there is a continual dripping sound in the cistern with water dripping into the toilet. I was told to replace the ballcock valve but the inlet valve is an old one and I'm not sure how to undo the top of it to replace the valve.

david, January 2010

There is a few different types of washer for different valves. In my experience dont go for a cheap new plastic valve assembly. I did, and the whole thing split causing a lot of water to come through. More than the overflow could cope with. Fortunately I was at home at the time. Good idea to set the water pressure to what your overflow can cope with.

Jonathan, December 2010

If its the one I think it is then the brass arm is held in place by a brass spit pin obviously at the valve end. First turn off the water feed to the cistern and flush the cistern so you are working in an empty cistern.
The valve housing has a knurled cap at the float arm end and this needs to be unscrewed. Once this is off you will see the end of the valve barrel. Work the float arm up and down gently to its full extent a few time to ease removal of the valve/washer barrel.
Remove the split pin holding the float arm to the valve housing and work the arm out of the valve slot hopefully at this point pushing down you will have pushed the valve partly out. remove the arm and pull the valve out take this to a plumbing shop and ask for a new one same type. You may have to buy the whole unit as I have not see anywhere that sells just the valve. If you do get one then vaselene the barrel to ease movement and help protect against lime build up.
The following refers to copper pipework talk to plumbing shop if plastic. problems arise if the feed is the old lead pipework.

Failing carrying out the above remove the whole unit and replace with the new plastic type which are easier to work on to replace washers.
You may have to shift extend pipe work on replacing the the whole valve asssembly but push fit [releasable types] are as good if not better than compression fittings and if no separate water stop cock to cistern now would be the time to fit a check valve. also the chrome braded flexi joints are a god send to replace pipe work. cut the pipe where require [copper] clean end with wire wool add a stopvalve pushfit plastic one.
then a short length of copper in the end to take the flexi fit push fit joint it's easy don't be put off by this. Draw it mark off what's going where and away you go i've done it that way and still do. Draw first work after. Safety point regarding children. Don't let them play with push fit joints becuase if there inquisitive fingers get stuck plumbers can't remove firemen or hospitals can.:-


Hope this helps

Bob, February 2010