Here's one I haven't seen yet. My partner's (work partner that is) '02 Forester with an EJ25 shredded the a/c belt. He asked me to help him replace it as he was unfamiliar with how it goes on. I coached him in removing the belts and how the tensioners work. When I reached down to remove what I thought was some shredded belt, I was surprised to find something else....the idler pulley had shattered circumferentially along the center!

 

I never saw an idler break like this before on any vehicle I have owned. The plastic attacher was intact. I surmise that the bearings seized and the belt pulling over it caused the stresses to get great at the weakest point, which was the center of the pulley in the V slots.

 

Has anyone else seen an idler break like this?

See them quite often at work. Sometimes they make a real mess of things if the pulley gets cocked sideways then gets flung in some random direction. I've seen them go through radiators before. (Well, not THROUGH the radiator, but it wedged itself about an inch in. Busted the fan all to pieces too.)

Usually the bearings just seize then the pulley melts itself on the outer race. It flings nylon everywhere, chucks the belt and then after losing power steering do the owners finally have to have th car towed to the shop to be repaired. Rather than just driving to the shop a month or so earlier when the bearing first started groaning at them.

Here's one I haven't seen yet. My partner's (work partner that is) '02 Forester with an EJ25 shredded the a/c belt. He asked me to help him replace it as he was unfamiliar with how it goes on. I coached him in removing the belts and how the tensioners work. When I reached down to remove what I thought was some shredded belt, I was surprised to find something else....the idler pulley had shattered circumferentially along the center!

 

I never saw an idler break like this before on any vehicle I have owned. The plastic attacher was intact. I surmise that the bearings seized and the belt pulling over it caused the stresses to get great at the weakest point, which was the center of the pulley in the V slots.

 

Has anyone else seen an idler break like this?

 

Yes it happens. It is not an unusual failure.

Another good point made. I work on L/G tractors a bit. The arbor bearing assys wear or seize. The seized bearings wear into the housing and the blades eat into the deck and people just keep mowing. The main belt overheats so much before it fails it warps the crank pulley. That pulley overheats the engine ruins seals etc.