Moen 3931 spout
$35.67 at Amazon
Check it on AmazonPrice as of Oct 25, 2026, 5:40 AM EDT
See fit and limitsHow to fix a shower diverter
Find which of the three diverter types you have, then the fix and the part, from the makers’ instructions.
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Quick answer
If the knob is on the tub spout, replace the spout, or rebuild a Moen 3800 spout with its gate kit. If the diverter is a middle handle between hot and cold, replace that diverter stem.
For a slip-fit spout: Moen 3931$35.67 at AmazonPrice as of Oct 25, 2026, 5:40 AM EDT
Check it on AmazonThe part for each kind of diverter
Each fixes a different diverter, so they aren’t scored against each other. All four were new and in stock on Amazon on Oct 23, 2026.
Delta RP17453 spout
$27.25 at Amazon
Check it on AmazonPrice as of Oct 25, 2026, 5:40 AM EDT
See fit and limits
Moen 101237 gate kit
$13.99 at Amazon
Check it on AmazonPrice as of Oct 25, 2026, 5:40 AM EDT
See fit and limits
Danco 9K-2D stem
$24.31 at Amazon
Check it on AmazonPrice as of Oct 25, 2026, 5:40 AM EDT
See fit and limitsProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
Which diverter do you have?
Two questions: how many handles are on the wall, and whether the tub spout has a set screw underneath. Feel for a small cutout on the bottom of the spout, near the wall.
| What you see | Diverter type | Fix | Part |
|---|---|---|---|
| Knob on the spout, set screw underneath | Slip-fit spout diverter | Replace or rebuild the spout | Moen 3931, or Moen 101237 for a 3800 spout |
| Knob on the spout, no set screw | Threaded (IPS) spout diverter | Replace the spout | Delta RP17453 |
| Three handles, middle one switches | Three-valve diverter stem | Replace the stem and seat | Danco 9K-2D for American Standard |
| Separate diverter handle on a single-handle trim | Diverter valve in the wall | Match the maker’s part | By brand and model |
The set screw check comes straight from Moen’s INS708 sheet: a slip-fit spout has a set screw in the cutout under the spout, and an IPS (threaded) spout doesn’t. Getting this right first saves a second trip to the store, because the two kinds aren’t interchangeable on the same pipe.
Symptoms of a failing diverter
Danco’s tub spout repair guide lists these warning signs and says they usually come from worn washers, damaged seals, mineral buildup or aging parts. Where to look first is my call.
| Warning sign (Danco) | Likely cause (my call) | Where to look (my call) |
|---|---|---|
| Water keeps running from the tub spout during showers | Worn washer or seal | Tub spout diverter |
| Low water pressure from the shower head | Diverter not sealing, so water escapes at the spout | Spout, or middle stem on a 3-handle valve |
| Hard to switch between tub and shower | Mineral buildup or aging parts | Spout knob, or the diverter handle |
| Leaks around the tub spout or wall | Damaged seals | Spout connection, or the stem behind the trim |
| Worn or stuck diverter knob | Worn parts or mineral buildup | Tub spout diverter |
If diversion works and the shower is still weak, check the head before blaming the valve. Our high-pressure shower head guide covers that side.
Fix 1: replace a slip-fit diverter spout
Steps from Moen’s MT531C and INS708 sheets, with Danco’s water-off step first.
- 1Turn off the water
Danco’s guide says to turn off the water supply before you take the spout off.
- 2Remove the old spout
Loosen the set screw in the cutout with a 5/32 in. hex key, then twist and pull the spout off.
- 3Check the copper stub
It must stick out 1-1/2 to 3 in. from the finished wall, with no deep scratches, dents, kinks or bends.
- 4Clean the cut end
No burrs inside or out, and the edge not rolled inward by a dull tubing cutter.
- 5Fit the new spout
Press and twist it on upside down, and tighten the clamp screw until it just starts to bind.
- 6Turn it upright and finish
Rotate it against the wall and finish tightening by hand; Moen says don’t overtighten.
Moen says its slip-fit spouts are designed for 1/2 in. copper water tube, and the O-ring inside seals on the copper, which is why the stub has to be smooth and round. A stub shorter than 1-1/2 in. or longer than 3 in. is outside Moen’s range, so measure before you buy. A clean cut matters here, and our pipe cutter guide covers the tools.
Fix 2: replace a threaded (IPS) diverter spout
No set screw means the spout screws onto a threaded nipple. Moen’s sheet says to remove it with a strap wrench.
- 1Turn off the water
Danco’s guide says to turn off the water supply first.
- 2Unscrew the old spout
Turn the whole spout counterclockwise (Danco), with a strap wrench so the finish isn’t marked (Moen).
- 3Measure the nipple
Delta says its RP17453 threads onto a 1/2 in. IPS nipple that sticks out 5/8 to 1-5/8 in. from the finished wall.
- 4Seal and thread on
My call: replace a corroded nipple, wrap the threads with thread seal tape in the direction they tighten, and snug the spout until it points down.
Delta’s RP17453 covers both connections: it threads onto 1/2 in. IPS or sweats onto 1/2 in. copper water tube. Delta’s answers on its product page say it sweats onto smooth copper that extends 2 to 4 in. from the finished wall, and that its adapter needs at least 1-1/2 in. of copper, preferably 1-3/4 in..
The Amazon listing says 1/4 to 1 in. instead; go by Delta’s figures and measure before you buy. Our slip-on vs threaded tub spout guide covers more brands.
Fix 3: rebuild a Moen 3800 spout with the gate kit
If you have a Moen 3800 series spout, Moen sells the gate and cup seal that wear out, so the spout doesn’t have to be replaced.
- 1Take the spout off
Slip fit or IPS, as above.
- 2Release the old gate
Spread the two plastic tabs locked onto the lift rod with a small screwdriver, and pull up on the lift rod.
- 3Fit the new cup seal
Place the rubber cup washer into the new gate, with its flat side facing out.
- 4Install the gate
Slide the gate and seal into the spout with the lift rod in place, and snap the tabs together.
- 5Reinstall the spout
Put the spout back on the pipe and test the diverter.
Those steps are Moen’s, from its INS708 sheet for the 101237 gate assembly. It’s the fix to try first when the spout itself is in good shape and you like the finish, since the rest of the spout isn’t a wear part.
Fix 4: replace a three-handle diverter stem
On a three-handle valve the middle handle is the diverter. It’s a stem with a washer and seat, like the hot and cold stems beside it.
- 1Shut off the water
Danco says to shut off the water to the tub and shower first, which in many homes means the main valve. Open the tub spout to drain the line.
- 2Remove the middle handle and trim
Pull the handle screw, the handle and the sleeve or escutcheon.
- 3Unscrew the stem
Danco says to loosen and remove it with a wrench or valve removal tool; inspect the washer, seals and O-rings, and look for debris in the valve.
- 4Match the part
Take the old stem along, or use Danco’s StemFinder by length and broach.
- 5Install stem and seat
Danco’s 9K-2D includes a new seat; replace the seat when you replace the stem.
Danco lists its 9K-2D (Danco ID length 9, broach K) for American Standard Colony C105 to C332-1, Heritage N1010 to N1512 and Monogram R1010 to R1502 valves, in brass, and says it complies with the Reduction of Lead in Drinking Water Act. My call: a deep tub-and-shower socket set makes this job easier; our shower valve socket set guide covers which sizes fit.
Measure these before you buy a part
Each part fits one kind of connection. These are the numbers the makers fit by.
| Measure | How | Why it matters |
|---|---|---|
| Connection type | Set screw under the spout = slip fit; none = threaded (Moen INS708) | Slip-fit and IPS spouts aren’t interchangeable |
| Copper stub length | Finished wall to the end of the copper | Moen slip fit: 1-1/2 to 3 in.; Delta sweat: 2 to 4 in.; Delta IPS nipple: 5/8 to 1-5/8 in. |
| Pipe size | 1/2 in. copper or 1/2 in. IPS nipple | Both spouts here fit 1/2 in. only |
| Valve brand and model | Name on the trim, or the old stem in hand | Three-handle stems fit by maker and series |
| Stem length and broach | Danco’s StemFinder, or the stem itself | The 9K-2D is length 9, broach K |
My call: take a photo of the old spout from below before you remove it, and bring the old stem to the store if you’re replacing one. It saves a second trip to the store.
Tools for each fix
| Fix | Tools | Supplies |
|---|---|---|
| Slip-fit spout | 5/32 in. hex key (Moen) | Fine emery cloth if the copper needs cleaning |
| Threaded spout | Strap wrench (Moen) | Thread seal tape |
| Moen gate rebuild | Small screwdriver to spread the tabs (Moen) | Moen 101237 gate and cup seal |
| Three-handle stem | Wrench or valve removal tool (Danco), screwdriver | New stem and seat; handle screw if worn |
| Any copper stub trim | Tubing cutter with a sharp wheel, deburring tool | Moen: no burrs, no rolled edge |
A dull cutter wheel is what rolls the copper edge inward, which Moen’s MT531C sheet warns against for its slip-fit spouts. Our emery cloth guide covers cleaning the stub before the new spout goes on.
Parts, fit and limits
What each part fits, from the maker’s own page or sheet.
| Part | Key specs | Fixes | Pick it if | Skip it if |
|---|---|---|---|---|
| Moen 3931 spout | 1/2 in. slip fit on copper, 1-1/2 to 3 in. stub, ASME A112.18.1/CSA B125.1, lifetime limited warranty (Moen) | Spout diverter | Your spout has a set screw and the stub is in range | Your spout threads on (no set screw) |
| Delta RP17453 spout | Pull-down diverter; threads onto a 1/2 in. IPS nipple 5/8 to 1-5/8 in. out, or sweats onto copper 2 to 4 in. out (Delta) | Spout diverter | You have a threaded nipple, or copper you can solder to | You want a no-solder slip fit on copper; that’s the Moen |
| Moen 101237 gate kit | Gate and rubber cup seal for Moen 3800 series spouts (Moen) | Spout diverter | You have a Moen 3800 spout in good shape | Your spout isn’t a Moen 3800 |
| Danco 9K-2D stem | Brass, length 9, broach K, seat included; fits American Standard Colony, Heritage, Monogram (Danco) | Middle stem | You have one of those American Standard three-handle valves | Your valve is another brand; match the old stem |
Two listing notes. Moen’s spec sheet gives the 3931 as 5-3/16 in. long, while Moen’s product page and the Amazon title say 5.5 in.. Delta’s page gives the RP17453 a 5-1/4 in. total length, while its Amazon listing says 6 in.. Neither difference changes the fit, which depends on the connection, but don’t expect a perfect match to an old spout’s length.
When to do it yourself and when to call a plumber
DIY
Any tub spout swap, and the Moen 3800 gate rebuild.
DIY with a socket set
A three-handle diverter stem when you can shut off the water.
Call a plumber
A copper stub too short, too long or damaged: the fix is inside the wall.
Plumber job
A corroded valve body or a stem that won’t come out.
My call: the spout jobs are the easiest plumbing repairs in a bathroom, and a homeowner can do them in a lunch break. Once the fix means cutting into tile to lengthen copper or free a seized stem, it’s worth a plumber’s visit. Our DIY vs plumber guide has the general rules, and how to replace a shower cartridge covers single-handle valves.
Questions people ask
Why does water still come out of the tub spout when the shower is on?
The diverter isn’t sealing. On a spout diverter the gate or seal inside the spout is worn; on a three-handle valve it’s the middle stem’s washer or seat.
How do I know if my tub spout is slip-fit or threaded?
Look under the spout near the wall. Moen says a slip-fit spout has a set screw in a cutout there; a threaded (IPS) spout has none.
Can I fix a tub spout diverter without replacing the spout?
On a Moen 3800 series spout, yes: Moen’s 101237 gate and cup seal rebuild it. Most other spouts are replaced whole.
What size hex key removes a tub spout set screw?
Moen’s sheets call for a 5/32 in. hex wrench on its slip-fit spouts.
How far should copper stick out for a slip-fit spout?
Moen gives 1-1/2 in. minimum and 3 in. maximum from the finished wall for its slip-fit spouts.
Where is the diverter on a three-handle shower?
It’s the middle handle. It turns a stem, like the hot and cold handles, that sends water to the spout or the shower head.
Do I need to turn off the water to replace a tub spout?
Yes. Danco’s repair guide says to turn off the water supply before removing the spout, and to shut it off before a three-handle diverter stem too.
Will any tub spout fit my shower?
No. Match the connection (slip fit or IPS) and the stub length; Delta’s RP17453 threads onto an IPS nipple 5/8 to 1-5/8 in. out or sweats onto copper 2 to 4 in. out, per Delta.
How we checked these fixes
Why trust me
I’m Isaac Daniels, a licensed journeyman plumber in Georgia (license #JP507711). I’ve used every part on this page. The steps come from Moen’s INS708 and MT531C sheets, Moen’s 3929/3931 spec sheet, Delta’s RP17453 page and answers, Danco’s 9K-2D page and Danco’s tub spout repair guide; my own advice is marked “my call.”
How I pick
- Each part fixes a different diverter, so they’re a kit, not scored against each other.
- Fit facts come from the maker; where a listing disagrees, the page says so.
- Genuine maker parts only, new and in stock on Amazon on Oct 23, 2026.
- No plumbing services are offered here.
Sources
- Moen, INS708 tub spout gate assembly instructions; MT531C slip-fit spout installation; 3929/3931 diverter tub spout specification (rev. 11/16); 3931 and 101237 product pages (moen.com).
- Delta Faucet, RP17453 tub spout pull-down diverter product page, including Delta’s answers on fit (2017, 2024) (deltafaucet.com).
- Danco, 9K-2D diverter stem for American Standard tub/shower faucets, model 15822B; “How to Repair a Tub Spout” (Dec 15, 2021) (danco.com).
- Product listing details (Amazon Creators API, Oct 23, 2026).
- Google results for “how to fix a shower diverter”, seen Oct 23, 2026. Search volumes from Semrush, Oct 23, 2026.