I flushed the system wuite well. Although it seems a drain is very helpful, it took a lot of water to come clean.
I put the garden hose in all the disassembled hoses and inlets, and with the wp removed stuck the garden nozzle into each of the four wp holes until I quit getting suds. Suds, I am meaning is white water. I typically held the fireman type nozzle into each open orifice ofmthe cooling system until the water ran clear. I did not attempt to even locate the drain on the block nor the radiator drain, as I think were mentioned in the Haynes manual, but usually just pull the lower rad hose to flush. It feels like I spent forty minutes with an estimated flow of a gallon a minute to get the cooling system clean. Now it is just sitting, iron block alum heads, awaiting a pump. Hopefully I wont get much, or any, rust in the system while it sits.
As for the Cobalt I serviced a month or two ago. I pulled the radiator hose, let it drain, then filled with tap water after reinstalling the hose loosely, then ran to the assumption of the thermostat opening,. I repeated this until the water exiting the system looked clear...aka no pink/orange Dex. Btw, just a few hours ago, after it failed to start for the third or so time and requiring a jump start, I left her running for about 10 minutes unattended and upon returning the temp gauge read abnormally low (like 70F when I estimate it being 200F+. And then I parked it again and left it running (with no AC) and returned and the coolant tank looked completely full. Fwiw, most if not all times I have looked at it in the past few months it has always been spot on at the middle/crease level. A few minutes later after killing the key, it returned to the normal level. So I suspect all the idling I did raised the temp really high and it freaked out the digital temp readout and the battery dying maybe killed the electric fan. Guess she got hot!
