coolent
 

i tried flushing my cooling system today in my 98 F150 5.4L. i ran a cleaning soulution through in, drained it , then ran water through the system. i realized after that during this process, i ran cold water through the engine while it was warm, could i have cracked the block or worse by running cold water through a warm engine? and why after all this i still have a browm tinge to my coolent? would love some help on this one guys!!

it will be fine, the block is thick enouf for that as long as your engine wasnt to the over heating point, but if it was at normal operating temp you will be fine. if your still worried just run it for a week and check the coolant level. but i wouldnt think twice about it you are fine.