I've been having some repeated issues with my cooling system. I had my radiator cored and rebuilt, etc. because it was clogged and the car would run about 220 all the time and overheat in traffic. Since doing that, I've determined that I must have a buildup of rust and sediment in the block because it will do great for a few weeks, running at 180 or lower, then eventually will start to run consistently at 200, then 210, 220, etc. and I'll drain the coolant enough to see that the passages in the radiator are clogged with sediment. I'll drain the coolant, flush the radiator out as best I can using a garden hose/pressure washer(carefully) and It will spit out a lot of debris. Then it's fine for another few weeks until the whole thing happens again. I contacted the radiator shop and they recommended that I flush the block to remove the sediment in the rest of the system. I would rather not pay them $125-$150 to do this, and I'm sure it can be done at home. They mentioned they use water and air pressure and go in through the thermostat area. Has anyone done this? Any tips at all for this process? It's a chrysler 383 if that is of any importance. Thanks!