Hello all,

We recently discovered a water leak in the ceiling of a closet on our first floor directly under an upstairs shower stall. By happy(maybe happy) conincidence the drywall had already been opened up there from when we had the drain of the shower replaced some years back and we never had the drywall patched.

Doing some inspecting from below it doesn’t seem that the leak is from the drain. It’s dry. That means supply!

I can’t see it, of course.

So, I went upstairs and figured I could maybe see something if I removed the handle and the little decorative plate. I can’t. The hole in the fiberglass insert is only big enough for the plastic threading of the shower valve to pop through and no bigger. There is evidence of water in the interior of the valve (after removing the handle…

Additional context: the mixing valve had been acting up for years. It’s hard to get hot water to come out. Eventually it will but it seems finicky. To the best of my knowledge the cartridge is original to the house (1984).

QUESTION 1: could a failing cartridge be the source of the leak INSIDE the wall (so replacing the cartridge could solve my problem)

QUESTION 2: if answer 1 is yes, it seems i likely have to cut some fiberglass away to get the cartridge out, no? It is a PRICE PFISTER.

QUESTION 3: if a failing cartridge could NOT be the cause of my issue, it seems I have to open up either the wall behind the valve or the fiberglass shower insert, right?

I think I can handle up to and including cutting into the fiberglass or the drywall, if needed, including replacing the cartridge.

If something has the be soldered, I’m gonna have to call the man.

What’s my next step??

Regardless of whether it's the source of your leak, you're going to have to replace that 40 year old cartridge anyway!

Our Moen cartridge was leaking in the same manor you described. The cartridge is behind the handle on ours and I was able to pull it out with the removal tool I purchased. The original was so corroded that it broke inside. A 1/2" drill bit helped with the rest of the removal as it walked back on the bit. However, I do not know how Price Pfister has their cartridge in their faucets.

quote:

Originally posted by RogueJSK:
Regardless of whether it's the source of your leak, you're going to have to replace that 40 year old cartridge anyway!

I watched some videos and tried removing the cartridge and it wouldn’t budge. I think it is the Avante style, and I did remove the lock ring thingy, but there is lots of corrosion. I worry about using too much force and breaking something else.

Gonna spray some vinegar in there and let it set a while.

Replace the entire valve.

15-20 years ago I spent well over a hundred dollars on a Price Phister faucet
for the bathroom sink. I have to replace those damn plastic cartridges about every
18 months. I'll pay top dollar for a quality faucet. I'll search the DIY forums
and see what most people say. Sick and tired of it.

Our Moen fixtures are still working after 28 years (knock on wood). Had to replace one shower’s cartridge a few years ago because it quit supplying hot water, but it wasn’t leaking.

I had a weird leak like you describe in my old house. After cutting thru a cabinet and the wall to access the back of the mixer/handle area of the shower, it turned out there was no caulk or water barrier on the back of the escutcheon.

Every time the kid would take a motel shower, it would leak. As the water spray ran down the control side of the shower in under the escutcheon then into the wall cavity.

But back to your issue. Lowes makes those 8” square cover plates, cut out the back wall of the room adjoining the shower, remove the entire control assy. And then replace the bad cartridge you have.

quote:

Originally posted by MikeinNC:
I had a weird leak like you describe in my old house. After cutting thru a cabinet and the wall to access the back of the mixer/handle area of the shower, it turned out there was no caulk or water barrier on the back of the escutcheon.

Every time the kid would take a motel shower, it would leak. As the water spray ran down the control side of the shower in under the escutcheon then into the wall cavity.

But back to your issue. Lowes makes those 8” square cover plates, cut out the back wall of the room adjoining the shower, remove the entire control assy. And then replace the bad cartridge you have.

Will the valve be soldered in place?

The valve body is usually screwed or nailed into a backer board or cross pieces between two studs. It all depends on who was working that day.

This pic may not be your model, but almost all shower mixers/balancers are like this pic and mounted the same. Depending on the plumber or weird codes the connections could be PEX, copper or steel depending on age.