Diagnosis of squeal

[Billdaman1]

Diagnosis of squeal- frustration! Replaced serpentine belt, tensioner, idler. Still squeal. (No need to flame me on throwing parts at it…the sound is a slam dunk serpentine belt squeal)
Trusted Mechanic perplexed. Could‘nt find, thought it may be exhaust, which he doesn’t do. Muffler shop says not exhaust related.

Brought back to mechanics, they said they removed the serpentine belt and ran it but didn’t find source.

I have chassis ears ordered, should be here tomorrow. The truck must be moving to make the noise, so under hood diagnostics not possible without chassis ears . Definately coming from passenger side underhood.

Frustrating. Anyone had this serpentine or idler pulley type noise, but it isn’t type issue?

www.facebook.com/bill.daws.752/videos/219920113903948/?idorvanity=781634888673442&notif_id=1678549038086091&notif_t=video_processed&ref=notif

 

[Blckshdw]

Video link isn't working, says it's no longer available

 

[Billdaman1]

Video link isn't working, says it's no longer available

https://www.facebook.com/video.php?v=219920113903948

 

[Billdaman1]

www.facebook.com/100006464124623/videos/219920113903948/

 

[mrrsm]

(1) In order to ensure that the Accessories-Serpentine Drive Train IS the Culprit. Remove the Belt, Start the Vehicle and LISTEN for the expected Noise. If it is STILL Present afterwards...then the Serpentine Belt and Pulleys, etc. are NOT the Problem.

(2) If the Water Pump Bearings are SHOT... with the WP being coupled to the Caged Radiator Fan, it can Wobble and Tilt In and Out very dramatically along its Outside Diameter (Counter-Clockwise to the Direction of Engine Rotation).

As this occurs, the Serpentine Belt tries to move in a straight line driven from the Crankshaft Harmonic Balancer on the Grooved Side while moving the WP using the SMOOTH Side of the Belt.

As the WP *Wobbles* around on the Bad Bearings, the Hollow, Smooth WP Pulley mounted to the WP with the 4 Bolts will ...Amplify the *Chirps... as the Serpentine Belt tries moving around in a Straight Line, BUT... Grabbing & Slipping along the Smooth Outer Surface of WP Pulley at High Frequency can create a horrendous noise.

(3) The Alternator can also get involved with squealing from having a Bad Outer Bearing.

 

[Mooseman]

Another possibility is pulley alignment.

Unfortunately that particular tool is expensive at $274USD

https://www.amazon.com/dp/B004SF0TLI/?tag=gmtnation-20

Also check to confirm if it's a misalignment or a loose belt.

It's possible you may have the wrong belt, especially if you have an EXT/XL/XUV. I had that problem on my EXT and recently with my 07 that I replaced the pump with one from my EXT in that the belt was too long. I went to the next shorter belt and the problem was solved.

 

[Billdaman1]

Another possibility is pulley alignment.

Unfortunately that particular tool is expensive at $274USD

https://www.amazon.com/dp/B004SF0TLI/?tag=gmtnation-20

Also check to confirm if it's a misalignment or a loose belt.

It's possible you may have the wrong belt, especially if you have an EXT/XL/XUV. I had that problem on my EXT and recently with my 07 that I replaced the pump with one from my EXT in that the belt was too long. I went to the next shorter belt and the problem was solved.

Thanks Mooseman, so I’m pretty sure it’s not a loose belt. When I replaced the belt and tensioner belt went on easy. When I replaced the idler pulley, needed a crowbar to get the belt back on. Just a few mm difference in diameter tightened it up to the extreme!

 

[mrrsm]

Check out Post #20 in THIS Thread for a Technical Explanation of why that might lead to problems:

Can a 5 mm shorter serpentine belt cause problems?

When working on my thermostat I noticed that the belt that's on is a 6PK2320. As far as I know it should be 2325 (mm). Can this cause problems, like engine squealing at high revs, mostly when cold? (I know this can be a pulley but when I had the belt off I tried to spin all the pulleys and none...

gmtnation.com

 

[Mooseman]

If you look at your tensioner, there are marks on the two portions, like a triangles or arrow, that show where it should be sitting for proper tension. Mine was way below until I got the shorter belt and now sits perfectly in between the marks.

This pic from the internet but depicts what it looks like.