How much effort you want to put into it is up to you. This is max effort once a year or so cleaning, or if you have issues.
Just general info what you should do once a year to keep your WC at 100%:
Cleaning a loop, not a new loop: I do this once a year, I drain and refill at 6 months, the next time I do this……
Wash hands very well, getting rid of hand oils.
For pumps and blocks, fittings, clamps, acrylic res/block parts.... not hose, tear it to smallest pieces, put in a bowl, heat water up not to boiling add 10% vinegar, when hot, pour over parts. Rinse in 10 min or so. Put aside.
The blocks will probably have some black oxidation. Take the copper parts out of the pile of parts you took out of the water. Dry well and pour ketchup on them, and set aside. Only the copper parts need this.
Rad cleaning: fill with very almost boiling hot water. Let sit 10 minutes, drain half out and shake for 5 min. Repeat till liquid is clean. You can pour it in a clean bowl and inspect the water if you like.
All the pump, block, fittings, and clamps, inspect, get in the tiniest corners with a tooth brush. Kind of meditative, time consuming, you learn a lot about o-ring size, how it all feels. It’s very relaxing with some mellow jazz in the background. Run a rag using a coat hanger and dish soap through the tubing, rinse well. I always consider replacing my hose every year. Plasticizers leach out, the tubing isn’t as flexible. Consider it a ‘Hobby Cost’.
Rinse all the parts and hose with distilled, dry then really dry with an air compressor (nice extra step to get rid of water spots). Don’t need to dry the inside of the hose.
Now on to the copper parts, they should have been soaking an hour or two. A toothbrush and ketchup should clean much of the oxidation. It probably won’t be like new, but pretty darn good. Rinse, dry, and blow the parts.
That’s it.
My Thermochill PA 120.3 has been sitting now for almost 7 months. I didn't get a chance to drain it before I deployed. I'll be home in 15 days to hopefully rescue it. I was using just a distilled water/ antifreeze mixture, so hopefully that's not too corrosive over time. Any ideas on how to make sure my radiator is 1) good to go and 2) cleaned properly? 
