how would i know the labor hours needed to do this repair? 2002 trailblazer on 2002 Chevrolet Trailblazer

2002 trailblazer water pump, besides the mechanic telling me the labor hours it takes to do any repair how can i know that before i go to the shop?

Asked by for the 2002 Chevrolet Trailblazer
2 answers
I recommend, REPAIRE PAL , try this site
there are programs from manufacturers that give you that info.

go to a parts store for the info