New sink straight through trap

[rshort1987]

Hi
I discovered my sink was leaking from the trap and bought a new one today. I have put in the new one but it still leaks from the top and is wobbly. The one I took off was covered in putty stuff (plumbers mait?) Will I need to reapply this to get the pipe to stay in place and seal?
Thanks

 

[oldbuffer]

Its not clear to me what you have replaced.

1. If its just the trap, then it shouldn't have had any plumber's mait on it, suggesting there is a fault with the waste. Replace the waste.

2. If you have replaced the waste fitting, they normally come with two washers. A "foam" washer (usually white) which goes between the top lip of the waste and the top side of the sink. A rubber washer (usually black) which fits under the sink. The foam washers are usually pretty poor. I normally discard them, roll a "sausage" (more like a chipolata) of plumber's mait and use that instead. Assemble waste into sink with black rubber washer under sink, plumber's mait between waste lip and upper side of sink. Tighten waste, remove excess plumber's mait, repeat a couple of times. Scrape of any excess plumber's mait, and use kitchen roll and white spirit to remove any remaining spots. Refit trap.

 

[rshort1987]

Hi, thanks for your reply
This is the part I bought today and where the water is coming from

It tightens up fine but the pipe is then wobbly and I guess the reason for the problem. Is point 2 what you think would work?

 

[oldbuffer]

You have replaced the trap.

Is this under a wash basin rather than a sink? Because if so, quite often there is not enough thread on the bottom of the waste fitting to enable the trap top nut to be screwed far enough up to seal its rubber washer against the bottom of the waste fitting. Often, part of the "pop up" mechanism gets in the way. Two ways round it:

1. Get another washer or two to go inside the top nut of the trap (the arrowed one in your diagram).
2. If you've got a very steady hand, cut the first two threads off the top nut. You need to be very careful not to damage any of the remaining threads.

Good luck.

 

[rshort1987]

Thanks. Yes it is a wash basin.
I have tried method 1, using the old trap washer. I switched the washers round so the new one was on top, presumably creating the seal. Not sure if this would make a difference. However, the trap is now a lot more sturdy. The drip is less but still there, it gradually reduced as I've managed to get the nut tighter. It is now very minimal. Would this suggest that I just need to keep tightening it as much as I can. Would anything else help.

The thread of the waste fitting has a lot of the putty type stuff i mentioned before still around the top. Would it help to try remove this as much as I can?

Thanks so much, its been a stressful day!

 

[oldbuffer]

If the sealant is only at the top of the threaded part of the waste it has probably been put there to stop the overflow leaking down the threads of the waste. Leave it alone.

If the sealant is at the bottom of the threaded part of the waste, it may be interfering with the seal between trap and waste and should be carefully removed.

If the sealant is soft, like unhardened putty, its likely to be plumber's mait. If its more solid but rubbery its probably silicone sealant.

Try and get another washer for the trap, sounds as if it might do the trick. Or better, use two additional new ones and throw the old one away. Toolstation 99131 looks as if it should do the trick.

 

[Madrab]

Is the top threaded nut (above your arrow) tight up against the bottom of the sink/end of thread? As old buffer suggests, there's probably not enough waste thread to tighten the seal up to the bottom edge of the waste.

Either fit a new waste that's long enough or cut the plastic nut at the top by 2-3mm with a hacksaw, taking your time. Anything else is only really only going to be a bodge at best and will eventually leak IMO.

Oh, a thought, is the centre leading edge of the trap's pipe (that the seal sits over) actually fitting into the waste hole, had a few wastes that really needed the trap to be pushed tight up into it.