[SOLVED] Engine Whine (RPM related)

[TVBeachFan]

Problem: Engine whine that gets louder as RPM's rise and decreased performance while accelerating. CEL is not illuminated.

When I first noticed the problem I started reading the forums here and on the OS. But, after searching I think I narrowed it down to 3 possibilities:

Idler Pulley
Tensioner Pulley
Fan Clutch



What I've tried so far:
1. Engine oil in the gas tank trick. (joking)
2. Removing the Serpentine Belt and spinning pulleys individually to listen for noise and wobbliness (is that a word?)

Results:
1. Nothing happened.
2. All pulley's sounded fine, but the fan did make a grinding type noise when spun by hand around a certain spot.



History:
Bought vehicle at 57k miles
currently at 90XXX miles

Spark plugs replaced (5k miles ago)
Air Filter replaced (5k miles ago)
Complete injection system cleaning according to the dealer (2k miles ago)
Oil changed every 5k miles or so
New serpentine belt (5k miles)
Changed Blinker Fluid dealer said it was bad (2k miles ago) (joking)

By the way I was kidding about the Oil in the gas tank and blinker fluid.

[The Roadie]

$20 for each pulley is cheap. Just do those first. A Harbor Freight stethoscope might narrow it down, but why bother? Shotgunning $20 parts (even times two) is a better use of your time than driving to Harbor Freight and spending two more hours farting around.

[TVBeachFan]

Thanks Roadie,
I was going to try the guess and test method first but I thought, just maybe, that the symptoms that I had might have narrowed it down to the Fan Clutch. I don't think I'm having the ticking sympoms that others reported with having problems with the fan clutch. However, I did forget to mention the occasional jet engine or turbo noise from the fan when starting. It goes away after a few minutes so I'm not sure. I'll take your advice on replacing the two pulleys, they'll probably end up going bad sooner or later anyways.
Hopefully this weekend I'll be able to change the diff fluids and TC after I get the engine noise problem fixed.

Once I get this fixed and get all the regular services done I'll get started with lowering the ground from my Trailblazer.

[The Roadie]

... I'll get started with lowering the ground from my Trailblazer.

One of my favorite air crew jokes is what the sleek jet fighter jocks say about helicopters: "They aren't really flying.....they're so UGLY the earth REPELS 'em!"

I aspire to that.

[TVBeachFan]

Thanks for the insight Roadie,
I took your advice and started with the cheap and easy fixes. First I removed the Serpintine belt, and replaced the Idler pulley. Then I re-installed the Serpintine belt, and started the engine. BINGO! The root cause of my engine whine was the idler pulley. After I compared the old idler pulley and the new, they looked identicle. No wear marks or broken/worn pieces visible. The only slight difference that I noticed was the old pulley was dirtier than the new (as expected).

Just a little helpful info to those who have engine noise related to the RPM. The symptom that I was having was an engine whine that was related to RPM. The whine was very similar to the power steering whine that you get while turning if you have low power steering fluid.

[TBYODA]

I thought I'd post in here to bring this up to the top for some of the new guys. My wife noticed last night that there was this whine while driving. I did not really notice it to much because I DD the TB. Anyway I found this thread and got both pulleys and a belt just case my current one was bad, it has 69K on it anyhow probably time to change it .
Well I replaced both pulleys and the belt. My current one did not look to bad so I will keep it as trail spare. Started up the TB and back to normal.