[ZO6_Vette]

Hey all,
While checking out my 2013 4runner's running engine, I noticed that the serpentine belt idler pulley next to the alternator was moving forward and backward while the engine is running.

Is this normal?

Below is a small video from my camera.

4runner Idler pulley wobble - YouTube

Thanks

[Ducmonsta]

I doubt it actually wobbling. It's probably an optical illusion because of the difference in where the belt rides and the pulleys finish. You can check this easily by holding something stationary and compare it to the pulley (while its running). Just don't drop whatever you're holding ie. a wrench.

[lilsid112]

+1 on it just being an illusion.

[stevec5000]

It could be moving if there is a lump or defect in the belt but we'll never know since there is no video.

[ZO6_Vette]

If you look at the video and focus on the center bolt verses the edge of the pulley you can see it moving.

I can also wobble the pulley by hand with the engine off.

[timelapse]

Did you ever end up replacing this pulley? I just noticed my 2014 has the same wobble and I was about to replace it. Everything spins fine and doesn't make any unwanted noise, so perhaps the slight wiggle is normal. I have 193k.