My toilet tank is held in place by two screws, which have rusted so much that the shape in their head is almost completely disappeared. On the opposite side, they are held in place by two wingnuts made from plastic. I tried to losen one of them with pliers, but that only ended up in one wing breaking off.

Main question is: what is the best way to get it off, given the wingnuts?

I'm aware of this other question, and this is the answer I like most, which suggest using a mechnaic's nut cracker, but I have a few follow-up questions to that:

  • Is there a way to remove the bolts without cutting/drilling/breaking them? (Not that I need them, I'm just afraid of damaging the tank or the bowl in the process.) E.g., I read somewhere else that WD-40 might be enough, but did anyone actually try this with success? Also, where would I put it: between the wingnuts and the toilet bowl? Or below the head of the bolt? (It would be quite difficult to get into both places...) Or maybe with some rust-solvent?

  • Can the wingnuts also be broken by the mechanic's nut cracker? (Obviously, plastic would be easier to break than metal, but the shape might not make it easy to access.)

  • Also, as far as I see, this is a tool mostly for car shops (as the name suggests), so I guess a plumber would use some other tool. Which one would it be?

The two rusty bolts inside the tank:

enter image description here

A wingnut:

enter image description here

EDIT: Proper name for wingnuts.

UPDATE: Thanks everyone for the input. Yesterday I was able to remove one wingnut by gripping it really hard with pliers adjustable sized wrench. However, the screw itself is stuck, together with one gasket on the top, and one on the bottom.

The other one moved too a few turns, but it came to the point that now it is rotating together with the screw (and I could not find a way to stop the screw, because the head is so rusted).

  • Heat, Heat, Heat... Using penetrating oil could take hours and come with multiple failed attempts, cutting, grinding, breaking the bolt or nut completely obliterates the reuse of the item and risks damaging the toilet, when removing a corroded nut or bolt, always use heat, whether that heat be a torch with kapton tape to protect the toilet from heat or one of these amazon.com/Removal-Induction-Heating-Flameless-Corrosive/dp/… It saves you a world of headaches
    – hello moto
    Jun 9, 2020 at 18:43
  • @hellomoto : yeah, I read about the possibility of heating too, but I'm a bit concerned: won't the heat damage the tanks as well (after all it is made of porcelain...). Even if I manage to touch only the bolt with the tip of the tool, won't the heated up bolt transfer the heat to the tank?
    – Attilio
    Jun 9, 2020 at 18:47
  • Also that tool is quite expensive (for $350 I could buy a new tank...) Do you think a soldering iron would work too?
    – Attilio
    Jun 9, 2020 at 18:55

5 Answers 5


When I had the same problem, I took a 4 1/2 inch angle grinder to the bolt heads. Just be careful and try not to touch the grinder to the porcelain. Also dont grind so long that you heat up the bolts to much and be careful not to melt any plastic bits in the toilet with the grinder spray. When you are done grinding, make sure you clean out all the slag and dirt that you generate. If you only grind inside the tank, you dont have to worry if you slip a little, any marks you make will be hidden when you close the tank lid!

  • Not a bad idea at all. If you have a small enough angle grinder and you're really careful to not gouge the porcelain.
    – FreeMan
    Jun 9, 2020 at 12:47

It's called a wingnut. I see the rust on the bolt heads in the tank. Are they also rusted under the wingnuts? Those wingnuts should be replaceable at your local home center. Have you checked? If so, try some WD40 or other penetrating oil under the wingnut and let it sit for a few minutes and then try turning them with large pliers or vise grips putting equal pressure on both wings. If they break off just replace them.
The bolts and gaskets under them should also be available for purchase.

  • Thanks (I'll edit the question to say wingnut.) For the records: I don't care at all about the bolts and wingnuts, (I just don't want to damage the bowl of the tank accidentally, that's why I'd prefer not to start breaking them). And yes, the bolts are rusty all the way down, and the wingnuts won't move even a bit.
    – Attilio
    Jun 7, 2020 at 21:39
  • Once the wingnuts are off you should be able to replace the bolts. If you can't unscrew them you can probably break them off.
    – HoneyDo
    Jun 8, 2020 at 1:58
  • Clarification on my comment above. If you can't unscrew the wingnuts you might be able to break them off, freeing up the bolt.
    – HoneyDo
    Jun 9, 2020 at 14:21
  • 1
    When you replace the bolts, you may want to opt for all plastic, which won't corrode. You may need to tighten the wingnuts twice, to allow for several days worth of creep between tightenings. Jun 9, 2020 at 17:23

The plastic nuts put you in a better position than you might otherwise be, I think.

While a nut cracker would be difficult to apply to a wingnut, much less under a toilet tank, a pair of locking pliers or similar "high force" tool should be able to break (crush) the plastic nut so you can get the rusted bolts out.

Example, not endorsement:

enter image description here


Based on the updated info about the screws and bolts being tightly rusted together, I'd suggest 2 things:

  1. A heavy dose of a rust remover
    • I've had good success with PB Blaster™ in the past, but any similar product should work.
    • Give it a good several hours (or even over night) to soak in and do its job.
    • Put a disposable bowl under each nut to catch drips - you don't want it ruining the flooring.
    • See if you can loosen it by grasping the screw head with one pair of locking pliers and the nut with another pair.
  2. If that doesn't loosen things up, I'd suggest the use of a hacksaw on the nut under the bottom of the tank/bowl.
    • Cut as close to the top of the nut as you possibly can. You should be able to get most, if not all, of the nut cut off the bolt. If you can't get it all cut off, once you're down to a thin layer of nut remaining, you should be able to break the rest of the rusty bits off.
    • A hand-tool is less likely to cause damage to the porcelain coating because you're moving much slower than a power tool would and you'll notice very quickly if you are starting to cause damage. You'll have the opportunity to stop and adjust at the lightest of scratches whereas a power tool will do notable damage before you have a chance to react.
  3. Instead of sawing, use the nut cracker from the question linked in the OP.
    • If there is still concern about breaking the bowl/tank, hack sawing through part of the bolt (option 2) will leave much less material to be broken by the nut cracker, making its job easier.
  • Thanks for the tips. A couple of questions: 1. if the rust remover is capable of damaging the floor, won't it damage the tank too? (e.g. by making the hole a little bit larger, and hence causing a leak?) 2. if I cut off the sticking part, won't the bit which is stuck together with the above and lower gasket still be so strong, that I can't separate the tank (without breaking it)? (I'm afraid that I would even be worse off, because I don't have the lower bit to grip.)
    – Attilio
    Jun 9, 2020 at 18:12
  • 1
    @Attilio 1) I don't know what your floor is made of - mine is carpeted, so I'd definitely want to protect it. If yours is tile, it won't damage it, but it could soak into incompletely sealed (or older) grout. It never hurts to catch drips so you don't have to clean up. 2) it depends on how close to the top of the nut you can get in your cut. If you're within a mm or two, you'll probably be able to break the rusty bits off the remains of the bolts & you're good. Otherwise, see the just added 3rd point.
    – FreeMan
    Jun 9, 2020 at 18:20

Thanks for all the suggestions.

It turned out that under the wingnuts there were also hex-nuts holding the bolts in place. I added some WD40 on the top of the bolts, and after one day, the right bolt came off quite easily (with a wrench and a screw driver).

          _____           <--- bolt head
      <===========>       <--- hard plastic gasket
      -------------       <--- rubber gasket
        ========          <--- hole in the tank
       <=========>        <--- hard plastic gasket
          ===             <--- hexnut (stuck)
         <--->            <--- wingnut (stuck)

However, the left bolt was stuck and corroded together with the hex-nut (even the wingnut got stuck) and even the slot on the top of the bolt was almost totally eroded (so I could not use a screw driver, I was trying to hold it with pliers). So in the end I cut the top solid plastic gasket with a knife and pulled off the rubber gasket below it. My original plan was to have a better grip on the head, with the pliers in this way, but suddenly the bolt just fell through the hole (which was much bigger than its head).

TL;DR: I cut off the top plastic gasket and removed the rubber gasket on top, and at that point the bolt was free.

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