Toilet supply leak?

[Techforce]

I happen to work PT in the local home depot plumbing dept and I believe the solution to this problem is a leaky flapper but not 100% sure. My
toilet a (Kohler 1.6g per flush) just is starting to allow some water into the bowl, you can see it coming in from the rim / lip area that usually only pours water in when its been flushed.
You can hear the water line running very very slightly. The shut off valve to the supply line is ok, as soon as I turn it completely closed, it stops. That made me think the
float and valve assy is the culprit, (it looks similar to a 400A Universal Toilet Fill Valve ) so I went in and shot it good with some soapy spray, flushed it a few times and it looks like its diminished a bit but not 100% sure. Could this be the gasket from the tank to the bowl leaking or the flapper? I noticed some water not usually around where the toilet seat screw heads and plastic covers are, on the flat surface where the
Kohler brand is silkscreened onto the porcelan, and thats kinda telling me maybe the tank gasket is leaking? I never remember there being any water there before.

 

[Rickyman]

Replace the fill valve, it’s not shutting off all the way. Might as well change the flapper while you’re at it.

 

[sarg]

Just info on your Fluidmaster 400 valve............ to change them you do not even need to unhook your water supply. Notice the plastic lock ring under the small "tank" that controls the valve on the unit stem. You slip that up and the top of the two piece unit will slide off. They say to unscrew .... but a gentle pull will slide it off when that ring is pulled up.
Turn off the water -- flush out the tank-- pull up the keeper ring --- remove the top portion and replace with a new one --- set the height the same as before and push down the lock ring. There are videos on how to clean them but for me it's easier to replace.
I buy them three at a time and replace the tops about every six months when they get filthy. Your HD store has them for 7 dollars. ( We have water full of sediment )

 

[Techforce]

Thanks Ricky and Sarg for the replies.

I grabbed the float on the fill valve assy and twisted it back and fourth a few times, and the leak stopped. Maybe that dislodged some of the sediment inside the valve for now, so will see what happens. and plan in the future for a new one.

 

[Jeff Handy]

The water by the toilet seat hinges could be condensation, from the cold tank sweating.
Or sometimes a failing fill valve will spray a little bit of water upwards out of the top, which can then escape under the tank lid.
This spray can also come from the bowl refill hose, which is clipped to the overflow tube
It could also be splash out from a vigorous flush.
Or some water could be escaping through the penetration for the flush lever handle.
Or maybe it is just stray piss.

 

[Geofd]

Check the black tube from the fluid master to the overflow tube if it's to long it will siphon your tank it only needs to be an inch or soon to the tank unless it's clipped to the top of the tube then your all set