Im sorry if theres already a post with this questioned. i searched it and couldnt find it. Im having an Issue. i just bought a truck. i dont know how often it was used before i go it. it was owned by an older guy who kept great care of his truck. its a 2000 GMC Sierra ext cab Z-71. its got the 5.3 in it. when i bought the truck i found an exhuast leak right where the pipes from the manifold come together at the Y pipe. theres a coupling there that has a leak. there was Black water comming from it. i wiped it and smelt it and it was just water. couldnt smell any kind of oil. the oil was just changed about 1.500 miles ago and was still in great condition. couldnt find a problem anywhere. any kinds of leaks. there was a lil oil by the drain plug where they drained it and a light film on the filter also. other than that nothing. doesn anyone have a clue of where this " BLACK WATER" could be from? i cheacked after i drove it an hour on the highway to take it home and nothing and a few days later and nothing again. Any help is greatly appreciated.