I drained the coolant using the drain plugs on the block and the rad. I then ran water from the hose in the expansion tank to that it ran out the engine block. I torqued the black plug down and ran coolant in the expansion tank and out the rad drain plug.

Question: Is it now sufficiently flushed, or can i start it up with water running in the expansion tank and out the bottom of the rad with the heater on to further flush it?