or high pitched, & after around 10 minutes it went away. I thought maybe a vacuum leak or something but couldn't pinpoint the source just walking around listening, & with my stethoscope it seemed to be clearest through the coil pack.

Anyway I managed to capture some of it, any help identifying the sound would be appreciated:

 
Could also be the idler pulley, tension pulley, etc.
Spray some water on them one at a time till noise goes away.

This is where I’d start. Idle, if it’s screeching, then use a water bottle and spray your belt. If it stops for a few seconds, you know where to start hunting.

I’d look at idler pulley etc, but I’d also look and see if the Harmonic Balancer is separating and that pulley is getting out of whack. I had to replace mine.
 
X
Sounds like a bearing screaming to me. Alternator and AC compressor working fine? If you have a 2005 or 2006 check the OPDA.

X 2 on the OPDA. ThTs what mine was. It sounded like a screeching fan belt. Put your fingers on the OPDA when the noise is happening. If that’s the problem you will feel the vibration in your fingertips.
 
He has an 04, not your bad OPDA years

correct, and I replaced my camshaft position sensor a few years ago when it went wonky on me, I took a good listen to that & it sounded normal.

I haven't had a chance to try some of the other suggestions above yet, just collecting ideas & one night this week or maybe the weekend I'll try and nail it down.

In the short clip I posted it sounds distinctly like a belt issue but when it did it over the weekend it was markedly louder & high pitched - very much not belt-sounding, sounded more like a steam whistle.
 
I like to use an automotive stethoscope to track down sounds like that. It's also a fairly inexpensive tool to keep around.
 
correct, and I replaced my camshaft position sensor a few years ago when it went wonky on me, I took a good listen to that & it sounded normal.

I haven't had a chance to try some of the other suggestions above yet, just collecting ideas & one night this week or maybe the weekend I'll try and nail it down.

In the short clip I posted it sounds distinctly like a belt issue but when it did it over the weekend it was markedly louder & high pitched - very much not belt-sounding, sounded more like a steam whistle.

Definitely water bottle it, you'll find out quickly if it's the belt. If you squirt and no change, I'd look for a pulley bearing etc.
 
Pop the belt off and check it. Might be a crank damper as well.
 
I like to use an automotive stethoscope to track down sounds like that. It's also a fairly inexpensive tool to keep around.

I agree, as I said in the original post it sounded like it was loudest through the coil pack which made no sense

Could also be the idler pulley, tension pulley, etc.
Spray some water on them one at a time till noise goes away.

Definitely water bottle it, you'll find out quickly if it's the belt. If you squirt and no change, I'd look for a pulley bearing etc.

so the water didn't work but I pulled the stethoscope out again & the idler pulley was screaming so I'm pretty sure that's it. Once I did that I could hear it more distinctly without the stethoscope, definitely sounded louder the closer I got to it.

This was like trying to find a cricket in the house

I'll grab a new pulley & pop that in, see what's what then...

Thanks all, I'll of course report back if this does the trick!
 
Could also be the idler pulley

Winner Winner Chicken Dinner!

My thanks, and gratitude; somehow you nailed that from a crappy 12 second video clip while I had my actual head in the engine bay for a half an hour & couldn't figure it out :LOL:

$14 & about 5 minutes of work & she's quiet as a church mouse:

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Just saw this, but I had the same problem last winter with the same sound and it was my idler also