Plumbing: Impossible Valve Stem

I have a soaking bathtub with a leak from Kohler washerless faucets. But, the valve stem’s hex nut pattern seems to be a non-standard size of 15/16" - smack between two stem socket wrench sizes! AND! Using your everyday socket wrench set, this is EXACTLY where the industry switches from 6-points to 12-points! (unless some larger 12-pt socket - or maybe metric socket? - can possibly mate with a 6-pt hex nut pattern? …assuming such a socket can even pass through the tight clearance to gain access to the countersunk hex nut base of the valve stem!!!)

I was told there may be a special Kohler wrench…does anyone have expereince with Kohler valve stems? My tub is 13 years old, by the way, and the faucets are “deck mounted” (as opposed to wall mounted). Also, there is no access panel by which to gain access to the hex pattern with channel locks or any other monkey wrench.

And, if I finally do pull the valve stem, will the seat fit a standard seat wrench, or did Kohler get me yet again!?

Any help or pointers would be great!

  • Jinx

I would try the hardware store. Sometimes they make special sockets that are sort of generic size with pins that fit any size nut you put it on. I played with one the other day there. Im sure they have something to do it if you look in a store like that nearby.

handy is right, especially if you go to a big hardware store that is operated by people who want to help, rather than listless zombies. I found a cheap Kohler valve stem this summer from a local plumbing store ( in the phone book under plumbing and heating)

Dunno if this helps, but I just saw a combination 29/32" and 31/32" socket for $6.95 at a big box home improvement store. If these are the standard sizes, then what’s 1/32", give or take? You should still be able to get a grip on the valve and it shouldn’t be torqued in to the point where you round off the flats.

Have an old Kohler shower, trying to remove and replace all three valve stems, started with a ‘this is a universal size’ socket sold to me at a hardware store. One end is 29/32, the other 31/32. One size to small, the other too large, so 15/16 is it, right?

Finally was able to borrow a 15/16 socket from a friend, it’s just a tad to big and doesn’t have enough grasp to avoid rounding the nut corners. So, I figure it must be metric.

15/16 = 23.81mm, so I figure a 23 mm will do it, right? Hard to find, but bought one and guess what? too small. Do they make 23.5mm sockets?

I am now convinced I need a special socket for this, any suggestions? I am trying to find one online.

Byt the way I am 4 weeks into this, visiting various hardware stores, etc.


You might try this:

It could be a 24 mm nut. My truck has a couple of plugs that are likely 24 mm, but a 15/16’’ wrench works fine. You may have to hit an autoparts store to find either. The 15/16’’ fits a little tighter than most wrenches, but works.

I recently had to replace the spout on my Moen kitchen faucet I installed in 2006. I was surprised to find it metric. I was pleased, I called Moen on Monday reported the spout cracked. I had a new free one in Thursday’s mail.

Yeah, I was just thinking an auto parts store might be a good idea.

You’re faucet gizmo is in the size range of spark plugs, and they make weird sockets to retrieve them.

Naw, the older sparkplugs were 13/16’’. The newer ones are 5/8’’, 16mm.

Is this too big around to fit where you’re working? Gator Grip. It has a bunch of pins inside the socket which all crush together when you turn it.

Not the regular sockets but the Automotive Spark Plug 6-point socket. It’s a tad loose but because it’s a 6-point socket it works. I’ve had to use it on two different 2-lever Kohler tub and shower faucet valves. Don’t use the 12-point or you’ll be crying when it slips.

As for the leaking part, take off the rubber seat that seals the valve shut and slip on a #208 O-Ring ((9/16" OD 3/32" ID). It’s tight but you can stretch it over the ceramic valve. Then replace the worn rubber seat. It makes the seat sit higher and will allow you to shut the valve and stop the leak.

I suggest this as a temporary fix until you can replace the valve. I’ve done this twice on two different valves and it’s been over a year and it’s still holding.


What size wrench fits a 14 year old zombie?


I just finished a job like this. I got a 24mm socket from the auto parts store 6 points deep socket. It cost about 8 dollars. I had to grind an area for the pipe wrench to grab cause it kept slipping.

Look for Stanley universal sockets

Here are the wrenches, look closely you’ll see they fit 6 point,12 point, 8 point, square, etc.


They’re are very handy on fasteners likely to round off. The teeth in them are pretty sharp by compare to most.

They do have socket versions, usually black but look at the pattern on the more common wrench set first so you can ID the sockets.

Awesome tool!

They’ll usually snag any sort of oddball by virtue of their geometry too.

Got to harbor freight and buy a shower socket set. About 12 bux, it will be exactly what you need.

I bought a 6 point 1/2” drive deep impact socket that had a 1/4” hole at the base. I put a 1/4x20x1/2” screw in the hole which gave my channel lock pliers something to grab. This is similar to a previous thread where the guy ground down the socket but no modification required. Worked like a charm. 30 minutes later the seats were replaced and valves reassembled.

I used a 24mm socket

I hope that it hasn’t been leaking since November 2001.