I'm working to remove the fill valve from my (quite old) Kohler toilet. Drained the tank, unhooked the water supply, now trying to remove the locknut. Trouble is (and forgive me, I'm not sure if this is common) the locknut is plastic and two pieces that seem to lock together. So when I attempted to unscrew it, the lower half of the locknut came off (as it kind of unhinged from the top part), but the upper half of the plastic locknut which is up against the porcelain just won't budge. What's the trick to getting that last piece off? I've tried using a wrench but I'm afraid of damaging the plastic or the porcelain. Thanks!

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  • 1
    @isherwood is right. That second piece is a cheap torque wrench allowing you to tighten it just so much before it slips but won't slip when loosening it. You have to hole it in place.
    – JACK
    Sep 9 '20 at 21:53
  • The nut must be pushed up to stay engaged while torque may be pushing it away due the nylon rounded edge. If you want to avoid damage to plastic replicate the nut hole and 4 slots in a harder material such as a piece of hardwood or flat metal with a hole and 4 filed slots on a length, long enough to become a better tool to engage with a snug fit and sharp edge against the rounded slot in the nylon. Sep 9 '20 at 22:31
  • @TonyStewartSunnyskyguyEE75, answers go down there
    – isherwood
    Sep 10 '20 at 12:51
  • To make it an answer, I’d need to know if the part must replaced or preserved and if he has the material to make a better tool or can as much upward force as rotational force. Sep 10 '20 at 12:56

If the plastic part you are removing is headed to the scrap/trash/recycle it might be ripe for "crush it with locking pliers" as a brute force removal technique that should still be low-stress for the porcelain.

At some intermediate level, grab it with locking pliers to unscrew since it does not have much for a wrench to grab might apply, but it might just break anyway.

If you are trying to preserve it, but remove it, good luck.

  • Correct. They are designed as one-time use devices, in removing them, you destroy them. So get the Channel Locks on it and remove it, you can't save it. The new valve will come with a new nut anyway.
    – JRaef
    Sep 10 '20 at 0:20
  • ViseGrips are my preferred weapon in this fight - proof that I'm not a real plumber, but they are great for crushing things ;-)
    – Ecnerwal
    Sep 10 '20 at 0:24

That piece is essentially a slotted socket wrench. It's probably intended to break away under severe tightening force rather than crack the porcelain or damage the valve parts.

Put the piece back on and use a hex wrench on the assembly. You'll have to hold it there while you turn it, just as you would the hex wrench.

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