CANNOT quiet a Flushometer! Help

[SnakeEyes79]

Hi. I just replaced a diaphragm assembly on a Zurn aquaflush 6000 attached to a toilet. I’ve rotated the diaphragm in every way and still makes this annoying screeching sound right before it’s about to stop the water. What can the problem be? Water pressure is top notch...I know it can’t be too weak. I also was letting out a half turn from the stop screw as I was turning it on and even at low pressures it screeches. I also replaced the vacuum breaker.

 

[Geofd]

Hi. I just replaced a diaphragm assembly on a Zurn aquaflush 6000 attached to a toilet. I’ve rotated the diaphragm in every way and still makes this annoying screeching sound right before it’s about to stop the water. What can the problem be? Water pressure is top notch...I know it can’t be too weak. I also was letting out a half turn from the stop screw as I was turning it on and even at low pressures it screeches. I also replaced the vacuum breaker.
I know with Sloan the plastic cap under the chrome top can cause noises
I just take it out use some heat proof grease and tighten it back down
Your other option is to call zurn

 

[frodo]

what diaphram did you use in the replacement?
If you used a 1 gallon instead of a 3.5 that is the problem

 

[breplum]

Frodo, the diaphrams are universal (even the ones with plastic clog-free/chemical resistant feature).
I know the noise to op is describing. Seen it dozens of times.
Trying a different diaphram sometimes works and sometimes tweaking the supply stop works.
And sometimes we have to just drop in a new assembly. Be sure - if you do this - to get the right GPF for your valve.
The assemblies are universal, you can use Sloan or Zurn.