I have had this squeal that just started in my truck just a couple of days ago and it is driving me insane. I replaced my water pump about 2 years ago, my idler pulley about a year ago, my fan clutch about 1-1/2 years ago and my serpentine belt about 2 months ago. Here is a link to a you tube video I shot this afternoon of the noise. http://youtu.be/nTXXEnvAiNM

I thought that it might be the tensioner pulley/assembly? It doesn't seem to be affected by A/C. I noticed that it didn't really start until I put the truck in drive and began to move but once it starts it doesn't stop. It is definitely coming from the passenger side of the truck in the belt area. One last thing, I noticed that I have been losing coolant. I am not sure if that could be playing a role in the problem. Any suggestions would be greatly appreciated. Thanks!

 

Does sound like a tensioner.

Loosen the belt, spin the tensioner. If it is rough at all, it is the tensioner.

First, get a 2-3 foot long piece of hose, half inch or smaller, something flexible, put one end by your ear, the other end drop in the engine compartment and move it around, you will be able to isolate where the noise is coming from better. If you can plug your other ear while you are doing this, it makes it easier.

When I say drop the other end in, I don't mean let it hang free, guide it with your hand, don't let it or your hand contact the moving belts, pulleys or fan.

Not trying to talk to you like you are not intelligent, but I don't want to get sued. hahaha... just sayin.

 

Check the alternator shaft bearing.

blacksmoke

 

you can get a spray bottle, fill it with (water) and adj to stream.

as truck is running and making noise, spray the stream of water onto the different points, belt, bearings, etc:

many times the water will cause the noise to stop for a short period of time.

will not hurt engine or belt.

worth a try!!!!!!!!!

 

I second this one,,,,and also antifreeze on a belt from a leaking water pump will make a belt very loud, if nothing else wash the belt down.

 

Yep, I was also going to advise spraying a little bit of water on the belt. If the water stops the noise, it's either a belt problem or a misalignment problem. If not, I'd be looking for a noisy bearing. The most common failure seems to be a tensioner that is worn where it pivots. As the pivot wears, it will tend to push the belt more to one side or the other.

 

Could be the water pump causing the problem. If it leaks it will soak the alternator pulley. Look down the left front side of the engine, directly at the alternator. If the water pump is leaking there will most likely be a rusty stain on the side of the airbox, to the left of the alternator. If it's there, replace the water pump and belt at the same time. There's a write up on the water pump in the 3rd gen engine and drivetrain.

 

Thank you everyone for all of your insight. I tried pretty much everything. In the end i used a piece of hose to isolate where the sound was coming from. It turned out to be my water pump! That, I guess, would explain my coolant leak as well.

Totallyrad- I did notice rust on the side of my airbox. Great indicator!

madhat- That trick about the hose was priceless. Thanks again.

I hope that I can contribute at some point to someone elses problems. You guys are great. Off to the parts store...