bleepster

iTrader: (2)

2002 Firebird, 3800, auto trans

not sure if its a belt squeal, or pulley squeal.
about a month ago I had to replace my alternator for bad bearings. while i was at it I replaced the serpentine belt. things were good.

this past weekend - i fired up the car and we took it on a 200 round trip road trip and i could hear squealing again - only on fast acceleration, and at shift points. in between shifts and while cruising, no squeals.

Yesterday, i popped the hood and fired it up. I sprayed the belt with belt conditioner and the squeal reduced greatly while revving.

i did notice however that my belt seemed to be bouncing around. from the alternator to the crank - that's the longest stretch of belt where it makes no contact to other pulleys. i bet that belt was bouncing up and down maybe 1" in either direction.

idler pulley didn't seem to move.

is this type of behavior normal for a belt?

is my idler pulley going do you think?

could use your diagnosis help.

thank you

bleepster

iTrader: (2)

Wife drove car to work today - 20 miles highway (70 mph) squealing again.
not sure what to fix or look at now.

HELP

thanks

blackbyrd

iTrader: (14)

could be the belt tensioner (pulley right under the alternator).

If its not that it could be one of the idle pulley. If its squealing at idle the best thing to do is to get a mechanics stethoscope and see if you can pin point the noise.

odds are the tensioner or one of idler above the A/C is starting to give

bleepster

iTrader: (2)

THANKS - i'll borrow some stethoscopes and see what I can find. idler pulley above AC is new and so is the alternator. I hope neither of them are the culprits. first alternator i put in was a rebuilt, and it was making a knocking noise. replaced it with an OEM new one and so far so good. I hope its not that squealing.

blackbyrd

iTrader: (14)

^than its likely the tensioner being the culprit. The other remaining pullies (water pump,AC, Power steering, and Crank) would give you some other symptoms along with it.

Give the stethoscope a shot and it should shed some light for sure.

bleepster

iTrader: (2)

picked up a pair of stethoscopes. its DEFINITELY the idler pulley above the AC compressor.

i'm swapping it out tonight - will post the results later

Ws6Guy!

I also have a pulley noise and cannot figure out where it’s coming from!! My serpentine and ac belt both look brand new so I didn’t mess with those. Replaced the tensioner pulley, idler pulley, ac tensioner pulley, and ac idler pulley. Also the alternator is new. Still squeaking and cannot figure out from where. Any good way to diagnose? The squeak is better than it was but still there

Racer-X-

First, get a stethoscope and check the idler pulley and the tensioner pulley. Sometimes new ones of those have been sitting on the shelf so long, the lube kind of runs to one side and they'll be noisy for the first 10-20 miles, so it isn't bad to drive them some before you write them off as "squeaky."

If none of the pulleys is the source of the noise (from the bearing area in the center), and none of the driven loads (power steering, alternator, etc.) are the source of bearing squeak, the next tool is the straight edge.

With the engine off (and battery negative disconnected to prevent accidental starting), place a straight edge across each pulley and make sure the belt is straight with the straight edge along the way to the next pulley. You may find one pulley is out of line with the others. If only one idler or load pulley is out of line, you can shim that. If the crankshaft pulley is out of line with the rest of them, you've got a harmonic balancer/pulley issue and that needs to be replaced.