The chirping toilet
For several weeks, shortly after a flush, my toilet would make a loud chirping noise for about 30 seconds. It flushed perfectly and did not have constant running water or any leaks. The noise stopped by itself a few months ago.
-- What was it?
-- Why did it stop?
-- Is some part slowly going bad?
(I found a similar question in the archives the other day, but can't find the thread today for some reason.)
Can't be sure, but it was most likely your fill valve, which opens to allow water to refill the tank after each flush.
The cause could be a bit more elusive. Sometimes, not having the valve for the water supply at the wall open all the way can cause something like this. Sometimes, it's water pressure that's too high. Sometimes, some bit of crud may have lodged in an important area of the valve and cause the vibration. There are other possibilities as well, depending upon the valve type.
I had a similar experience with the valve on my toilet, starting a few weeks after it was installed. It was intermittent, but I just swapped the valve for a brand I preferred and it solved the problem.
That your problem disappeared could indicate that whatever it was has resolved itself for now. If you don't have any symptoms at the moment, I would say, "It ain't broke, so don't try to fix it."
If it recurs, come back to us with more information about the type of toilet and valve, and we can give you some advice about maybe cleaning it or, if necessary, replacing it, which is almost always about a ten-minute job.
Thank you very much for the comprehensive reply, wjcandee. I agree with leaving it alone since it's fine now. Just wanted to explore whether there might be some huge iceberg of a problem below the quiet surface.
Hope all is well with you in NYC. You've all been in our thoughts since Superstorm Sandy.