Sealing off isolation valve

[Erico19]

Hi,
The isolation valve feeding my toilet cistern was leaking. After considerable effort, I was able to lift up the cistern to put an O-ring washer around the top of the inner circle referred to with an arrow in the attached image. Unfortunately, when I let the water through, there was a burst leak. Should I use a flat-ring washer instead? If so how can I get the right size?Should I put the ring at the top or push it down?
A friend suggested using also a jointing compound along with a PTFE tape; If a washer is enough, I won't buy these products

Thank you.

 

[ShaunCorbs]

1/2 fibre washer or a 15mm hep2 o flat washer

 

[Erico19]

Thank you, Shaun.
For the flat washer, would a rubber washer be sufficient or does it have to be a steel washer?
I take it, there is no need to use a jointing compound and/or PTFE tape, right?

 

[ShaunCorbs]

Rubber or fibre

No not steel

No doesn’t need any paste ptfe or anything

 

[Erico19]

Rubber or fibre

No not steel

No doesn’t need any paste ptfe or anything

Thank you for the confirmation, I'll let you know the outcome

 

[Erico19]

Hi,
I got the 1/2' Fibre washer today, place it as you can see in the attached images. Unfortunately, still the water leaked out. Any advice, please?

 

[adonis]

I find sometimes if you put 2 fibre washers on the fitting it can work.

 

[Basher]

The mating metal surfaces that compress the fibre washer need to be clean and smooth and damage free.
Surprised it didn't seal! Did you do up the nut tightly (but not so tight as to damage the plastic thread)?

 

[ShaunCorbs]

Prob a bit loose it’s hard to guage with plastic threads best would be to tighten up then turn the water on and tighten slowly until no water is leaking

 

[Erico19]

The mating metal surfaces that compress the fibre washer need to be clean and smooth and damage free.
Surprised it didn't seal! Did you do up the nut tightly (but not so tight as to damage the plastic thread)?

Thanks for your reply. I just put the washer without any cleaning...I upped the nut nicely and smoothly to align with the plastic threads.
I wonder if I have to put a bigger washer to fit inside the nut instead of putting a 1/2" washer at the top of the inner circle of the isolation valve? Should I use a jointing compound along with a PTFE tape?
Cheers

 

[Erico19]

Prob a bit loose it’s hard to guage with plastic threads best would be to tighten up then turn the water on and tighten slowly until no water is leaking

Thank you; I'll give it a try tomorrow...

 

[Erico19]

I find sometimes if you put 2 fibre washers on the fitting it can work.

I find sometimes if you put 2 fibre washers on the fitting it can work.

I'll give it a try. I bought two fibre washers. Despite the excellent specification; the thickness of the washers I received is 1 mm only.

 

[Erico19]

I looked at it again this morning, using PTFE tape and Jointing compound, I kept one Fibre washer as there was not much space for two....Thankfully, the water did not leak out from the joint when I tested it. Many thanks to all of you for your help

 

[Erico19]

I looked at it again this morning, using PTFE tape and Jointing compound, I kept one Fibre washer as there was not much space for two....Thankfully, the water did not leak out from the joint when I tested it. Many thanks to all of you for your help

Me again...sorry.
If the isolation valve leak is fixed, I am getting now a leak from the plastric nut at the bottom of the fill valve...I checked the nut; it is tightly adjusted. May be it got a bit misaligned as I kept removing and putting back the toilet cistern...any advice please? Thank you

 

[ShaunCorbs]

The nut against the cistern ?

 

[Erico19]

The nut against the cistern ?

outside and at the bottom of the cistern,see please the top arrow in the attached image, leading to the external isolation valve

 

[ShaunCorbs]

Need to remove it all to find out why it’s leaking might be not centred etc

 

[Erico19]

Need to remove it all to find out why it’s leaking might be not centred etc

Thank you, I'll give it a go

 

[Erico19]

Need to remove it all to find out why it’s leaking might be not centred etc

I did not screw the cistern on the wall or on the toilet seat when letting the water through; doubt this could be a cause. Here is the picture of the inside, an O-rubber seems at the bottom of the valve. The nut seems too tightly adjusted.