Replaced Toto 528 Cap and Now Hammering?

After reading through here on leaking fill valves [water would continue to run ever so slightly after flushing], I followed the directions and removed and cleaned the unit. I found a piece of solder stuck in the tube and figured that must have been the problem and thought while I was at it I would replace the cap [528].

Now after flushing the water line will hammer until the water level is reached and the valve shuts off. So the leak is fixed but the hammering is obviously no good. I pulled the until completely apart and put it completely back together and the hammering continues. Suggestions?

Is the valve at the wall all the way open?

Also, you might want to disconnect the water supply hose and make sure there's nothing in there that dropped down when you removed the little piece of solder.

wjcandee said:

Is the valve at the wall all the way open?

Also, you might want to disconnect the water supply hose and make sure there's nothing in there that dropped down when you removed the little piece of solder.

Click to expand...

The fill valve is all the way open, but I did not disconnect the water supply line yet, so I will do that.

To clarify the hammering is durring the last 1/2" of fill or so of the tank. Prior to that there is not any concern. Just a thought, does the ID of the flex tube from the fill valve to the fill tube have any impact? I ask as I grabbed one off a FluidMaster that was laying aroung that was new vs. the original one from the toto/korky which is about 10 years old.

Multi-turn shutoffs (verses say a 1/4-turn ball valve) have a washer, and at certain flow rates if the washer is worn, the screw is loose, or there's something caught in the line, can make some nasty water hammer occur. I'd also check my household water pressure. You can get some noises on things (especially toilet fill valves) if the pressure is excessive (anything about 80psi requires reduction per codes). The older valve, because it was leaking, provided a release from high pressure. Now that it actually can seal, it may be complaining about high pressure...it's easy enough to check.

Maybe try switching the fill hose with the old one and see if it makes a difference.

Also, if that doesn't do it, check where you reattached the float to the new cap. Sometimes, it's possible to get it in there a little off-kilter. It should click smoothly into place and then move freely and smoothly when you touch the top of the arm of the float that sits on the cap. From your description, the hammer is being induced by harmonics that are occuring when the flow is starting to be restricted (the last half-inch or so of the fill process). The reason I said to try going back to the old hose is that the first thing you look at when diagnosing a problem is "what has changed from when it worked fine?" If that doesn't do it, then the most likely sources of hammer are going to be weird flow at the wall valve like Jim mentions, or the flow right there at the shutoff point of the Korky, and a sticky float might do it. You might look at the Korky video on servicing the valve to see if they do it differently than you did it.

Let us know if any of this fixes it. Sometimes, we throw the stuff out there and the most-unlikely potential cause turns out to be it.