View Full Version : G-Max Valve Pulsing

12-30-2012, 02:57 PM
Howdy, all,

I have a Toto toilet with a G-Max valve. Recently, it started.. errr... pulsing on and off. When I remove the blue cap, what I think I see is this: There's water filling the float bowl too quickly. So, the float bowl starts to fill and doesn't drain fast enough (I took out the valve ball to allow it to drain as quickly as possible) and then cuts off the water flow. The water then drains out of the bottom of the float bowl enough to drop the float enough to allow water back in, which then starts to fill the bowl. Repeat this until the tank is filled enough to actually float the float permanently. From what I can see, it's almost as if water is supposed to fill the tank, even going through the float bowl, though... so.. yeah, I dunno what's going on here. Does anyone have any ideas?

Thanks, in advance.


12-30-2012, 03:19 PM
Sounds like you have a Type B valve (made by Korky in Wisconsin). Service it in accordance with these instructions: Toto Fill Valve Servicing Instructions (http://www.bay*******************/images/documents/voretolavallefillvalveinstructions-rev06-1.pdf)

Don't overthink it. Most of the time, just cleaning the parts or replacing the little cap with the rubber parts in it (which cost like $3 at Lowe's) solves the problem.

Here is a simpler video with servicing techniques from the manufacturer:

Sometimes, if you hear it pulsing on and off after the toilet has been sitting for a while, it's not a problem with the fill valve. The fill valve is acting correctly to try to refill the toilet because the water has slowly leaked. Check by marking the water level in the tank with a pencil, then turning off the water to the toilet and letting it sit for a couple of hours. If the water level drops, it's almost always because you need to change the flapper. The Korky GMax flapper is available at a lot of hardware stores (Korky "Fits Toto" GMax Flapper, which is the one made by Korky for your toilet and likely came with it) Korky GMax Flapper (http://korky.com/Flapper2021BP.html). Or the universal Korky 3" flapper is available at Lowe's.

Let us know how it goes.

12-30-2012, 08:45 PM
I'll give this a try.. I should have specified--this issue only happens after a flush. For what it's worth, everything is ok after the cycle of stop-go-stop-go (etc.) end. There's no leaking, and eventually, the float finally can't go back down since the water level's too high to allow it to do so. I'm just questioning whether the inflow water should be going into the float bowl at all to begin with. I can't really test it at 100% since, if I do, the water sprays all over the bathroom...

12-30-2012, 09:59 PM
Yeah. The water goes into the little bowl there. You sound pretty handy, so I would start just by cleaning the thing and making sure that when you reinstall the float, it moves smoothly and freely. If it does, you should be set. If not, change the cap. If that doesn't do it, swap the valve with a 528T (still available in a lot of places and the identical valve to the one you have) or the 528MP (universal replacement valve that you adjust the refill on with a little dial). The latter is available at Lowes for $10.47 (lowe's calls it 528mpk; also available on their web site).

Let us know what happens when you rinse everything off. That will probably do the trick.