Howdy folks, I'm doing an alternator swap because obvious. In removing some parts from the donor car, I thought I'd salvage some of the bushings that I put in brand new two years ago. The nut that came off the donor alternator looks... stretched. Like it's slightly oblong and not perfectly round. This is the best picture I could get, that's not perspective distortion you see, that's how it looks.



This is the second one like this that I've found so far. They fit a 13mm socket with no problem, so they're not THAT out-of-round, and they seem to hold the bolt threads OK, but I'm wondering if this is a potential failure down the road.

 

Are you sure this is not a self-locking nut? I have seen some self-locking nuts that are slightly oblong.

 

Self-locking, like the kind with the nylon insert, or with the "teeth" under the flange? This is neither, just a 13mm smooth flanged nut. If the oblong design is supposed to be self-locking, well, mystery solved. If not, like I said, it seems to hold the thread just fine and isn't loose at all, and I don't see how load stresses would make them oblong in the first place, as both of the ones I found were on the end of the long bolts run through the mounting bushings on the AC pump, power steering pump, and alternator.

 

There are multiple kinds of self-locking - including the ones with nylon inserts. Typically I see the oblong ones used in harsh conditions such as suspension components. I don't recall seeing any on the accessory mounts though.