Tub spout doesnt stick to wall.

I installed a replacement tub spout. Used an allen wrench to tighten up the nut at the bottom, as tight as possible. It works fine when water is turned on, but when I pull the nozzle up to shower, the spout moves away from the wall about 1/4-1/2 inch. I tried waterprrof silicone between the spout and the wall, but when I set it to shower, it moves away from the wall and the silicone starts to foam. Any ideas on how to get the spout to stick?

Thanks
Neil

It sounds like one of two things:

• if it is a slip-on spout, you deformed it enough when tightening the set screw to allow it to leak when there's any pressure (like when you use the diverter to take a shower). Normally, there's no backpressure, so it flows out the spout. The setscrew just keeps it in place and from turning, it has nothing else to do with the actual water seal.
• you damaged the o-ring seals when you installed it. The end of the pipe can't have any burrs or sharp edges, or you risk this.

Also, the pipe in the wall was not anchored properly so the pressure when you shut off the flow pushes the spout out. If you see the silicon foaming, you are spraying water into the wall like a water jet...stop until you fix this or you'll have a much bigger mess. If the pipe is no longer round, you'll have a tough time getting a push-on spout to seal.

Now, if this is a screw-on spout, you probably didn't use teflon tape or pipe dope to seal the threads. That kind of joint can't be made waterproof by just tightening it up without something to seal around the threads (like the tape or dope).

when I set it to shower, it moves away from the wall and the silicone starts to foam

Click to expand...

Sounds like the tub spout seal is leaking.
I would consider installing a Delta replacement tub spout, the kind with the brass fitting that is soldered to the copper pipe, and then the spout is threaded to that.

So........is there any water in the crawlspace under the tub?

spout

What do you mean by "the silicone starts to foam"? Once silicone dries it is basically solid and does not wiggle or foam. In fact, once it is applied properly, it should bond the spout to the wall so it would be almost impossible to remove when you do want to do so.