Hi.
My radiator is hot at the top and cold at the bottom.
I took it off and attached a hose and rwn it fot 10 minutes
I replaced the radiator and the bottom was roasting for a short while and it is now cold again.
Does this mean the sludge did not come out?

Hi

It would appear from your description that you have steam heat. If this is true then you have too much water in you system. It would have to be drained at the furnace and the water control checked to see if operating correctly. This should be checked by a qualified tech and replaced if needed.

Good luck

Chuck