I'm really curious what this noise is. I've got no loss of performance, it just doesn't sound like a normal thing, which concerns me. I thought it could be a bearing failure, but when bearings fail, i'm used to hearing more of a 'whirl' sound, not usually 'chirpy'.

This noise has been a thing for a while, especially after a long drive, so the engine is plenty warm. I don't hear it (usually at idle), until I've been driving for more than say 20 minutes. In the last 3 months, in addition to regular maintenance, I've replaced the alternator and the motor mounts, as well as both belts. I've got a stethoscope, and I've listened to each belt driven accessory. While I'm not a car mechanic by trade, none of the accessories sound like the culprit to me.

The only other option I haven't explored as deeply is a lean condition ping. I haven't found any sound clips that are similar to mine, so if you know of one, please share.

https://www.youtube.com/watch?v=uaGG...ature=youtu.be

 

That's not a good sound but because you see no loss of performance I doubt its compression related. I would guess a vacuum leak? Any engine codes?

 

No engine codes according to the accessport. I'm unconvinced it's vacuum related, as I would think the noise would be more pronounced at a cold start up if that were the case. My logic could be flawed, but I'd expect sealing to get better with heat expansion, not worse. This weekend, I'll try tossing around some WD-40 in the engine bay and see if I can locate the culprit.