I replaced my old diverter spout with a new one (both Delta), and I've found that the new one will leak water back through the hole in the wall if the diverter is switched off while the shower is running.
If I first turn off the water pressure and then push in the diverter, no problem. So, seems to me that the issue has something to do with the onrush of water when the diverter is switched off while under pressure. I'll just mention that our water pressure is typical (wimpy) for Southern California.
What puzzled me when I was installing this (there were no instructions) is that it doesn't seem to be designed to seal against the wall or prevent water from getting into the outer body of the spout.
Anyone know what I'm doing wrong? Any advice?
I need to finish this up so I can repair the drywall in the downstairs ceiling.