toilet noise

[uok]

every time I flush the toilet, it makes a loud fog horn like noise, I have to run a tap for a little while to stop it, I suspect it's a air blockage some where,but I am not sure, am I correct and how do I fix the problem?

thanking you in anticipation

uok

[thedoctor]

See our project on water hammer and turn down the mains stop cock ever so slightly

[uok]

i was told else where to tap the ball valve with a hammer, problem fixed thanks