Toilet Fill valve washers

shiraz99

I've got this troublesome fill valve, well the actual connection with the inlet where it weeps. I'm going to be changing the fill valve for a new, brass threaded, one and i just wanted to check the type of washer i need on the inlet. I'm currently using 1/2 inch fibre tap washers, even followed advice to double up but still get the occasional weep so was thinking maybe a 1/2 inch rubber washer might work. What do you think?

FreeBear

For troublesome seals, I'll often put a thin smear of silicone sealant around the hole. Just needs to be enough to fill the irregularities of the surface without drowning the washer.

CliveOfIndia

Looks to me as though the inlet is not flush (excuse the pun!) with the cistern.  Is there any "give" in the pipe that would allow you to move it ever-so slightly so that it sits square against the cistern (obviously be gentle, you don't want to go causing a leak elsewhere)?  Failing that, then a little dab of silicone should do the trick, as suggested by FreeBear.

Whilst you've got it dismantled, take a few minutes to give everything a really good clean (threads, pipes, mating surfaces etc.).  It's always a good idea when you're doing any sort of plumbing - it's surprising how a relatively small bit of grit or muck can stop you getting a good seal.  It only takes a couple of minutes, a damp cloth and plain water is all that's needed, and an old toothbrush is handy for giving any threaded parts a clean.

shiraz99

Just to be clear the leak is coming from the connection to the inlet, it's weeping from below the nut, rather than the back nut against the cistern which is perfectly dry. I agree it does look it isn't sitting square but the tail does sit flush with the inlet connection.

nofoollikeold

1. The back-nut attaching the threaded shank to the cistern (white plastic nut) is cross threaded.  I'd replace it with a 1/2" BSP brass back-nut.  E.g. Screwfix 66268
2. The water seal for the shank is made by a black rubber washer between the flange on the inside of the shank and the base of the cistern.  
3. I appreciate you are adamant the leak is at the lower nut.  However, I would be very surprised if the leak is not from the cistern running down the threads of the shank and appearing at the connector nut.  
4. As suggested above, give everything a good clean while dismantled.
5. The seal between the inlet pipe and the threaded shank is normally a 1/2" fibre washer between the base of the shank and a flange on the tap connector.  The connector is the brass item at the top of the copper pipe.  Make sure all remnants of any old washer are removed before fitting a new one.  
6. Some newer shanks are designed for use with an olive.  These shanks have quite sharp chamfered edges, rather than flat edges, and can cut fibre washers if done up too tight.  If yours requires an olive, you will also have to change the tap connector.