Not sure how you made out, but I would try flushing from the engine back to the water pump. The lower radiator hose would also be a "must check".
The primary passage from the water pump is into the cylinder head. You can pull the engine coolant temperature sensor (at the back of the head, below #6 intake port) and flush back from there. I haven't checked, but imagine this is a pita to get to.
“The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed.”
Originally Posted by Mike Miller
I just don't know what I'd do with 560 hp that doesn't involve getting arrested.