Regarding secondary and in some cases a third pump failure I sometimes wonder if a combination of not reading the service manual and Chevrolet (GM) contributing to those failures.
Up untill sometime in 2014 the water pumps were not packaged with either the gasket or replacement fasteners.
The no gasket thing drove mechanics nuts.....why in the world would a part that requires another part (gasket) to be installed not be packaged with same?
Especially since water pumps, new or rebuilt, have always been packaged with gaskets.
So, mechanics had to remember to order a gasket along with a water pump.
I think that bit of aggravation added to the being unaware that the pump retaining bolts are one time use, torque to yield + X degree type fasteners.
Repairmen expect TTY fasteners being used on cylinder heads and major, high expansion/contraction areas, but never on a water pump.
So, fasteners for that position have always been re-used.
Problem with re-using a TTY is that it is stretched already......so it can no longer maintain a stable clamping force.
As a result, the fasteners end up applying a different clamping force at each pump mount ear and, being aluminum, the pump housing ends up warping over the heat/cool cycles........this in turn, creates a secondary failure.
I suspect I'm correct because at the same time Chevrolet (GM) began packaging the pump along with a gasket, they also began packaging the TTY fasteners. This change occured sometime in early 2014, along with a new part number and nomenclature that included the word, 'Kit'.
It probably took 3 months for the original, no gasket or fastener pumps to clear the parts stream.
I have noticed that the pump failures reported on the forum have dropped way down, and secondary failures have dropped even more, so, between the re-designs and fasteners being supplied there appears to be progress.
I'll keep watching,