How do I totally drain my cooling system

[Jay87LX]

I am doing a cooling system flush, I opened the petcock at the bottom of the radiator and let that drain, I dontr think even a half gallon came out, I then took off the overflow tank and cleaned that out, I then took the thermostat out and when I did that I took the hose and pushed it down so the fluid came out of that but I am sure there is alot left because I have rear heat so there are lines that go all the way back there.

 

[panda24619]

engine block plug. but i wouldnt do that. you sometimes break the block if its too tight in there.

 

[stamp11127]

Since you didn't get much out of the petcock how clean was the overflow tank?
If the system is loaded up easiest way to drain is by removing the lower radiator hose. That will be a chore in itself and somewhat messy. Mine was firmly attached and wouldn't rotate at the tank. Ended up cutting it in half to remove it. Put the new hose on and it leaked. Went old school and used regular hose clamps on both ends.