noisy toilet cistern

[collegekid]

Hi hope someone can help with this one.
When we flush our loo it fills up with water OK but it has started to make an awful grating, grinding kind of noise - hard to describe - a bit like a ships hooter !!
What can be the cause of this and how do I fix it please?

 

[Bon]

It's likely the inlet valve is vibrating. Lift the cistern lid off and flush the loo and GENTLY push the inlet valve to one side and see if this has any efect on the noise. You wouldn't believe the racket these can make!

If so replace it with one of these. Once described to me as the "Rolls Royce" of inlet valves! Admittedly this was by the guy I was buying it off!

 

[RigidRaider]

If you remove the lid of the cistern and press on the ball while the water is flowing, does it affect the sound?

If so, why not try just turning the mains down a little? There may be an isolator on the main feed to the cistern or you could try turning down the main stopcock, a small change in flow can affect the noise a lot.

My own inclination would be to take the ballcock valve apart and look for slack in the moving parts but you may not want to bother if it's not your house.