How to Remove a Stuck Plastic Lock Nut From a Toilet Tank

In every toilet tank, there are plastic lock nuts that secure various fixtures in place. They are strong enough to provide solid support to secure the fill valve and other fixtures. However, one misstep can damage the locknut, making it a nightmare to remove.

Regardless of why you need to remove the plastic lock nut from your toilet tank, we are here to help you figure it out.

How To Properly Loosen Plastic Lock Nuts

To loosen plastic lock nuts on a toilet tank, you will need a few items, including:

  • Towels
  • Regular pliers, adjustable wrench, or spud wrench

First off, you need to shut off the water supply and drain the tank unless you are ready to deal with the following mess. The water supply valve on the toilet is easy to find. Simply follow the supply hose to where it connects to the supply valve, which is located on the wall.

Once you have located the supply valve, turn the handle all the way to the right to cut off the water supply.

Next, drain the water in the toilet tank. Remove the lid of the toilet tank and carefully place it aside. To drain the tank, press down on the handle to flush the toilet. Continue doing so until the entirety of the water has drained. If there is residual water in the bottom of the tank, use a towel to soak it up.

Take another towel and lay it out on the floor underneath the tank. On the underpart of the toilet tank, there is a plastic piece that connects the water supply hose to the tank. Unscrew the plastic piece.

Once you have disconnected the water supply hose, locate the lock nut. It should be right above where the coupling was connected to the tank. It is a reasonably large plastic nut.

To remove the nut, you can use whichever tool you choose: a pair of pliers, a spud wrench (specifically designed for removing hex nuts), or an adjustable wrench. Turn the plastic nut counterclockwise to remove it.

How To Remove A Stuck Locknut

How To Remove A Stuck Locknut

Now, if you have completed the steps outlined above and the locknut refuses to budge, you have a couple of options you can try. Plastic lock nuts can be tricky to remove as they can damage easily.

Plumber’s Grease

One of the best ways to remove a difficult lock nut is by using plumber’s grease. Simply apply the plumber’s grease to lubricate the plastic nut, then let it sit for 10 to 15 minutes. Once that has sat for a while, attempt to remove it using your hands or a pair of pliers.

Try A Hot Rag

To remove the stubborn lock nut, you can try to use a hot wet rag or towel to lubricate it. For this method, you’ll need:

  • A hot damp rag or towel
  • Strap wrench, basin wrench, or pipe wrench

Hold the rag under hot water until it is saturated, then wring it out. Hold the hot wet rag or towel against the lock nut for a few minutes. This should help lubricate the lock nut enough to remove it.

Once you have heated the lock nut, use a strap wrench, basin wrench, or pipe wrench to attempt to remove it. Do so by turning counterclockwise.

Try Locking Pliers

Now, if the locknut is still firmly fixed in place, you can try to use a pair of pliers to unscrew it. For this method, you need a pair of locking pliers.

Locking Pliers

Set the pliers on the narrowest setting that will fit around the lock nut. Fit the pliers around the lock nut. Come from either the top or bottom, not the side. Using both hands, grip the pliers while rotating to spin the nut.

Angle Grinder

If all other methods fail to do the trick, you can try using an angle grinder to slice through the plastic. This method may not always do the trick because some angle grinders will not fit in the close quarters of the tank.

For this method, you’ll need:

  • Angle grinder
  • Safety goggles
  • Gloves
  • Flathead screwdriver

Wearing safety gear, use the angle grinder to cut through the plastic nut carefully. Use caution as not to go too deep or cut through anything else. Once you have cut through the nut, use the flathead screwdriver to push the two ends apart, then remove the lock nut with your hands.

How To Loosen Faucet Mounting Nuts

Removing faucet mounting nuts is somewhat similar to removing lock nuts on a toilet tank. As with any projects that involve taking apart faucets, toilets, or the like, remember to shut off the water supply to the faucet.

To loosen faucet mounting nuts, use channel-type pliers to grip the nut that holds the faucet body in place. Rotate the nut counterclockwise to remove it. There may also be a spout mounting nut. If there is, use the same techniques.

How To Get Plastic Nuts Off A Faucet

Plastic nuts on faucets can be a bit tricky, as some of them may have shapes that prevent a basic basin wrench from efficiently removing it.

However, with that said, you can try to use a basin wrench, which can be used as a tool to remove plastic faucet nuts. Position the jaws of the wrench onto the faucet nut. Face them in the proper direction, so they will allow you to turn the nut counterclockwise.

How To Get Plastic Nuts Off A Faucet

If that didn’t do the trick, you could also try to use a screwdriver and hammer. Use a flathead screwdriver positioned on the plastic nibs of the nut and a hammer. Tap the screwdriver to loosen the nut.

Another method to try is with heat or a calcium dissolver. A hairdryer can soften the nut to make it easier to remove. Calcium dissolver may also help with removal – allow it to sit for a few minutes before attempting to remove the nut.

You also can try a lubricant like WD-40 to help loosen the nut. However, if you choose to use a lubricant, don’t follow with heat, as many lubricants are flammable.

1 thought on “How to Remove a Stuck Plastic Lock Nut From a Toilet Tank”

  1. I couldn’t get the plastic locking thing off the value control unit using the ways you described. But I thought about using a rubber band around the nut for traction and it worked so fast and easy.


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