Originally Posted by bismic

There are quite a few cases of the early 6.0L water pumps breaking off their plastic fins or the entire impellor coming off.

I think a coolant system pressure is the best test. I am just now considering the best place to get the coolant pressure reading so I can get some data. The easiest place is on my coolant filter, but that is at the end of the line. The best place is probably at the block plug - I just do not want to drain my system completely (at least not so soon after flushing it).