Note if you are running A/C that electric fan comes on when the ECU thinks it is required. Mine actually works, 1st time I ever heard it, and came on at 190ish yesterday with the AC on and the Disco parked. My wife prefers cooler temps me I just run without most of time.

But I would pull the thermostat and start with a flush, from the upper rad hose, for the rad then the upper thermostat connection and then lower rad hose (re-connect the upper hose 1st) - give it a good 15 minutes at each.

Use a catch basin, you want to see what if anything comes out