Background:
2000 GMC Silverado extcb 4x4 5.3l 120,000km

Problem:
I have had a major (super loud) howl/squeal coming from the belt area of my truck. It happens at idle and varies with throttle position. It used to only happen when it was cold back in November and then go away as the truck warmed up but now it is persistent every time I start it and doesn't go away. I don't know if it is "cold" dependent or if the problem has just finally come to a head as we haven't had a day over -10 for quite sometime for me to check to see if the sound goes away once it warms up.

Attempted fixes:
I started it one cold morning and let it howl. I oulled off the splash gaurd and proceded to hit all the pulley bearings I could see with kroil to see if I could find the problem bearing or pulley. No dice, it didnt stop.

Its impossible to tell where the sound is coming from with the naked ear with all the noise of a running motor. I havent taken the belt off and run the truck for a bit to see if if that stops the noise.

Side note:
The alternator went south on me about a month ago so I replaced it and the battery and belt. I figured I might as well when I was under the hood anyways. All is well with the charging system now, so I think this should eliminate the alternator and the belt from the equation.


Any ideas???

I'm going to get a mechanics stethoscope and try to pinpoint the problem. What should I be listening for and where should I be listening with the probe of the stethoscope????

Waterpump/pulletys/AC pulleys etc...???

 

Probably the belt tensioner bearing is shot... replace the tensioner.

 

You can also pinpoint the by using a stethoscope or piece of tubing to the ear to listen where the noise is coming from.

chevyblues[sm=burnout.gif]

 

Before you replace anything I would get some WD-40 or penitrating fluid, and spray a little on the belt, this will make it stop if it is the belt. permant.As you have replaced the belt already if it does stop look at your pulleys and see if they have any grooves, then take the belt of and see if you can make any of them wobble with your hand. If I was to guess on a bad pulley I would guess the tensioner, though.