Fixing stripped stem end so shower knob can grip again?

[learningdiy]

I've just successfully repaired a leaky hot water shower by replacing the washer on end of stem. I've confirmed this fixes the leak, but now unfortunately the Sayco handle is slipping and not turning the water on/off again. I tried out the handle on the other step and it grips fine, so it looks like the issue is the grooves on the end of the stem itself.

Is there any way to get some additional mileage out of the stripped end of the stem? I'm not sure if "stripped" is even the right word--the groves are still very visible, but they have are worn down a bit. I tried plumber's tape, but it wasn't enough to allow the handle to grip. Are there other plumber's tricks I could try?

Thanks in advance!

 

[Twowaxhack]

Replace the stem

 

[learningdiy]

Thanks @Twowaxhack that's my other option. I'm having a hard time finding the right stem replacement, so was hoping for a stop-gap with the current stem while I figure that out.

 

[Twowaxhack]

Sayco stems are common. They’re cheap too

 

[learningdiy]

I appreciate the confidence @Twowaxhack but I'm having trouble getting new stems to work.

• When I screw the existing one back in and turn the water back on, there is no water coming out. So the old one seals well, despite the problem with the stripped grooves.
• When I screw one of these new ones in and turn the water back on, a light stream of water comes out even when it is closed. So the handle grips well on the new one, but it doesn't seem to actually seal.

The only visible difference I see is that the new ones seem to be lacking a rubber washer toward the end (but not at the very end). Here's a photo that illustrates the missing washer. Any suggestions?

 

[Twowaxhack]

No, nothing goes there for a hot or cold stem. That groove is for an oring on a diverter stem. It’s not needed on a hot or cold stem.

Show a pic of your old stem

 

[pasadena_commut]

Does the OP have hard water? It is possible that the handle was a little loose for a long time and the grooves in the handle filled up with calcium deposits. The handle might have worked like that before it was taken off because it was in effect cemented to the stem. However, once removed the grooves will not engage adequately with the handle. If this is the case then soaking the grooved end of the stem in vinegar will remove the deposits and allow the handle to fully engage. Usually the hole in the handle will still have calcium in it too, and it should be cleaned as well.

Or the grooves might really be mangled, in which case a new stem is the solution, as suggested previously.

I suppose if one was really, really desperate, for a stem which was literally impossible to obtain, one could have a machine shop repair the grooves somehow. LIke cut off the original shaft, cut off a grooved shaft from a donor stem, and weld the donor onto the original. But if custom machine shop work is the only solution replacing the valve(s) in the wall might be a saner choice.

 

[Bird Doo Head]

Often wrapping the stem in steel wool before putting on the handle works with machinery knobs and dials. It worked for years on an old Central Brass tub faucet that I had.

Last Ditch Effort If You Can't Find A Stem:
Lubricate the stem with a very light coating of oil. Fill the handle's opening with epoxy paste. Push the handle on, screw it in to keep it straight & wait for cure. Remove handle and clean the oil off of the stem.

The new grooves in the handle epoxy will match what's left on the stem. Usually it works with machine knobs, but sometimes not. (It's last ditch because if you don't oil the stem well and the knob gets glued to the stem...)

Paul

 

[pasadena_commut]

Last ditch is right. On our tub the handles have to come off to remove the nut which holds the stems in. If the handle is cemented on it will have to be broken up or cut apart to provide clearance for that nut if the stem needs service - like a new washer on the tip to fix a drip.

 

[Bird Doo Head]

Last ditch is right. On our tub the handles have to come off to remove the nut which holds the stems in. If the handle is cemented on it will have to be broken up or cut apart to provide clearance for that nut if the stem needs service - like a new washer on the tip to fix a drip.

That's why I put oil on the stem before using the epoxy. It'll slide off after the epoxy cures.
All the epoxy does is make the worn out inside of the handle match the worn out stem so that they can grip each other.

 

[learningdiy]

Per @Twowaxhack's request, here's a picture of the new stem (left) next to the old/current stem (right). The white stuff on the bottom of the old stem is the remnants of the failed plumber's tape effort. You can see the old stem has an additional black washer about 5mm from the top end.

 

[Twowaxhack]

Yeah that oring doesn’t do anything on the hot and cold stems. It shouldn’t be there.

The washers that come on new stems are crap. It’s probably deforming the washer when you turn it off and then drips.

The replacement stem is correct.

 

[learningdiy]

Yeah that oring doesn’t do anything on the hot and cold stems. It shouldn’t be there.

The washers that come on new stems are crap. It’s probably deforming the washer when you turn it off and then drips.

The replacement stem is correct.

So do you think it's worth trying to just replace the washer on the end of the stem? Seems weird that the ones coming with the unit are low quality, but cheap to buy some fresh ones and try it if you think that might help.

 

[learningdiy]

Tried replacing the washer with a new one, and it still doesn't seal correctly. Even tried taking the washer from the old one and putting it on the new stem, but it still leaks.

I put the old stem back in, and it seals fine. Just need to figure out how to get the handle to grip again.

 

[Twowaxhack]

Tried replacing the washer with a new one, and it still doesn't seal correctly. Even tried taking the washer from the old one and putting it on the new stem, but it still leaks.

I put the old stem back in, and it seals fine. Just need to figure out how to get the handle to grip again.

You understand that makes zero sense ?

Buy another stem and try it. The answer is to replace the stem.

 

[MicEd69]

From the picture, the old stem appears to be slightly larger in diameter. And there also appears to be a slight difference in the threads at the O-ring; they appear longer on the new one.

Could those two issues keep the washer from sealing tightly against the valve seat?

 

[Twowaxhack]

There are often slight differences in remanufactured stems but they still should operate.

I would replace them stem with another one just incase. I suggested that.

This is a very common faucet. I’ve worked on them for 30 yrs with high success rate.

 

[pasadena_commut]

Is there a seat on this valve? It may be nicked or damaged in some other way. If that is the case it will leak (out of the faucet, I guess that is a drip, not a leak) with a perfectly good stem. With the stem out look into the hole with a flashlight for a hexagonal hole the size of a large Allen key. Usually the seats just screw out and the new one screws back in. There is a special tool to get them out, but if you have a long enough Allen key, that will work too. The tool is tapered though, which makes it much easier to put the new seat in. Using just an Allen key I sometimes have to use a second thinner key to push the seat forward while turning the bigger key, to get the threads started.

Regarding the comment that the O-ring near the tip isn't needed - I'm not so sure about that. It is there to keep water from going through the threads on the inside of the stem and out where the retaining nut mates with the stem. If that mating surface isn't perfectly flat water can get by it when the stem is in an open position. That O-ring is back up protection, like using a condom even though the woman is on birth control pills. (Hey, it is sort of plumbing, right?)

That O-ring might have a secondary purpose of minimizing wear on the stem and the valve body by keeping the tip centered and avoiding contact between the metal part of the stem and the valve body. It doesn't need to provide much clearance to accomplish this. The O-ring on the older stem looks like it might have shrunk - at least by eye it doesn't seem to extend even to the width of the nearby metal.