I wanted to replace the plastic drain valve with a new metal valve after flushing the water heater. The old plastic valve was destroyed during removal, so I don't have it for reference. However, I am not having much luck getting the new valve to go in. I am suspecting that this is because the sludge might be partially clogging the threads. Although I carefully cleaned it and shopvac'd it, I still cannot seem to get the new valve in. It just would not even catch the first turn. However, if I use a new plastic valve instead, and force it hard enough, I am able to get it to go at least part way. For now I am sticking with the plastic valve but I would really like the metal valve. Any suggestions on what the problem might be?
BTW, the flush operation was successful. The heater is not making nearly as much noise as before. I had to use my shopvac with a small plastic tube extension and sucked most of the sludge from the heater. Simply running the water did not do the job. There must have been about one quart of sludge (texture of fine sand).