We just moved into a new apartment. The water heater is not extremely old (12 years old). The water heater stopped working a few days ago. We tried to light the pilot light, which worked --but than went off after releasing the overide button. We purchased a new thermocouple, but we are experiencing the same problem as before. The flame is blue - which is a good sign. I am not sure what is going on. Maybe something is clogged/blocked. Not sure. We need showers, and hot water to wash clothes and dishes. So I am really hoping we can fix this problem ASAP.

Is the pilot flame strong? Does it have a good size and sound? If the pilot is weak then it will draft off the thermocouple and lose connection. The best way to clean the orifice is with a small torch tip cleaner, if you don't have one then what ever you use (safety pin or straight pin) needs to be as small diameter as possible and care taken not to widen the opening. Let me know how this works for you please.