This is my first official my beer is ruined thread. I've been brewing for just short of a year and have brewed about 12 AG and three extract batches. I purchased two kegs off of craigslist a few months back from a disgruntled ex-wife that kept them outside. They were dirty and had some corrosion, but for $15 I had to take a chance. Long story short, I brewed an amber that I've made a few times and is one of my favorite beers. I let it sit in the primary for six weeks (yes I know, mistake #1) due to lack of time for restoring the keg. Ten days ago I tore the keg apart, removed all interior corrosion with steel wool and gave it a good scrubbing with hot water and "organic" unscented dish soap. After an inspection with a mirror (for the top part of the keg) and a mag lite, I deemed it beer worthy, gave it a good soak with starsan, and racked the amber.
Tonight I decided to try a pull to see how it was coming along.... As soon as I smelled it I new something was wrong, apple juice that has gone bad. The taste was even worse, it had a very acidic, solventy, with a hint of metal taste. The only two things I can think of are obviously the keg itself or letting it sit on the cake for six weeks. I have let beers go in the primary for a while before, but have never encountered a taste like this so I'm obviously leaning towards the keg. If it is the keg I can live with it and toss them, but I'd really like to figure this out before I rack a DFH 60 minute clone into the other keg that I "restored." Any help is appreciated.