Robotic(ish) sound after cold startup

Hey y’all.

So on cold starts or after the truck sits a while I hear this.. almost robotic / hydronic sound. It doesn’t happen during warm startups, and only happens a few seconds after the cold startup.

anyone know what could cause this sound? It’s more evident in the cab.. and the dang birds outside ain’t making life easy haha. You can hear it toward the end of the video.

just trying to get an idea if something is going out. Thanks!

https://youtube.com/shorts/ekGuIanW6JU?feature=share

 

Does it sound like a vacuum? If so its the secondary air injection system (SAIS). Its for emissions, look up the uni filter mod for it to help it last longer.

 

What I'm hearing and from what you describe it sounds like the Secondary Air Injection pump, it runs 30-60 secs at cold startup to help the catalytic converters heat up faster.
Yours being a 13 it should run a few secs when you turn off the engine as well to purge moisture from the lines.