How to Fix Leaky Toilet Tank Bolts? [10 Minute Fix]

Leaky toilet tank bolts are not a serious toilet problem. It’s an indication that the tank bolts or rubber washers are somehow damaged and you need to just replace the old ones with a fresh new set.

Are you using the American Standard, Kohler, or any other two-piece toilet brand? Here are the likely reasons why the toilet tank bolts would leak.

fix leaky toilet tank bolts

Reasons Behind Leaky American Standard Toilet Tank Bolts

Though there are universal toilet tank bolts, American Standard and Kohler toilet brands have their tank bolt kits.

To understand the issue properly, you’ll need to understand how the toilet tanks are installed using bolts.

Most American Standard toilet models use two tank bolts that attach the toilet tank to the toilet bowl.

The bolts pass through openings around the flush valve at the bottom of the tank. They extend into the matching holes on the toilet bowl to hold the tank firmly in place.

Unlike the Kohler models that use a rubber washer, American Standard toilet models use a rubber compression cone seal.

The kits are arranged in such a way that the bolt head sinks inside the rubber compression cone seal inside the toilet tank. The rubber compression cone seal creates a perfect seal against leaks.

A flat metal washer and hex nut come immediately under the tank to hold the bolt in place. A rubber washer, flat metal washer, and hex nut (or locknut) come after the toilet bowl in that order.

american style toilet bolts diagram

The main reason behind leaky American Standard toilet tank bolts is a damaged compression cone seal. The compression cone seal goes inside the hole to prevent water from leaking from the tank. Being rubber, the cone seal may wear out with time, causing water to leak through the bolt.

Sometimes the reason behind the leak can be loose bolts and nuts. The bolts and nuts must be tightened on the washers to prevent leaks. If the bolts and nuts are loose, there would be a weak seal and water will leak out.

The bolts, nuts, and metal washers may also corrode and rust over time and eventually leak.

Once you notice water dripping on the nuts or bolt ends, the tank bolts need replacement.

Sometimes, what you’ll notice is just wet brown rust around the nuts under the toilet bowl.

Why Kohler Toilet Leaking from Tank Bolts?

Most Kohler toilet models come with three tank bolts that differ in size and design from American Standard toilet tank bolts.

Kohler toilet tank bolts are thicker and use a flat rubber washer instead of a compression cone seal. The bolt head rests tightly on the rubber washer.

Nevertheless, the Kohler Toilet kits are arranged the same way as the American Standard toilet kits.

The main reason why Kohler Toilet leaks from the tank bolts is misalignment due to poor installation of the tank bolts.

kohler toilet bolts diagram

Poor alignment of the kits will create a gap that may lead to leaky toilet tank bolts. Most people don’t put the first nut carefully under the toilet tank and this usually leads to misaligned bolts.

Another reason is tight or loosened bolts. It’s normal to think that loose bolts will leak water. However, it’s surprising to know that over-tightened bolts will also leak water.

The rubber washers create a seal that prevents leakages but over-tightening can damage the rubber washer, leading to leaky bolts.

Damaged washers are another reason for leaky tank bolts. As seen in the diagrams above, the washers (rubber and metal) provide a watertight seal between the toilet tank and bowl.

Once the washers are damaged, the seal is gone and the bolts will leak water.

How to Fix Leaky Toilet Tank Bolts?

Irrespective of the toilet tank model you have, the best fix for leaky toilet tank bolts is bolt replacement.

Replacing leaky toilet tank bolts with new ones is a simple task that you can handle by yourself. However, you will need the following tools to carry out the task effectively:

  • Towels or cloths
  • Hacksaw blade (optional)
  • An adjustable wrench
  • A flathead screwdriver
  • Sponge
  • Toilet tank kit

If your toilet bolts are seriously leaking and you can’t lay your hands on the tools above or you don’t have the time yet, you can apply a temporary fix. The temporary fix will work in the meantime to stop the leakages.

Temporary Fix

Using a good sealant on the tank bolt provides a temporary fix for leaky toilet tank bolts.

  1. Shut off the water supply to the tank.
  2. Flush your toilet and drain the tank.
  3. Remove the tank lid and keep it safe.
  4. Remove excess water from the tank with a sponge.
  5. Leave the tank for some time to allow it to dry. The sealant won’t work on a wet surface.
  6. Once dried, clean around the bolt heads in the tank
  7. Apply the sealant over each bolt head. Apply a large quantity that covers the entire bolt head and adjacent areas all at once.
  8. Allow enough time for the sealant to fully cure.
  9. Close the tank and open the water supply.

This should stop the leakages temporarily. Note that it will eventually fail and the permanent fix is to replace the toilet tank kits.

Permanent Fixes

Fixing Loosened and Misaligned Toilet Tank Bolts

Fixing misaligned or loosened toilet tank bolts is very simple.

  1. Shut off the water supply and flush your toilet.
  2. Remove the tank lid and take out excess water with a sponge.
  3. With a flathead screwdriver, confirm that the bolts are loosened.
  4. Use a wrench to remove the nuts under the toilet bowl.
  5. Hold the nuts in-between the tank and bowl (if any) with a wrench and tighten the bolts with a screwdriver. Tighten the bolts and nuts to achieve a snug-fitting but don’t over-tighten to prevent cracking the porcelain.
  6. Carefully adjust the toilet tank in place on the toilet bowl so that the bolts are centered in the opening.
  7. Tighten the nuts under the toilet bowl starting with your hand before using a wrench. Don’t over-tighten.
  8. Open the water supply and fill up the tank
  9. Check for any leaks on the toilet bolts.

Replacing the Toilet Tank Kits

The best solution to damaged compression cone seal, damaged rubber washers, and/or corroded bolts/nuts/metal washers is getting a replacement kit.

Make sure that the replacement kit is suitable for your toilet’s model. Get brass bolts and nuts, they last longer than stainless-steel bolts and nuts.

These steps will guide you in installing the new toilet tank kits-

Turn off the Water Supply & Dry Up the Tank

Shut the water supply and hold down the flush lever to drain the tank.

Disconnect the rubber hose from the fill valve by turning the locknut anticlockwise

Remove the lid and use a sponge to completely remove any excess water in the bottom of the tank.

Remove Bolts

Use a flathead screwdriver to loosen the toilet bolts. You may also use a wrench to loosen the nuts under the bowl.

Corroded bolts and nuts may spin together and not come loose. Cut them off with a hacksaw blade.

Watch this video on how to remove corroded bolts between the toilet tank and bowl

Remove the Tank

Lift off the tank gently and lay it on its side.

If there are nuts directly under the tank, loosen or cut them out as the case may be.

Clean around the holes so that the new nuts and bolts can fit in place properly.

Install New Bolts

Put the new bolts through the tank. Don’t forget to arrange the new toilet tank kits as seen in the diagram above. For easy removal next time, wind some Teflon tape around the threads of the bolts.

Place the first set of metal washers and nuts under the tank and tighten the nuts with your hand.

Make sure that the bolts are centered in the hole. Use the screwdriver or wrench to tighten the bolts and nuts further. Don’t over tighten, else you may crack the tank.

New toilet tank kits always come with a tank-to-bowl gasket. If you wish to replace the old tank-to-bowl gasket, slip it out and insert the new one over the locknut.

Place the tank gently on the bowl. Make sure it aligns well.

Place the last set of metal washers and nuts under the bowl and tighten the nuts with your fingers.

Tighten them alternatively to ensure that they are balanced. Further, tighten the nuts with a wrench until the tank is stable and no longer wobbles. Don’t over tighten, else you can break the porcelain tank or bowl as I said repeatedly.

Reconnect Water Supply & Check

Reconnect the water supply hose to the fill valve and open the water supply.

Fill the tank with water and flush your toilet several times.

Check around the base of the tank to ensure that there is no leak from the bolts or around the gasket.

Watch this video on how to replace the toilet tank kits if you are still confused-

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