pipe thread leak question dishwahser followup

I'm finishing up my dishwasher replumbing. To get from my 1/2" PB to those connection hoses I had to use a plastic fitting that just pushed onto the PB. Looks cheap, complicated and leak prone but amazingly worked w/o a hitch. Of course that isn't all. That took me from 1/2" PB to 1/2" pipe. Then I had to screw on a brass fitting to go from 1/2" pipe to 3/8 compression which the supply hose connects to. This joint leaks despite using 5 or 6 turns of teflon tape on the threads. It's not a big leak just the formation of a water drop under the fitting that never seems to drip off but that's still a leak. I'll take it apart and try more teflon tape but how many turns should you use to seal a pipe fitting? I'd say I have the problem with 50% of the pipe joints I make. Air, water, oil etc.

As for how things worked out. I got a supply hose made for dishwashers that is like those hose type risers used under the sink that seal with rubber gaskets instead of the compression fitting. Those hoses have always worked nicely everywhere I have used them. I wanted something that could be removed, reinstalled or replced easily if needed in the future instead of the PB install I had which had to be cut loose when it got kinked trying to get the dishwasher out far enough to fix the busted drain hose.

I replaced the corrigated hard plastic drain hose with a rubber hose called heater hose that was sold at Lowes. I ran it in the bottom of the cabinets over to the sink drian then went up to the top of the sink cabinet and down to the drain fitting. The old hose made a high loop on the side of the dishwasher before running under the cabinets to the drain. It seems to work and I guess that's what counts.

Thanks for all the help on my questions!

Since I already have plenty of the cheap thin Harbor Freight teflon tape I use and T-Bone says they are now calling for 4 turns and others talked about using thicker tape and tape plus another sealer, I decided to use more turns and try again before doing anything else.

When I dissassembled it I couldn't see the tape. Perhaps I didn't put as much teflon on it as I thought I had. It couldn't have gotten into the water line as I always start after the first thread. I took a wire brush and gently brushed it and did pull some off of the male plastic threads. The brass female thread had nono stuck to them. I put 6 turns on it starting 2 or so threads from the end. I snugged it down and I can't see any water drops forming. I'll check it after dinner to be sure.

Happy Thanksgiving to everyone. And thanks again for the help.

• Genova Fittings

I only used teflon on the 1/2" pipe. This is a plastic mail to brass female joint. I tried it first w/o any teflon and it sprayed water. I notice the plastic piece says not to use pipe dope or let it contact substances that contain Volatile Organic Compounds.

I'm going to try more tape tonight. Mine is pretty thin and I have plenty of it. I'm a bit cheap and that plastic contraption that adapted my 1/2" PB to 1/2" mail pipe was $5 and the Brass 1/2" pipe to 3/8 compression was $4 plus all this running to Lowes is driving me nuts. If more tape doesn't fix it I'll let it weep for a week or so and see if it stops--I've seen them stop before but don't know why. If that don't work I'll go back to lowes and try to decide whether to get a new plastic or brass or both pieces.

I read that too about not using any type of sealer on plastic fittings. I never could do that and always used a soft sealant instead of teflon tape.

If this is a barbed fitting, try using a brass barbed fitting. If you must use the plastic, then Leak Loc is a excellant product. Obtain at any refrigeration supply house as it's made for sealing high pressure fittings. Johnstone Supply, WW Grainger, or stop by a refer repairman and see if you can't buy a used tube/jar of Leak Loc.

T_Bone

I just read the new code on this, 4 turns minimum of teflon, used to be 3. The top tail end of the tape should be in the direction that the fitting screws on. This makes the tape get tighter as the theads compress and tighten.

Leave one open thread on the end of the pipe before starting to wrap the tape. Using this method stops all tape from getting inside the pipe.

If you installed the tape in the correct direction with the joint being tight and have a leak, thow away the fitting and/or the pipe nipple as it will never seal 100%. It will always weep. Sometimes the threads don't get cut correct with the machines.

Here about 20yrs ago when Mexico pipe & pipe fittings were just becoming the norm, we had alot of thread leak failures. A large plumbing contractor took them too court and won replacement costs (labor & materials), then the threads started getting better.

T_Bone

is the compressin fitting seeping or the 1/2 pipe fitting?

The 1/2 pipe is leaking.

You might be rolling it on the wrong direction, which will cause it to try and turn off the thread when tightening it. If you hold the pipe in your left hand, start the tape with the edge facing to the right, wrap three times, keeping tension on the tape. Pull tight to break it. The tape edge will be facing to the left, and will be pulled onto the thread with the rotation of the parts as they mate.