How do I stop that wailing sound when I flush the loo?

I replaced the siphon bit in the loo and since we turned the water back on and now flush the loo, we get the wailing pipes noise, very annoying! Should I try the coupling pipes idea? Thank you!
Lee, June 2004


done
The ballvalve has gone , when you had the water off to do the syphon the washer in the ballvalve will have fallen to pieces and is now causing the noise

Steve, November 2004