G.T

While trying to pinpoint some
intermittent noise coming from my engine compartment during cold starts, i noticed an Accessory drive belt idler pulley wobbling a little bit while the engine was running (the grooved one to the left of the power steering pump pulley)

i immediately got and installed a new pulley (P/N: 1L2Z-6C348-AA), and even the new one is wobbling!

i have no signs of belt dust anywhere, no slipping or any other issues.. all other pulleys are fine by the look of it.

i've never had issues with this particular pulley, and i've never had it removed during the S/C installation.

Any idea how to fix this?
i'm hoping a washer or a bolt replacement is all there is to it

281GT

I listened to the audio of your clip there and mine made that exact same noise.
I listened to it with my automotive stethoscope and it was defintely coming from the bearing of one of the idler pulleys. The dealer replaced the idler pulley assembly and the noise stopped for about a week. It did it once after that and I haven't heard it since. That was almost a year and half ago.
There are higher quality aftermarket idler pulleys available. Motoblue makes them. Not only is the pulley of higher quality so is the bearing. They have noticably less drag than the stock units. I plan on switching to the aftermarket units but since they have been quiet for me it's a low priority.

Lime GT

When you had the belt off to change the pulley did you try rolling each of the other pulleys separately slowly to see if they feel rough? Also spin each fast to hear if they rattle which could indicate a bearing starting to go bad. Sometimes the grease dries out and the bearing will start to fail. Most of the idler pulley bearings are ball-bearing so a very slight wobble should be normal, as they're designed for rolling load, not side load.