mine was like that too
. the only possible way of overheating ur car is if u dont add any water back in the radiator after u drain it
. my reservior was as bad as urs so i took it off and cleaned it with soap, my uncle told me to put some pebbles inside it and shake it so that way it could remove all that brown stuff that was stuck to the sides of the reservior. and it actually worked
when u flush it, u got to remove as much as u can of that brown crap.
like i said it will require several flushes, or u can drain the radiator fluid like i told u too, and take the cap off and put ur water hose there and turn the faucet on and u'll see all the crap coming out of the radiator, then all u have to do is figure out a way to take the water thats left in the block. after that it should pretty much be clean
and dont forget to add fluid back into the radiator
