Leaking toilet from base of cistern only when flushed

[LarryN]

Hi all. I've a toilet that is leaking from the base of the cistern only when it is flushed. Most of the water runs down the nuts and onto the floor. Most of what I've read suggests that it should be a case of taking off the cistern and replacing the rubber washer between the cistern and bowl. Would people more experienced that me recommend this. I'm guessing there is no way of fixing without removing the cistern? Thanks.

 

[denso13]

I'm guessing there is no way of fixing without removing the cistern?

Unfortunately not, that's the first step in finding out what is wrong and what type of donut washer you need.

 

[LarryN]

I didn't think so. Thought I'd check though.

 

[CarloHeatingEng]

You've got it right. Leak only on flush, running down the bolts, is the doughnut washer between cistern and pan, not the fill valve. It has to come off, you can't reseat it in place.


Not as straightforward as it reads though. Bolts are often seized and china cracks easily, so go steady and don't overtighten on the way back. If you're not confident, get a plumber to it, it's a quick job for someone who's done a few.


Main thing is matching the doughnut exactly. They vary between makes and a near-enough one will leak again, so take the old one with you.

 

[LarryN]

You've got it right. Leak only on flush, running down the bolts, is the doughnut washer between cistern and pan, not the fill valve. It has to come off, you can't reseat it in place.


Not as straightforward as it reads though. Bolts are often seized and china cracks easily, so go steady and don't overtighten on the way back. If you're not confident, get a plumber to it, it's a quick job for someone who's done a few.


Main thing is matching the doughnut exactly. They vary between makes and a near-enough one will leak again, so take the old one with you.

I've got the cistern off ok and took the heavily flattened donut with me to the plumbing spares place, but we couldn't work out whether it was a 1.5" or 2", so I got both. I squeezed (and it was a squeeze) the 1.5" over the hexagonal fitting on the base of the cistern and reconnected it all, but on first flush it still looked like it was leaking and I've run out of time this morning. I don't need to add any sealant or anything do I? The donut should handle any excess. I'm planning on taking apart again. It might be that it needs the bigger donut.

 

[CarloHeatingEng]

Sounds like the wrong washer. The right one seats without a fight, and it'll seal with a sensible nip up. If you're having to squeeze it over the fitting it's telling you something.


No sealant. The doughnut is the seal. If it needs silicone to stop it, that's the washer being wrong rather than the joint needing help.


Try the 2" before you do anything else. And the merchants should have been able to identify it off the old one, that's what they're there for.