Rooster Crow on Startup 2019 4.6L

https://youtube.com/shorts/lQh_UcybgN0?feature=share

Noise started after a run-in with a fairly deep mud hole. On the drive out the engine was being a little noisy, which I mostly attributed to thick mud splatter all over the radiator. Another thing that happened was the battery/“charging system” light coming on intermittently and having slight voltage drops. Now the battery was a couple years old and had lots of nasty corrosion buildup on the terminals when I bought the truck and almost a year later I hadn’t got around to cleaning it, but other than that and potentially some extra water and grime, connections all seemed good. Never had any power or starting issues afterward though, besides the noise. Light stopped going on and off after just a few minutes and hasn’t been on since.

This all happened last weekend and now today I finally gave the whole engine a good cleaning and replaced the battery just for maintenance’s sake. Pulled the grill off and cleaned the radiator of all the mud as well as the many many bugs and other crud that have accumulated. Made sure the fan was all clear and my belt looks tight and healthy as well, but still getting this awful noise on cold starts as well as just slightly more high-pitch whine from the engine than before. Any ideas what this noise could be?

 

SAIS?

Really sound like the starter isn’t disengaging after it starts, like the bendix isn’t retracting.

 

Sounds like #1 from outside the car in this video. https://www.youtube.com/watch?v=f7bTSm-sHBk

 

Being the starter would make sense based on that sound, however due to 1) the fact that there’s some lingering tinny sounds/whine from the engine even after starting, and 2) the fact that I was recently pretty swamped with water and mud, is the SAIS more likely?

Should I pop ’er open and see if it’s full of water? Time to start looking into a bypass kit?

 

SAIS was my first thought based on the water fording incident. I’ve never heard that sound associated with it, and it sounds like the starter just continuing to spin after ignition occurs. The starter is thankfully not next to the SAIS on the 5.7, so an automotive stethoscope would be able to pinpoint where the noise comes from.