Cistern drip

Hello all, Can anyone advise on a cistern that has a slow drip please?
I've only just replaced the whole cistern unit. The drip comes through the thread of the pipe sticking out of the bottom (actually it's all one piece with the internal mechanism. It was also leaking directly under the cistern untill I put some evo-stick on there - so its a bit better.
A previous post recomended Fernox Leak Sealant - is this the right stuff? The evo-stick was recomended by my local plumbers merchant. I also have some PVC glue.
(By the way the unit also had a leak at the join with the inlet pipe, due to nut not threading properly. I managed to cure this by cutting the pipe down a bit to remove a section with wonky thread, but is all this kind of thing a common problem wth plastic joints?)
Anyhow thanks for any help, Ad
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By cutting the pipe you will have inevitably ruined the seating face of the threaded section. Get new ball valve.
--


Regards

John


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Presumably you mean Evo-Stick 'Plumber's Mait'?

Like the man says you probably have a leak where the cut end of the threaded section tries to join to the connector on the pipework feeding it. Cross-threading and thus mangling the threads is a hazard with plastic inlet valves: the trick is to leave the valve screwed only loosely into the cistern until you've screwed the connector nut a few turns onto the thread by hand so you know it's on straight. What you might do if you have sufficient length of pipework feeding the cistern valve is cut it and use a Speedfit tap connector like http://www.screwfix.com/app/sfd/sea/searchresults.jsp?n 720 which has a rubber rather than fibre sealing washer (which may take up the irregularities in the cut end of your thread) and can (and must) be entirely tightened by hand (so you don't ruin the thread on the valve again). You could put a service valve (like http://www.screwfix.com/app/sfd/sea/searchresults.jsp?n 483 or http://www.screwfix.com/app/sfd/sea/searchresults.jsp?n 372) in the pipe while you're at it.
-- John Stumbles -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -+
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It is common with bad practise from lack of experience of how to make good plumbing joints ,be they soldered or compression,lack of the correct tools in diy circumstance is also a facter to consider
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Thanks Alex & John. But, Erm, the pipe I cut back a bit (water inlet) cured the leak on that one. The one i didn't cut (underneath, delivers flush to pan) is the one with the leak. This leaky one just has a has a plastic screw ring that you're supposed to tighten to make water-tight - only it ain't.
Suppose i'll try some of the sealers in my 1st post, & if doesn't work take the cistern back to Plumb centre for another.
Cheers Ad
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I have just fitted a new bottom inlet valve (Fluidmaster) - it came with a squidgy rubber washer. It doesn't leak! Have you got a washer?
--


Regards

John


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Did you place the large rubber washer inside or outside the cistern,if out it should be in..Failure to tighten the backnut correctley often cuases leaks at this joint.A smear of silicone between washer and syphon and washer and cistern should solve your problem.Cleanliness and drying the area is also very important.
I change these at least 5 or 6 times a month fitted correctley they do not leak
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Most plastic fittings recommend you don't use any form of additional sealant on the joints; some sealants will attack and weaken the plastic. If the cistern is leaking from the bottom, check the rubber washer (normally fitted inside, not outside), also the nut shouldn't be too tight, if it is, it can crack the plastic; it needs to be just tight enough to seal; if it requires anything more than hand-tight, there's something wrong.
I may well get flamed for this, but, I often use a (very) small amount of Vaseline on plastic fittings where there is a compressed rubber washer, it helps with sealing and also makes it easier to remove should you have to in the future.
HTH
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John, yes it does have a washer. Maybe part of the problem is that the whole internal mechanism leans a bit when handle is pulled - you can see the bottom of the (plastic) cistern "wobble",maybe it opens it up enough to leak a bit. The flush pipe wiggles too.
Alex, yes I did put the washer on the inside. I've put some silicone sealer on now - mostly on outside as can't get decent acess inside without taking it all off the wall and apart. I let it dry for about five hours, then released the ballcock arm to put the water back on and seems ok so far.
Grunthos, yes i might have overtightened it. (why don't they say in the instructions - obviously i'm not a professional).
I think in future it might be better to assemble it as far as possible, including the flush pipe, before fixing it to the wall, whiile it is easy to fiddle with.
Thanks all, Ad
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