I just changed the toilet valve on a toilet because it started to run constantly. Now it works properly, but it is very loud when it is refilling. Listening to the sounds, it *seems* to be coming from the piping and valve under the toilet (between the toilet and the floor).

Also, the sound does not start immediately when it starts to fill up; there is a 1-2 second delay before the sound starts.

Hi Xalthon and welcome, Try to completely open and close the valve a few times ( the one you used to shut off the water) and see if that clears up the noise.

Thank you, but it did not seem to work. I cycled it full on/full off many, many times, but the loud hissing sound still seems to be coming from that valve area below the toilet.

Well Xalthon, if you used a fluidmaster valve you might try this https://www.askmehelpdesk.com/plumbing/loud-noise-when-toilet-tank-filling-up-593818.html. Tom is one of our resident Experts.

Try creating the sound and then touch different pipes are parts to see if you detect any vibration. Could just be you new valve but might also be the washer in the shut of valve below the toilet tank.

Well Xalthon, if you used a fluidmaster valve you might try this https://www.askmehelpdesk.com/plumbing/loud-noise-when-toilet-tank-filling-up-593818.html. Tom is one of our resident Experts.

I had noticed that post before and tried it. When I opened my Fluidmaster up, it looked totally different (cap did not screw on, it's latched on; no visible seal; etc.). My guess is that they have updated their design perhaps?

Regardless, I opened it up again today to have another look just in case I missed something, but everything looked the same. After hooking everything back up, the loud noise seems to have dissipated. Now, when I did this, I also shut the water off below. So maybe something "fixed" itself when I cycled it on/off this time (even though I had done that many times before).

Anyway, it seems to be OK (much better anyway) now. Let's just hope it lasts!

Thanks all for your help!

I'm glad your good for now, I'll keep my fingers crossed for you. And thanks for the update it's always good the hear the outcome.

Never saw a Fluidmaster that screwed on, they "latch on" you rotate the top about 1/2" . When lift the top, the seal is the black round washer you see. You might have seen a ballcock design, the top is held on with screws.