Pulling all the hoses, thermostat and whatnot will only drain a portion of the liquid. Once you have drained down that far, you have to drain the block. There are two block drains located on the side of the block, with the heat in the on position, opening those drains will purge most of the remainder of the coolant.
Each flush and drain requires the block drains be pulled too. This process can be very time consuming. Plan a full day just to do a coolant flush, unless if you have very tough skin on your forearms. Pulling the block drains while the engine is hot will produce burns.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.