Compression Stop-Valve Problem

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Kiko, Nov 2, 2009.

  1. Kiko

    Kiko New Member

    Messages:
    175
    Location:
    Royal Oak, Michigan
    I have a leaky 1/4 turn angle compression stop valve under the lavatory sink. When I tried to tighten it up (using two crescent wrenches) the leak got bigger. I shut off the main and removed the screw-out part of the valve to find that the male threads had split. I installed a new valve, using the old nut and ferrule, but the same thing happened again. I tried NOT to overtighten it, but it leaked a bit, so I tightened it some more, and it leaked even worse. I assume the valve threads are split again, but I swear I did not "gorilla" tighten this valve.

    In order to try to remove the old nut and ferrule, I have to cut open the back of the vanity to get to them. Could using teflon tape on the male threads of the valve prevent it from leaking if the ferrule has become deformed a bit?

    Can someone explain what else might be going on here?
  2. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    The old ferrul may be the problem...you may be able to pull it off and install a new one but if the pipe is distorted then you will have to cut the pipe, and install a new valve or if it would be to short solder on a short peice of pipe and then install the new valve...
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,815
    Location:
    Cave Creek, Arizona
    valve

    YOu could have a mismatch on the threads of the nut and valve. There are some older valves which have a coarse thread and cannot be used with the new valve. You DO NOT have to open the back of the cabinet to remove the nut and ferrule. You DO have to use a ferrule puller to do it, however.

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    Last edited by a moderator: Jan 12, 2010
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Teflon tape on a compression fitting almost always makes it leak. Some lube, like a few drops of oil or plumbers grease, is good.
  5. Kiko

    Kiko New Member

    Messages:
    175
    Location:
    Royal Oak, Michigan
    Ferrule Puller

    They sell a combination handle/ferrule puller for about $10, and a dedicated ferrule puller for $35. Do they work equally as well or should I shell out the dough for the expensive one? In order to cut the pipe, I definitely would have to carve out the back of the vanity, which will be tricky, since the space is very tiny to work in with a spiral saw.
  6. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,143
    Location:
    South*East
    You can remove the ferrule with a hack saw blade and screwdriver. Use the hacksaw blade to parshley cut through the ferrule with out cutting the copper, then twist the blade of the screwdriver in the slot. That should split the ferrule.

    John
  7. Kiko

    Kiko New Member

    Messages:
    175
    Location:
    Royal Oak, Michigan
    Thanks to Terry for the pic. I guess that must be the more expensive model.

    As far as the hacksaw is concerned, I doubt there is room to use even a small one. If I was going to go that route, I might use a dremel to cut off the ferrule.

    Once the ferrule is removed, there will only be 1/2" of pipe to work with. I heard about sharkbite stop-valves. Can someone give me instructions on how to install one of those. That might be easier than trying to put on another compression valve.
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,815
    Location:
    Cave Creek, Arizona
    pipe

    There will be just as much pipe to work with as the existing valve had. DO NOT cut any pipe. Do not use a Dremel tool unless you have a very steady hand. If you nick, notch, or do anything else to the tubing, then you WILL have to cut it shorter.
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