Leaking concealed cistern from the flush mechanism hole - advice please.

[manicminer]

Hi all,

I've been DIY fitting a new concealed cistern toilet in my downstairs cloakroom for the last couple of weeks (in evenings etc.). I've finally got it install installed and leak free apart from one joint 🙁.

The leak is coming from where the thread of the flushing mechanism passes through the hole in the bottom of the cistern. The the bottom of the cistern is not completely flat (molding marks) and the washer for the outside of the joint is very solid plastic, I'd expected something more flexible / rubber. I originally had a leak from the thread but a single turn of PTFE tape has sorted that, but I've still got leaking at the very top of the joint stack, because it isn't sealing against the cistern itself.

Any advice, the instructions say not to use sealants etc. on the plastic parts, I was tempted to use silicon and then do the joint up and let it all set, but I don't to cause more problems with the silicon damaging the plastic cistern or the pipework / nuts.

It's a homebase "buxton" system if that is of any help.

Any advice welcome, I'm beginning to dispair

 

[ne1ls0n]

should have been a flat rubber washer in there somewhere mate, sort of thimg your local plumbing merchants would be happy to supply. or silicone it

 

[darren-]

There should be a thin rubber washer on the inside of the cistern then a plastic one on the outside before the nut goes on.

 

[Guest123]

Sanitary silicones won't damage the plastic cistern. It's linseed based sealants like putty and boss white that damage plastic.

 

[manicminer]

Thanks for the heads up, I thought silicon should be fine but didn't want to cause more problems!

Darren, this is a concealed cistern, I think you are talking about a close coupled one with the rubber doughnut?

This is a drip leak all the time when there is water in the cistern, at least it means I can turn the water off and flush to prevent it leaking too much!

 

[darren-]

I edited it after I wrote it mate, typing and watching Barca

 

[PlumbBobBob]

as said there should be a rubber washer inside the cistern between the flush valve and cistern to make the seal

 

[manicminer]

as said there should be a rubber washer inside the cistern between the flush valve and cistern to make the seal

I'll dismantle it all and double check before using any silicon.

Thanks for clarifying.

 

[manicminer]

I'll dismantle it all and double check before using any silicon.

Thanks for clarifying.

OK. So having dismantled it there is a huge rubber washer on the inside, no idea why it was leaking. Pulled it all apart and reseated it. Currently on the sink full of water testing for leaks before plumbing back in. So far no leaking 🙂

Thank you all for the info and advice.

 

[PlumbBobBob]

could be just wasn't tightened up enough