I have an 03 silverado with an lb7. It has about 280k on it, recently replaced injectors, drove it maybe 200 miles and got bad fuel and have been chasing problems since. Injector clogged, fpr, fprv, ficm...replaced all of them. Truck also blew insane gray smoke that was straight un burnt fuel and would dump black fluid out of the exhaust if I ran the engine up to 2000 rpms. I have a fass 150 on it, banks big head waste gate actuator, 5 inch straight pipe exhaust, intake, and edge juice with attitude cts. I just started the truck after it sat for a few months since it still ran rough, checked my balance rates and no 1 inj was +15 and the rest were -7....my thought ok bad injector, they were diapco injectors. And maybe the return lines were leaking and dumping fuel in my oil, and stuck injector was forcing fuel out my exhaust valve. Tore it down, cleaned all injector tips in ultrasonic cleaner and they looked great, put them back in with the supposed bad injector in a different spot, started up and same rough idle and balance rates were the exact same. Time for a compression test.....and cylinder 1 had 0...I mean 0 compression. Tore it down again, pulled inj cup out and of course antifreeze filled the cyl. Well since I pulled my glow plugs already I figured why not blow air in the injector hole and push the coolant out through the glow plug hole. That's where things got crazy. The second I hit the air I could feel it push through my intake where my cac piping goes into the engine since I had removed it, put my hand over it and boom, it starts coming out my exhaust. Rotated the engine and no matter what position my valves are open on intake and exhaust on no 1 cylinder. Put an inspection camera down the inj cup hole and notice a shiny spot right in the middle of the piston.... how the heck did this happen and am I wrong to think I'm looking at new valves, probably new head, and if I busted a valve face off then new pistons and serious block work?? If so old dirty will be sitting up for a long time...and if I'm going with a rebuild is there any sense in throwing stock parts on since I plan on bigger turbo/fueling in the future? If I have to rebuild I might as well go big or go home right? Thanks guys. Can't wait to get some input and advice.