coolant question

[dave1234]

I know this is a dumb question but where is the coolant drain for the engine (not the radiator draincock) to COMPLETELY flush the cooling system on a '89 F150 4.9 . Also why is my radiator full and I cant get any more coolant in despite running, circulating and letting cool but yet the over-flow stays empty even when the engine is hot- like its low on coolant- if the radiator'system is full, should not then the heated/expanded coolant start to fill the resivoir when hot? It isnt overheating or anything but I just like to do things right. One other thing I have trouble wrapping my head around is how the overflow can be non-pressurized- its open to the same system? Pressure exerts itself in all directions- how can you have a pressurized radiator, but the overlow is simply connected off of a line at the top/fill but is not?

 

[mikesheldon]

Currently many cars do not have a radiator drain plugs. There are aftermarket adaptors that you insert in to either the main radiator hose or some of the return hoses. What they do is allow you to put a regular water hose connection in place and then you run regular water through the system and then it lets you darin the water out and replace with the appropriate coolant your vehice requires. They can usually be found at most major auto parts outlets.