Cleaning out water jackets, with block outside car.

Princess Valiant said
Power washer through each hole with the freeze plugs out and water pump off the engine.

You'd be surprised at the pile of sand that will come out. A lot of the sand has been there since the engine was first cast.

Don't forget to remove the two threaded drain plugs at the very bottom of the block; one on each side. I don't know what they are called.