Leaking connection between plastic thread and copper pipe

[Jim1982]

Hello all, I noticed earlier in the week that there was a slow leak below my toilet cistern at the point where the copper pipe meets the plastic thread via a nut.

I have used some toilet paper to locate the source of the leak and its coming from the top of the nut.
Somewhat suspicious that there were globs of sealant / plumbers mait around this nut i.e. there were obviously some problems during installation at this point, as theres no evidence of this on the other toilets in the house (3 yr old Barratt home)

I've taken the pipe apart, wrapped PTFE tape around the plastic threads, replaced the fiber washer that was being used with a new 1/2 inch fiber one, but the leak is still persisting.
I'm not sure what to try next and would really appreciate any advice that more experienced people could give me, I just need to get a good seal at the top of this particular nut.
I have taken some images of it to make it clearer (hopefully)

Plastic thread at bottom of cistern

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• Jim1982
• 31 Mar 2009
• 1

Copper water pipe

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• Jim1982
• 31 Mar 2009
• 1

Copper water pipe with fiber washer replaced

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• Jim1982
• 31 Mar 2009
• 1

Pipe and thread connected (with nut not done up)

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• Jim1982
• 31 Mar 2009
• 1

Pipe and plastic thread connected, nut done up. Red arrow indicates leak point

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• Jim1982
• 31 Mar 2009
• 1

 

[seco services]

its quite poss the leak is coming from the plastic thread.
people over tighten the nut on the thread and stretch them and they split between the threads.

if it is the case then a new float valve.

 

[namsag]

As seco says,
Catches you first few times you see it

 

[seco services]

As seco says,
Catches you first few times you see it

make ya right there.

 

[Jim1982]

Thanks for the replies. Replacing the float valve is my backup plan, bought a kit to do that today.

I was just reluctant to take the thing apart if not necessary, due to my plumbing inexperience.

Looks like it will have to be done though.

I assume from the above posts then that the nut should not be done up too tight, to avoid damage to the plastic threads.

 

[seco services]

i useally hand tighten then just nip up 1/4 turn with spanner. then open you isolation valve slow see how it go's if it weeps just give it a nip up.

 

[Paul Barker]

i find the hepworth tap connector suits plastic threads best. it has a cone shaped rubber seal which seals poor mould finished plastic carp.

 

[seco services]

i find the hepworth tap connector suits plastic threads best. it has a cone shaped rubber seal which seals poor mould finished plastic carp.

yes they are a quick and easy solution to toilet valves

 

[Jim1982]

Tomorrow I'll have a go at replacing the float valve and see if that sorts it out.
Otherwise then it seems Hepworth connector may be worth a go.

Whatever sealant was applied during installation has obviously held the leak in check for about 3 years, its just suddenly started recently with no apparent reason.

 

[seco services]

thought you was doing it now.

you can have it changed by the time news at 10 starts.

 

[Jim1982]

I've had enough for the night now. A hard day at work followed by some frustrating leak hunting and failed attempts to fix is enough for one evening.
Time for a beer and a break.

I'll attack it again tomorrow, closing the valve keeps it under control. (touch wood)

haha, you overestimate my basic plumbing skills

 

[seco services]

make sure you sleep well
you got plumbing jobs to do tomorrow.

see you back here tomorrow then.

 

[johnfox]

my pennys worth.
use a new washer.
ensure copper pipe is straight and putting no strain on plastic ball valve tail.
ensure plastic ball valve tail thread is not damaged.
ensure mateing surface on plastic ball valve tail (where fiber washer) touches plastis is 100% flat.
use some ptfe tape between fiber washer and plastic,make a gasket.
yes i have been in this situation before.one diy job turns into several more.
good luck.

 

[seco services]

use some ptfe tape between fiber washer and plastic,make a gasket.

what do you think the fibre washers for ?

 

[johnfox]

yes i know fiber washer is to seal the join.but has any one ever used ptfe on a compression type join before.me thinks yes.