i have not done it myself on a 3800 but have on older pontiac engines, its all the same really. you just need to take the alt bracket, the 4 long bolts out from the water pump. the oil pan bolts and the bolts around the outside of the cover its self.


when you did the water pump, did you use thread sealant on the 4 long bolts? if not they could leak.

you could also add some dye to the coolant, then look for the leak that way.