How to Repair a Shower Valve Stem | Ask This Old House

all right Pat what’s going on in here well we’re having a problem with the shower when I think I have the temperature all set all of a sudden it starts getting cold okay it gets colder yeah yeah and this kept happening and I was trying to figure out what was wrong and decided that when you turn the hot water on it starts disappearing you see it nothing okay eventually it’s gonna drift off again – and there it goes getting less and less that’s just a boat off all right believe it or not I have seen this before and we’re going to fix this B oh really that’s great it starts by me shutting off the water so what you’ve got here Pat is called a free valve there’s a hot water stem right here a cold water stem right here and the diverter is in the middle that helps determine if the water comes out of the spout or the shower and I think you have a problem right here in the hot stem now we’re going to work on the working parts of this I have to expose the handle and the escutcheons on these any time you look at these handles you realize they have to be attached somehow to get out the screw you have to pry off the index from the end a good tip is to make sure you have something in the tub drain so you don’t drop it right down the drain all right so there’s that and what’s behind here is a Phillips screw so I’m going to loosen that counterclockwise and now when I get it out a little bit I want to pull the handle towards the screw and then keep on loosening so I’ll pull that handle right off the stem sometimes it does not come easy oh so these are not original handles this is this pretty ingenious bushing that was designed to fit onto any number of stems in here and will let you have any style handle you want it alright so that means that the shower valve itself is older than these handles so now what I have to do with one removed I can now remove the escutcheon right here and this is the cover plate all right so now that exposes the stem unit right here there’s a stem and there’s a bonnet right there now I need to back this out of the valve that’s inside the wall now in some cases I can use a pair of pliers because this nut right here is outside of the wall so I could loosed it right like that but they also make a set of socket wrenches all different shapes and sizes for the different valves that are on the market I’m going to use that now with a pair of pliers I can loosen it there we go okay all right Pat sir here is your stem unit this is the bonnet right here I put the handle back on for you so now you can see what happens when you turn the handle this stem unit goes in or it goes out because it has threads inside here now it’s pushing down a washer right here at the end against a seat that’s inside the faucet so the first thing I notice is this washer is not installed correctly see it’s rising on one side so that’s one of the issues but I don’t think it’s the whole issue the other is this if I’m going to hold this you watch what happens right here when I try to move this handle do you see right here how there’s a lot of wiggle it shouldn’t be like that this is a brand new stem right here I’ve cut it apart so now you can see the male threads and the female threads right here when I turn it goes up and goes down but you’ll notice if I wiggle it there’s no slop at all it’s really tight as these are milled perfectly these ones have probably worn out now what happens is that particularly with your case where it’s a hot water stem imagine what happens you’ve opened up a little bit and now super hot water comes up from the basement and what people don’t realize that any metal when you heat it up it gets expanded it gets longer so now you’ve opened up like this the hot water touches that brass stem right here and it actually gets longer what does it do it really just closes off the put the opening now you open a little bit more it just does it again because it keeps expanding because there’s so much slop in it so I think it’s happening is that the threads that just worn out on the soil unit so we’re going to have to replace it but I just happen to have the right units with me and they’re good good all right and before I install the new stem I also want to replace the seat now this is the part that the washer sits against that goes inside the valve body which is inside the wall and make a special wrench for that it’s called a seat wrench it’s basically a tapered allen wrench designed to be able to go right inside that seat and back the old one out and install the new one let’s see how we do come on baby okay yep there we go here’s

the old one right there okay looks like it was ready for replacement all right so I want to put a little bit of pipe thread sealant on these threads and then try to get it threaded in without losing it inside the wall okay good so now we can install our new stem unit with its bonnet there’s a special gasket right here already and now we just tighten it up loop and then snug it up with the same wrench all right so right now you’re hot sighs completely rebuilt the stem and the seat but because I have the Parsee because I like you we’re going to rebuild all the rest of it the diverter and the cold all right great a little bit of plumbers product will seal those sketches against the tile we’re going to reuse those bushings from the old stimulus to make sure we can install those handles again give it a try hot water is on and it looks like the hot water is staying on fantast alright sure thank you