This "how to" covers removal and installation of a water pump on 96+ vehicles with the 4.3L V6 Vin "W". Some of you may recognize this procedure, because I've posted it several times. Thanks to DevilMan13xx for taking pics to add to it, I believe that it is now threadworthy.
1)Drain the coolant:
2)Remove the shroud:
7-10 mm bolts
the other 3 are on top in the front, cant miss em
no shroud
3)Remove the fan and clutch:
There is no need to separate the fan from the clutch. The whole thing threads on to the end of the water pump. I don't know the size, because rather than break out all my wrenches, I just grabbed an 18 inch crescent wrench. Place the wrench on the nut and tap loose with a hammer. the tapping will break it loose. You have to tap it, if you just try to loosen it, the belt won't hold it and the whole thing will turn. After it breaks loose just spin it off.
no fan or clutch
4)Break loose the bolts holding the pulley on:
4- 13 mm or 1/2" bolts
Just break them loose, don't remove them
5) Remove the serpentine belt
6) Remove the pulley:
Finish removing the bolts holding the pulley and remove the pulley
7) Disconnect the hoses
MAKE SURE YOU HOLD ONTO THE PLIERS!
8) Remove the old pump:
4-14 mm or 9/16" bolts
9) Clean the surface:
Remove all traces of the old gasket.
It would be a good idea to flush out the block and heater core while you're at it.