My 1998 Silverado Z71 with 5.7L just developed a big problem. Wife drove it back from town, arrived home in a cloud of steam from under the hood. My first thought, due to the location of most of the water spray, was the heater hose fitting on top of the engine near the front on the passenger side. (I replaced that fitting and both heater hoses a few months back). After letting it cool down I pulled out the garden hose and refilled the radiator, then cranked the engine. I soon saw oily water running off the bottom side of the engine. Closer inspection showed it was coming from the base of the casting where that heater hose connection screws in.
With the engine off I got a flashlight and inspected that casting, and it appears there may be a chunk of metal gone from it adjacent to the edge of the rocker arm cover. Can't get a mirror in there to confirm it. I checked the oil, and there doesn't appear to be any water on the dipstick. Looking at the puddle behind the truck, it definitely is engine oil coming out with the water.
Any ideas on a fix, or is it time to throw out the truck and start over?