toilet flush - seals OK, then trickles, even with new washer Featured

I think you need to adjust the float valve setting and lower the water level in the cistern. As your overflow is leaking into the pan inside the cistern should be a vertical tube if the water level tops this tube water will continue to trickle into the pan once the cistern has filled. If the it stops after a while it is probably right on the cusp but will get worse.

Modern cisterns are required to have a maximum flush of 6L and there is usually a line marked at the back to enable correct adjustment. It is a matter of trial and error adjusting the float valve.

Richard

Thanks, but I'm not convinced... There is no overflow occurring AFAICT, and the settings on the flush and fill valves are unchanged over many years.

J^n

Scale or grit on the seat or cylinder that the valve moves in. Alternatively, if the thing had been leaking for a long time with the old seal, maybe the seat has been damaged.

In many cases it can be easier to find a generic replacement and swap it out. They are usually pretty cheap these days.

Is this the "standard" system where the flush lever starts a siphon which runs until the cistern is empty or a flashier system that opens a valve between cistern and pan?

nib

I assume the washer is one of the large, 60 mm or so, diameter ones.

Some tend to form ‘bubbles’ on the surface. These stop the washer sealing. While I’ve not tried it, I saw a video on YouTube which showed someone popping these and forcing the water out, before refitting the washer.

I’ve always replaced the washers, the faff involved for the sake of the minor expense, isn’t worth it if it needs taking it apart again- I find refitting the buttons a pain on ours.

Hi John does the 'genericity' extend to the new flush valve likely being able to fit into the old base? IIUC fitting a different base would involve a degree of dismantling on the WC.

Thanks, J^n

IME The "trickle" that is happening is usually only possible on the more modern valve type rather than the syphon type.

If it is "close coupled" setup, then normally I would drain the cistern, and undo the connecting bolts to remove the cistern from the pan. Then remove the valve and replace. They normally have good conical washers to seal against the hole in the cistern (a bit of silicone grease will help seal and also aid doing it up tight). Then fit a new doughnut washer (bit more silicone grease), place the cistern back on the pan and do up the connecting bolts. Usually a fairly quick and easy job so long as you can get the pan to cistern fixings undone.

Hi John Thanks for that, I wasn't sure of the details. I guess I am still reluctant to go this route, since I have not convinced myself that it is the flush valve itself at fault. If I have changed the washer, and the mating surface seems OK, I am not sure what the fault might be. Still, it might come to pass...

J^n

This is simple stuff and there aren't a lot of things that can go wrong. If you're certain that: the seat and washer are OK, that the washer is correctly fitted, that the flush valve isn't sticking, that the seal at the bottom of the flush valve is OK, and that the cistern hasn't cracked ... either give up or replace the flush valve. There's one thing I would add to John's description: it can be difficult to get the inlet pipe to seal on older bottom-mounted fill valves. The trick is to loosen the fill valve's mounting to the cistern, connect the pipe, and then tighten the fill valve's attachment. This allows things to line-up.

and another tangentially related tip, I notice that when buying modern fill valves you can get the standard version for say £12, and the version with a brass thread instead of plastic for whopping 80p more :-)

(go brass every time!)

Delayed update ... I seem to have fixed the matter...

The washer for this model (Roca Dual Flush) is attached to the flush valve by a (plastic, cheap) flanged washer, whose lock arrangement was difficult to determine. It's not got a thread, but a sort of clip arrangement.

It looks like I did not fully fasten this in the 'approved' manner; as a result, the washer was a tiny bit loose in the 'lateral' direction. I think this was allowing it to 'bow', when the seal was made, and sometimes during the fill cycle, this allowed a trickle of water through.

Having worked out that you should both 'click' the washer down, and then give it a quarter turn, and even though the appearance is basically the same, things have been fine for a week. So I'm pleased I didn't give up...

Thanks for the various hints & pointers

J^n