How to fix shower knob that wont turn

By Cecilia Harsch Updated December 10, 2018

A bathtub faucet handle and stem are designed to work together. The inside of the faucet and outside of the stem are like two cog pieces, with one cog’s teeth turning the next cog. When one cog wears out from years of use, it can no longer turn the next cog. If the bathtub faucet won't turn off, the trickle of water could increase your water bill, and when the faucet won't turn on, it can cause frustration. Before moving to replace the stem or faucet, try some minor repairs to get your faucet turning again.

1. Pry the handle cap from the center of the faucet handle with a small flat-blade screwdriver to expose the handle screw. Tighten the handle screw with a Phillips screwdriver.

2. Rotate the bathroom faucet on or off to see if tightening the screw helps resolve the issue. If the faucet still fails to turn off or on, try repairing the end of the stem.

3. Turn off the water supply valve to your bathtub faucet. If you can't access the shut-off valve to the faucet, turn off the water supply where it enters your home, or use a meter key to turn off the water supply at the water meter. Turn on a faucet inside your home to drain the water from your lines.

4. Remove the handle screw from the faucet. Pull the handle off the stem.

5. Inspect the end of the faucet stem for damage. The tip of the stem should have ridges that connect with the ridges inside the faucet handle. If these are worn or damaged, the faucet handle can’t grip the stem and turn the faucet on or off.

6. Look inside the faucet handle for damage. A cracked handle would need replacing, as it cannot grip the faucet stem. If the ridges inside the handle are worn, the handle cannot connect with the stem and control the faucet.

7. Clean the end of the stem with an old toothbrush to remove any water deposits. Wipe the stem dry with a rag.

8. Wrap one or two layers of thread-seal tape around the tip of the valve stem. Push the handle over the thread-seal tape and onto the stem.

9. Insert the handle screw through the top of the handle and into the stem. Tighten the screw and replace the handle cap.

10. Turn the water supply back onto the bathtub faucet. Attempt to turn the water off and on. The thread-seal tape should add one or two more years to the life of the stem and the handle, and allow the faucet to turn.

    Things You Will Need

    • Small flat-blade screwdriver

    • Phillips screwdriver

    • Meter key

    • Old toothbrush

    • Rag

    • Thread-seal tape

Perhaps your shower knob simply twirls when you try to turn the water on, or maybe the showerhead continually leaks, and you can’t shut it off, no matter how far you turn the handle. This might not be a big deal in homes with multiple bathrooms with showers. However, if your only shower is giving you grief, things can get dicey after just a few days without showering. 

Regardless of if you have several shower options or just one, you should probably fix the broken knob sooner rather than later. We’re here to help you get your shower back up and running, so continue reading to learn more!

Why Is My Shower Knob Spinning?

If your shower knob performs a mini-ballet dance, complete with multiple twirls every time you try to turn the water on, a few things might be happening. 

In some cases, the culprit may be a faulty handle. Many shower faucets feature plastic knobs that are susceptible to damage over time. When the handle cracks, it doesn’t provide the tension necessary to turn the water on. If this is the problem, all you’ll need to do is replace the handle. 

However, in other cases, the knob spins freely on its axis because of stripped parts. When this happens, you’ll have to replace the entire valve. Unfortunately, you can’t typically replace just the shower valve stem itself; you’ll need to buy a complete replacement of the valve. 

How To Fix A Spinning Shower Knob

Now that we’ve addressed the potential culprits of the issue, we can move on to the fixes. If the handle is faulty, the fix is pretty straightforward. On the flip side, if a stripped valve stem is the problem, the repair is a bit more involved. 

Before you call a plumber, try these fixes. 

Tighten The Set Screw

Before we go overboard working on these fixes, let’s try a quick fix first. In some cases, this might correct the problem altogether, saving you the trouble of replacing a valve stem or broken handle. Here’s what you’ll need:

• Flathead screwdriver
• Philips screwdriver or hex wrench
• Thread locking compound

Using a flathead screwdriver, gently pry off the cap that covers the set screw holding the handle in place. Generally, the cap sits at the front of the knob and displays the manufacturer’s logo or a red and blue circle (indicating hot and cold). 

If you have a lever-style shower handle, the cap is usually under the lever, which requires more searching. Once you find it, remove the cap to expose the set screw. For side mount screws, you’ll probably need a hex wrench (Allen wrench), but for top mount screws, you’ll probably need a screwdriver. 

Sometimes, the screw manages to work its way out slightly, allowing the handle to spin instead of catching as it should. If so, all you need to do is tighten the screw with your hex wrench or screwdriver. Before you tighten it, remove it entirely and apply some thread-locking compound to the threads, which will prevent this from happening again. 

Reinsert the screw, then tighten it into place. Don’t overtighten the screw, as that could strip the threads, which will bring you back to square one, but with a trickier fix. 

Try A Temporary Fix

In some scenarios, tightening the screw won’t do the trick. If this is the only shower in your home and you need it now but don’t have the time to go out and get parts, try this temporary fix. Note: This is only a temporary fix and won’t solve the problem indefinitely. 

Here’s what you’ll need:

• Plumbing tape
• Screwdriver or hex wrench

Remove the screw from the knob. Wrap about three or four turns of plumbing tape around the valve stem. The key here is to get the handle to sit tightly in place, but not too tight, or the handle won’t fit back on the stem. 

Once you apply the tape, fit the handle back onto the stem. Replace the screw, then check your work. While this won’t work as a permanent fix, it should buy you some time.

Replace The Handle

If you’re committed to fixing things the right way the first time, here’s how to fix the handle. First, make sure the handle is the problem. Remove it from the valve stem by unthreading the screw and removing it altogether. 

Next, examine the handle for cracks and splits throughout. If you find any, there’s a good chance that the handle is the root of the issue. If you don’t want to buy a replacement handle, you can try fixing the crack with two-part epoxy glue. This glue is some strong stuff, but it may or may not work, depending on where the crack is. 

If the crack is in a repairable location, use a C-clamp to squeeze the handle together after applying the glue. Allow it to dry completely, then remove the clamp and reinstall the handle. 

Alternatively, if the crack is too big to repair, replace it. Generally, it’s best to buy a matching replacement from the same brand instead of mixing and matching generic brands, but you might be able to find a generic replacement that will work. 

Once you remove the handle, take it with you to the hardware store to find a matching replacement. Or, if you want the exact replacement, order one from the manufacturer directly or through an online plumbing parts outlet. Parts usually arrive within 3-5 days, but it varies from one supplier to the next. 

Replace The Shower Valve Stem

If the stem is stripped and allows the handle to spin freely, you’ll need to replace the entire valve. Before you get started, turn off the water supply to the shower. Sometimes, you’ll find a shut-off valve controlling the shower itself, but if you can’t, turn off the water main to your house. 

Once the water is off, unthread the set screw, then remove it along with the handle. Unscrew the valve retaining nut, then remove the valve. In some cases, like with a Moen shower handle, you might need to pull out a retaining clip using pliers in order to remove the valve. 

Sometimes, mineral deposits will fix the valve in place. If that’s the case, you might have to use a valve remover to force out the valve. These corkscrew-like devices are generally available for rent from various locations. Or, you could buy one or borrow one from a neighbor. 

Once you remove the valve, take it with you to the hardware store to find a replacement. Alternatively, look for the replacement on the manufacturer’s website or an online plumbing parts supplier. Again, ordering parts usually takes 3-5 days before they arrive, but it depends on the shipping situation with that particular seller. 

Once the part arrives, install it following the manufacturer’s instructions. After installing it, check your handiwork, ensuring the handle operates normally, and there aren’t any water leaks.