I have a 1989 Z71 which water pump gets pinholes in the back of every 6-7 months. Checked the water coming out and it was a metallic almost rust looking color. Flushed out the system and drained radiator. Any suggestions to what could be causing both the rust colored water, and why pinholes appear on back of the water pump? I think both problems are related cause have no idea why pumps continually get leaks in the back.

 

What antifreeze are you using and mixing with tap water or distilled?
How long have you owned it?
How many pumps have died?