How to undo stuck float valve assembly in toilet cistern All aspects of plumbing questions and answers, help, tips and information

[flyingcarp]

I'm trying to replace the diaphragm in my toilet cistern float valve, to fix a 'foghorn' sound. But I can't unscrew the part to get to the diaphragm. It's pretty close to the corner of the cistern so I can't get any tools in there (see photo), but I've managed to apply a fair bit of force by hand and it's not budged. Tried spraying a bit of WD40 up into the thread, but still stuck.

Does anyone have any suggestions? Replacing the entire float valve would be very inconvenient as it's a bottom inlet type and the bottom of the cistern is behind panelling with no access.

[stoneyboy]

Hi flyingcarp,
You should be able to get an an adjustable wrench on the nut by tilting the wrench at an angle but you must stop the vertical shaft from rotating gripping it with another wrench. If you don’t grip the shaft you will undo the bottom connection.
Regards S

[flyingcarp]

Thanks stoneyboy. I'll give it a go but my feeling was the wrench "teeth" won't reach the ring because of the top and the fill tube sticking out the side. Is there such a thing as a "long-nosed" wrench that could grip around these obstacles, I wonder?

[stoneyboy]

Hi flyingcarp,
Suggest you search for Kennedy water pump pliers or something similar. They should give you enough grip in the space available.
Regards S

[flyingcarp]

Thank you very much stoneyboy! I bought some long pliers, managed to get it undone and have replaced the diaphragm. Very happy!

[stoneyboy]

Hi flyingcarp,
Thanks for letting us know - happy flushing!
Regards S