Broke 2 new Stems!!

[jamesnoc]

Hello All,
I have a leaky hot water valve in my tub from an old faulty stem. The old stem is a Pfister (9h-8h/c). I purchased a new one, installed it and it stilled leaked. When I removed the new one I noticed the plastic end piece just passed the end rubber seal was broken. Went and bought a second new one and installed it. This time making sure I cleared out all the old stem materials from the piping in the wall. Still leaked with the second new one and upon removing it, another broken plastic end. I thought this was a pretty straight forward fix... (great to be a naive non-plumber) It is my understand that there is not a separate seat for this type of stem. Any thoughts on what I am missing? Thanks for any feedback/suggests.

 

[FishScreener]

Is there a seat that is bad? On some of the stem styles there is a brass seat screwed into the body.

Leaks, and just flow over time can erode the seat, and can damage the seals on the stem when you tighten down against it. Severe cases will result in enough force to break the screw that holds the washer to the stem.

 

[jamesnoc]

I thought it was certainly a bad seat after I broke the first one. However, the pfisher stems parts book does not list specifications for a seat for the particular model stem (9h-8h/c). Whereas for other stems the book provides type/size of seat to be used. Therefore I assume no seat is needed with this particular model stem.

 

[FishScreener]

Shine a small flashlight in there, and see if there is a square, or hex, that would work with a seat wrench. Lower end units, don’t always have replaceable seats, because it adds to the machining costs.

It doesn’t mean they don’t erode. It just means you need to replace the entire body when they do.

 

[breplum]

FishS...that model is a ceramic disc type, and has a black rubber seal at the bottom https://www.amazon.com/dp/B000PSAFMK/?tag=skimlinks_replacement-20
I haven't any exp. with that part. sorry