Its draining right now. I cleaned out the sludge, it may have come from the hoses.
I am not going to do a full flush, I am going to dump the radiator to dilute it, and see how it looks.
Totally off topic, but my Grandpa had a pair of binoculars stamped "Made in Occupied Japan" back in the day. As a professional statistician and Deming acolyte, it's amazing to track the history and progress of data-driven processes. Back to...
Tough to tell without a recording as there's a multitude of "possibilities", but here's my experience with rotational scraping...
https://forum.ih8mud.com/threads/parking-brake-re-assembly-tips.1265971/