Shower suddenly stops with a slam

[Jerkington]

Problem:

I have a three-handle shower (hot/diverter/cold). When the shower is running, occasionally the water suddenly stops. There is an audible slamming noise and vibration when the water suddenly stops.

When I turn the diverter to the tub, the water comes out of the spigot as normal. When I turn the diverter back to the shower, either the water slams off again or it comes out of the shower as normal.
The one remedy seems to be increasing the water flow.

Other stuff that might matter:

• I replaced the seat washer on the hot/diverter/cold valves recently.
• When I attempted to replace the seat washer on the hot valve, the washer set screw somehow fell out and fell into the open valve. I have no idea where it went, I think it fell into the hot water supply pipe.
• I have Pfister-style valves made by Danco.
• Since changing the seat washers, the hot water gushes out at first (tub or shower) and then the flow drops significantly (but does not stop).

Any ideas?

 

[Jadnashua]

My guess is that the screw, depending on how it ends up oriented, is blocking your flow.

You need to flush that screw out of the line. TO do that, you'll probably need to remove the stems, then have someone turn the water supply back on and look for the screw to come out. Sounds like you only need to do this on the hot line, but if it it made its way past the valve and is now in the riser to the shower head, you might first try removing the head and turning the shower on to see if you can flush it out of there.

 

[Sponsor]

 

[Jerkington]

jadnashua++
It took a couple attempts over a couple days, but just as I was about to give up, the missing screw finally appeared. Shower is working fine even with ultra-low pressure, which was not possible before. Woot!
My guess is that under low pressure, the screw would fall down into the diverter and block the flow of water to the shower. Under very high pressure, the shower was working fine.
Thanks for your help!

 

[Jadnashua]

Thanks for the feedback...glad you resolved your problem.

 

[btozzz222]

Thank you for this old post .. had the exact same issue with the loose screw, and the fix above took care of it.