Another cold weather noise

[Bolt snapper]

This is the second Winter that I've owned my 2011 5.4 XLT. The sound that's vexing me now began intermittently in the late Fall when it would occasionally sit outside overnight and the temperatures got to freezing or below. This past week, the outdoor temperature plummeted to below zero. Now it does it at every startup, and continues until it is well warmed up - at which point it seems to completely go away.

I hate trying to describe sounds, but the first thing I can say is that it isn't a steady, consistent "tick" or "tap". It is more like morse code - kind of a random pattern, almost like popcorn popping, maybe. It sort of sounds like it could be originating from the drive belt line. I remember an old Chevy we had when I was a kid that had a water pump go bad that made a sound like popcorn popping shortly before it failed.

Again, it goes away once the engine is fully warmed up (not just partly - I can drive 10 minutes after startup and still hear it). Because of the randomness, It doesn't sound like lifters or even an exhaust leak. It doesn't really sound heavy or overly metallic, either. More like a zip tie intermittently getting caught in a belt driven pulley or something.

I'm hoping someone can say "oh yeah, I had that and this is what it was", rather than spend a lot of time outside trying to figure it out when it's this cold! Thanks for any input you may have!

 

[Bolt snapper]

Got a few minutes today to work on troubleshooting this today. I started it in a 40 degree garage, irregular ticking started immediately, followed by a loud howl that lasted about a second (it's been doing that lately, too, with a cold startup). Pulled the belt off and started it again. Quiet as could be.

I changed belts and idlers, tensioner last summer, and I remember thinking the belt was somewhat shorter than the one I took off. For some reason I had kept the old belt. Put it back on and it is super quiet again.

I'm guessing - especially by the "howl" - that the belt was too tight, or even if it was the right tightness it was too tight on a bearing which for sure caused the howl, and maybe the tick.

I spun everything by hand and nothing seemed too rough or concerning. If the belt was too tight (cheap Amazon belt), have I already done irreparable damage to the alternator or some other component?

 

[99WhiteC5Coupe]

Got a few minutes today to work on troubleshooting this today. I started it in a 40 degree garage, irregular ticking started immediately, followed by a loud howl that lasted about a second (it's been doing that lately, too, with a cold startup). Pulled the belt off and started it again. Quiet as could be.

I changed belts and idlers, tensioner last summer, and I remember thinking the belt was somewhat shorter than the one I took off. For some reason I had kept the old belt. Put it back on and it is super quiet again.

I'm guessing - especially by the "howl" - that the belt was too tight, or even if it was the right tightness it was too tight on a bearing which for sure caused the howl, and maybe the tick.

I spun everything by hand and nothing seemed to rough or concerning. If the belt was too tight (cheap Amazon belt), have I already done irreparable damage to the alternator or some other component?

Lesson learned - use OEM parts.