Saw a short youtube vid about a fellow attempting to flush/drain his cooling system via the tube on the bleeder valve instead of pulling off the hose to the pump. (It didn't flow and he never followed up). Has anyone ever tried this, heard of it, seen it? My thought is that you would have to continuously add coolant through the top, (since I'm not sure it would simply drain too well through the valve) as the engine would likely have to be running (wouldn't want to run it with extremely low coolant).
My reason for considering it would be mainly to start the process, save having to have the entire contents of the system come out that hose when disconnected. I have animals, my neighbours have animals, lots of wildlife here in the mountains. Since I would be working outside I'd rather minimize the amount of ethylene glycol that could spill and cause any kidney problems if ingested.