Hi, all. I'm new to the forum and I hate to be a burden right off, but I have a 1996 Blazer (2wd) that intermittently makes a noise under the hood that reminds me a little of a power steering pump belt squealing, but its more of a "shearing/swishing bad bearing" kind of sound. Sorry, Im not very good at the description.

Anyway, I removed the one and only belt and the noise stopped. So I rebuilt the alternator and replaced the idler pulley and bearing in hopes the noise would stop, but it did not. That only leaves the A/C clutch, water pump and power steering pump. I also wonder if the cooling fan clutch might cause such a noise - I know I can frequently hear the cooling fan randomly speed up and slow down, like the thermal clutch isn't working properly but the noise I spoke of does not seem to change with the fan.

Anyone have any ideas on what this might be? It gets very loud sometimes and It's driving me crazy. My neighbor has an S-10 pickup that does the same thing and his mechanic can't find it either. Any help will be much appreciated.

 

Did you also replace the tensioner?
Are you getting any "weird" wear on the belt itself?

 

Yes I also replaced the tensioner and am not getting any weird belt wear. The belt seems to be running very smooth.
Oh, and i found a couple more words that better describe the noise "whining/whirring"

 

I have this same problem,
Although my 98 Blazer has 350,000KM on it... I have a new serpentine belt, Have not tried replacing components such as the tensioner or pulley.

One thing that I have noticed: This noise does not kick in until about 5 seconds after having first turned the vehicle on.

If you put your head in front of the radiator it is very loud, sounds like its coming from that area.

There is alot of moving parts here,
It seems to be alot worse when the truck is cold.
It may be getting worse,

Wondering what it is....

 

Best thing to do (as was suggested in another thread you commented in) is to remove the belt and inspect each pulley for signs of a bad bearing (gritty rotation, wobble, or play).

 

Is it kind of a metal scraping and whining sound??? If it is I'll bet it's that darn A/C Clutch rubbing up against the compressor. Does your A/C work???

 

Yes it is kind of a metal scraping, whining sound. The A/C works great. I can't see any evidence of the A/C Clutch rubbing against the compressor though. Should I be able to see it if it is? The A/C clutch is my top suspect though.

 

I have the same problem and I'm convinced its coming from the idler pulley. I have discounted the idler wheel itself as I put a new one on and still have the problem. However I have noticed that the wheel is only located by a kind of dished washer at the front through which the bolt passes. This washer only has the slightest lip to locate into the bearing inner race and I think this lip has worn down allowing the idler wheel to wobble when running, I can't really see it put can feel somthing if I take the belt off. Anyway, just my thoughts, I am going to the dealer to see if I can get a replacement washer, I will let you know how I get on.

 

Quick update, re-examined all the pulleys today and found a fair amount of fore & aft movement on the power steering pulley. its secure on the shaft but moves in the kind of way you would expect if a thrust washer had given up. Its only a $60 exchange part so I will replace it and get back to you. interesting thing is the noise is just as loud from the top of the engine as underneath, difficult to pindown so I hope this is it!

 

Power steering pumps have some play in the shaft. How much is "a fair amount"?