tank valve - momentary water release

Every once in awhile, one of our toilet tank valves will release a short burst of water. This lasts no longer than 1/4 second. Of course, this wakes us up at night. The water level is at the proper level and is about 1" below the overflow. The float is not water logged and floats the way it should.

Any ideas?

Thanks for any help.

valve

Momentary increases in water pressure will override the water level in the tank and open the valve. A valve without a float ball may help, although it could also respond to pressure changes. A recording pressure gauge might tell you if you are getting spikes, assuming it is sensitive enough to respond to a quick momentary increase. ALL fill valves shut off when the actuator is balanced by the incoming pressure and the force on the closing device. Increasing the incoming pressure, or decreasing the closing pressure will open the valve.

All of our toilets (3) are the same manufacturer and made the same. Only one unit has the problem.

A slow leak will cause the symptoms you describe

Next time you go to bed, put some food coloring in the tank, and see if the water in the bowl is colored in the morning, indicating a leak. Maybe some crud between the flapper and the tank, old, hard flapper, taut chain to flapper, whatever.

Will do. Thanks for your time and knowledge.

L

My time is cheap, and I stole that tip from someone else on this forum, I'm pretty sure, but you're welcome. It should be obvious that this test works any time, not just overnight, so if you're all excited about it you could do it now. Of course, the first flush screws everything up, so you need a long period of inactivity to allow the food coloring to make itself known in the bowl.