Tensioner and two failed water pumps?
 

Last year my water pump started making a rattling noise so I replaced it along with the fan clutch, since I suspected a fan with a missing blade was oscillating enough to put some uneven wear on the pulley, eventually leading to the spline/shaft failure on the water pump.

Less than a year later I'm starting to hear what I think is the water pump clicking again. Assuming the fan clutch, or the fan isn't the issue, could the tensioner be causing the problem? The spring or bearing on the pulley be giving too much or too little tension wearing out the water pump?

Any ideas on what might cause two water pump failures?

I take it this is a 400 we are talking about?

Steve K.