How to Remove a Rusted Nut From a Screw Under the Toilet

Written by c.l. rease
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How to Remove a Rusted Nut From a Screw Under the Toilet
Rusted fasteners are commonplace under toilets. (Jupiterimages/ Images)

Leaking water and condensation cause the connection between the water tank and the toilet base to rust. The rust causes the nuts located under the toilet to lock together, making them difficult to remove. Using the wrong removal methods can cause the porcelain water tank or the porcelain toilet to crack. When either component cracks, that component will need to be replaced. This adds additional cost to your toilet repair. Working slowly and being patient will allow you to remove the nuts from under the toilet without damaging either toilet component.

Skill level:

Things you need

  • Penetrating oil
  • Screwdriver set
  • Adjustable wrench

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  1. 1

    Turn the valve connected to the toilet water supply line clockwise to shut off the water to the toilet. Flush the toilet to drain water from the upper storage tank.

  2. 2

    Spray lubricating oil on the each screw head sitting inside the water tank. Spray penetrating oil on the rusted nuts located under the toilet tank. Allow the oil to sit on the screw heads and nuts for seven to eight hours.

  3. 3

    Select a screwdriver from a screwdriver set that matches the style and size of the screw heads located inside the water tank.

  4. 4

    Turn the rusted nuts located on the underside of the water tank counterclockwise with an adjustable wrench. Apply additional penetrating oil on the nuts and allow it to sit for six hours if the nuts do not move. Do not apply excessive pressure to the nuts or the toilet components will crack.

  5. 5

    Alternate spraying oil on the rusted parts and turning the nuts with an adjustable wrench until the nuts remove from the threads of the screws. You may need to make multiple attempts over the course of two or three days to loosen the rusted connection.

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