leaking brass transition to abs trap

[mj]

I've tried fruitlessly to stop a leaking brass-to-ABS transition in my new bathtub's drain. The tub drain itself is brand-new 1 1/2" brass male end on the horizontal. The brass drain is connected to a new, threaded female ABS 90 by means of a compression nut with washer. The leak seems to come from this transition, with water dripping from the nut.

I've tried several types of compression nuts and plastic washers to try to stop the leak without success. Someone told me that a neoprene washer under the plastic compression nut or plumber's putty might stop the leak. This seemed like a sort of band-aid approach to me and because the tub is huge, cast iron, and about to be buried in tile, I'm not keen to try anything again without getting some more advice. Is there a particular type of washer/nut recommended for this type of transition?

THANKS,

Aching back

[TedL]

Have you carefully checked the surface of the ABS fitting to make sure there's no irregulaties (like nibs that weren't removed), and the brass tubular for irregularities or out of round?

[hj]

ABS compression joints do not take rubber gaskets very well. You need the plastic poly washer that is tapered, but how/why is it connecting to an elbow? it would normally be to a trap or tee.

[Norcal]

Make sure the plastic washer is installed correctly...I see lots of these installed backwards.

The flat side of the washer should be up against the nut.

[mj]

Hi and thanks for replies...

The tapered plastic poly gasket is installed correctly in the nut and all surfaces are smooth and round. The elbow I mentioned is the first part of the trap.

If I put this joint back using a plastic gasket/compression nut, should I maybe also line the inside of the nut with putty? If this stops the leak, will the putty solution last?

Is there anything else I can try?

[hj]

I would also check the thread where the brass is screwed into your drain's tee. THAT is more likely to be the source of the leak, especially if you did not use a good thread sealant when you assembled it.