Pulley/belt area problem??

[gth]

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...???

[Jansen]

Try the power steering pump. On a cold start my power steering pump sounds like a damned coyote howling. Once warm it settles down. The front seal on my pump is shot but I'm not sure if it went into the bearings or not. That is what causes my howl. I filled the pump full (completely full) and it seems to have helped.

 

bye the way, the pump wasn't low on fluid just leaking. So if you checked it, it might not have shown low.

 

Jansen

[Bish]

Stethoscope is a great idea. It could be alternator bearings, idler bearings, or tensioner bearings. The bearings are sealed but it is fairly simple to remove them and take the seal off and re-grease them. That would eliminate two of the possibilities. 30 minute job max to do those two. They are also reasonably cheap to replace ($15 and $30 IIRC). If it still squeals, probably alternator IMO. Let us know what you find with the stethoscope.

[Indy]

I had a grinding sound on my '99 with 135,000 KM last summer. My mechanic friend and I used a stethoscope and thought the idler puller and tensioner were the culprit. I replaced them but the noise continued to get worse. It turned out to be the water pump. If yours has never been replaced that may be the problem. They usually start to leak through the bearing and seal when the noise gets loud.

[gth]

Thanks for the replies,

 

I will try to diagnose this problem Friday or Saturday when it warms up a bit. Its currently -25F here.........

[jjrobo]

There was a post somewhere in the forums about greasing the idler/tension pulley bearings. I helped a friend do this and it took care of his noise. Mine is making a light squeal for the first 10 min now and I am going to do it as soon as it warms up a little.

 

Good luck