Solution to inaccessible Isolation valve rubber

[Erico19]

Hi,
My toilet tank pipe seats eactly above a straight isolation valve; it is leaking from its top. I believe it is due to the valve's rubber which I found in a bad state.
The main water supply valve is jammed; I don't want to force it. I was hoping to be able to lift the toilet water tank but I could not.
Can I cut a rubber to slide it through the pipe? Will it work? Is there a better solution? Thank you

 

[ShaunCorbs]

New fibre washer required but your going to have to turn the water off so sounds like a plumber is required to sort the main stop tap out first

 

[Deleted member 120897]

Sorry, I can’t really make sense of what you’re asking. Are you able to post a photo of the cistern?

 

[Erico19]

Sorry, I can’t really make sense of what you’re asking. Are you able to post a photo of the cistern?

 

[Deleted member 120897]

Yeah, as per Shaun, new fibre washer required. Is there any wriggle room in the pipe? Alternatively you could (if the cistern is fully empty), undo the plastic backnut, lift the inlet valve slightly and replace the washer - be careful with this method though, susceptible to cross threading.

 

[Erico19]

Yeah, as per Shaun, new fibre washer required. Is there any wriggle room in the pipe? Alternatively you could (if the cistern is fully empty), undo the plastic backnut, lift the inlet valve slightly and replace the washer - be careful with this method though, susceptible to cross threading.

Many thanks for all your responses. I unscrewed the toilet cistern, I tried gently to detach it from the toilet seat but I was no successful. However, this video

shows that the toilet cistern is detachable. I wonder will there be any damage if I remove it? Or should I try to lift it slightly just to insert the washer?Thank you

 

[Deleted member 120897]

Seems a bit dramatic to remove the cistern for a fibre washer.

 

[ShaunCorbs]

Undo the screws that hold the toilet and cistern to the wall and floor on that side and tilt the toilet