Ruined Batch?

I did a partial mash steam ale. I decided to naturally carbonate it in a keg with 1/3 cup of corn sugar. I let it set for 3 weeks. After trying it, it was flat. At that point, I force carbonated it @ and relized that the keg was leaking air. It did carbonate, but it tastes terrible. I am guessing that it oxidized while sitting for weeks in a leaky keg. It tastes like an acidy metal. Is that oxidation? Am I going to have to dump 5 gallons down the drain or should I wait it out?

Oxidation is more of a wet cardboard flavor. Metallic flavors are generally do to dissolved metals. The main sources of metals are: the water, the kettle(s), the wort chiller, and the keg. If you haven't had this problem before and you are using a wort chiller, copper oxide might be the problem. If you have an aluminum kettle or tun or you really scrubbed out the keg, you can leach aluminum before the oxide layer re-forms.

Even though your keg was leaky, the CO2 being created by the yeast should have kept the O2 out.

I doubt it will get any better, but unless you need the keg for a new batch, give it a few more weeks.

My neighbor ruined several batchs that were in his pipeline before he tasted any. Turn out the metalic taste was caused by a chip in the bottom of his enameled pot. A little rust goes a long way towards ruining brews. And in the words of the the holy bible, "TASTE YOUR BREW", at every step. Eat grains, sip mash, sample wort, have a glass out of the fermenter.... educate your palate, and find or eliminate problems early...

I agree with casebrew. You have to be PART of the process. Taste everything from boil to bottle. I just siphoned to a secondary, and what was left in the tube was pretty damn good. I could taste the hops, and the flavor was so fresh, it was incredible! Like I held the hops to my nose and sniffed.
Man, I love this hobby.

I did taste the wort at each step and it tasted fine until it sat in the keg. Maybe a bacterial infection?