Toilet cistern slow leak

[KennyPowers]

We have a little puddle forming between the toilet seat hinge area, and bottom of cistern. I suspect it maybe the gasket seal between cistern and pan.

I removed the internal dual flush tube mechanism thingy from inside the cistern, and checked the seals there. Didn't seem too bad, cleaned them up, and put the mech back in the cistern. I did measure the hole with the mech out, and it was somewhere between 2 to 2.5 inches. Also noticed the black seal diaphragm thing in the mech was dripping what seems like black ink from it, which I found odd.

Anyway, put all the cistern back together, and it is still leaking. I will order a spare seal for between the cistern and pan, but don't want to remove the cistern until I have that bit ready to replace it.

What seal etc should I order from Screwfix then?

Thanks.

 

[foxhole]

Does it leak all the time or only after a flush?

 

[jeff the gasman]

You’ll need to remove the cistern and fit a new Donut washer between the pan and cistern.
Check tightness of flush valve at the same time.

 

[jeff the gasman]

Looking at the pictures you’re already over your capabilities on this!

 

[Sonic70]

Check the two bolts either side of the mechanism as well. My cistern was leaking from one of these bolts. I had to take the cistern off to tighten the nut on the other side.

 

[jeff the gasman]

Get one of these.

Viva Close Coupled Doughnut Foam Washer 2″ Outlet PP0035

Replacement donut washer for close coupled WC suites with 2" outlet valvesManufactured by Viva Sanitary…

plumbinbits.co.uk

 

[KennyPowers]

It's not the 2 bolts as I changed these a few years ago when they had corroded, and actually was leaking from them.

I think it must be the seal that Jeff mentions, because even if the seals in the mechanism are dodgy, the donut seal should still stop any water from getting outside the cistern?

Looked on Screwfix for seal similar to what Jeff linked, and found this one. But looks a bit different shape, and comes with a bracket? https://www.screwfix.com/p/wc-close-coupling-kit-white/84958

 

[KennyPowers]

Does it leak all the time or only after a flush?

After checking, it seems to constantly form a puddle regardless of whether I've just flushed or not.

Perhaps it could be from the 2 bolts either side of mech. Last time it was obvious as water was on the thread near the wing nuts, but maybe this time it doesn't get that far because of the big rubber washer on the bolts I fitted?

 

[terryplumb]

The seal on the base of the flush valve ( in your earlier pics) is not sealing against the inside of the cistern. You have removed the valve and the nut that secures the valve to the cistern ,thus compressing said seal ,can't be tightened up without removing cistern from pan ,which you aparrently have not done.
The seal itself doesn't look to be in good condition ,and should be replaced.

 

[KennyPowers]

Agree the valve in earlier pics doesn't look great, but if the leak was there, wouldn't it be a constant trickle inside the toilet pan, not outside the cistern? (If my understanding is correct)

The part about not being able to tighten without removing cistern from pan, is this regarding the donut seal?

Not sure what my next step should be, it is looking like removing cistern from pan and taking a look then. I'll get some plumbers mate from SF ready just in case then.

 

[Madrab]

Unfortunately you shouldn't be removing the basket base section of the flush valve from inside the toilet, there is a big plastic nut that sits on the bottom outside of the cistern, surrounded by the doughnut washer, that nut needs to be held tight so the flush valve basket (pic4) can be tightened down properly and sealed correctly. As suggested, that can only be done properly with the cistern off the pan.

If that basket section could be removed by just twisting from the inside, I'd suggest it wasn't tight enough in the first place and could be why it was leaking past the seal. Again as suggested, the rubber seal doesn't look the best, possibly overtightened, may need replaced though sometimes they can be turned around and re-tried. Make sure everything is dry and clean before refitting.

To do all of this the cistern need removed off the pan, at that time you will see what type of doughnut you'll need, there are several types which can't really be identified until the cistern is lifted. That'll also give the opperchancity to check the securing bolts and rubber seals, a little silicone would seal them back up if removed and refitted.

 

[KennyPowers]

Thanks guys, I got a better picture of what I'm looking at now in my head.

Will remove cistern from pan when I get an empty house, and have some silicone/plumbers mait at the ready.

(I got the idea to remove the flush valve from inside cistern from this YouTube video, but didn't consider a plastic nut the other side)

 

[Madrab]

Well that's says it all, it was done so well when done previously that it now needs done again. Once those flush valves are fitted they shouldn't really ever leak past the main seal again. That's why they have a bayonet fitting, so just the drop valve, which is the part that would usually wear, can be serviced for inside the cistern without having to take it off the toilet.

 

[KennyPowers]

Just finished removal of cistern, tightening the loose nuts, cleaning seals/surfaces and applying some plumbers mate, and reassembling.

So far, no more leakage. I did have some trouble with the inlet valve not shutting off, but this was due to the float fouling on the cistern wall. Slightly rotated the mech, and now the float is clear to float up.

Measured the seal whilst I had it all out in case I need to order replacement in future.

 

[terryplumb]

Can't view pics ,post directly onto this site.
Glad your sorted.