Bowls Not Filling
I installed three 1.28 Drakes with Korky 528T fill valves in early 2009. In varying degrees the bowls in all three no longer fill as high as they once did (and should). In all cases the tanks refill to within ¼” of the overflow. And the refill tubes are properly positioned. Might replacement caps solve the issue?
It's not necessarily the fill valve; it could be something external.
However, it is conceivable that for one reason or another the percentage of water diverted to the refill tube has diminished. The cap does contain the nipple for the refill tube, so your suggestion is one possibility; perhaps the diameter of the orfice under the nipple has begun to narrow from accumulations of one thing or another. It's quite possible that replacing the cap will solve the problem. That it is happening on all three might say something about your water. Can't hurt to try.
First, however, you might just want to service the valve by cleaning it. That's free, although the caps are pretty cheap, too. Someone cited a piece not too long ago from Toto that gives pretty comprehensive instructions on servicing the Korky valve. They make it look a bit complicated; in fact it's easy. Basically, you are rinsing everything. Rather than repeat the instructions, here's the link. Valve Service Instructions Type B valve, obviously, is what you have. Give that a try and let us know how it goes. There's also a video on the Korky web site, but the Toto piece is more comprehensive. Korky 528 Maintenance Video
Originally Posted by wjcandee
On first toilet removed valve cap and cleaned refill nipple. It was somewhat restricted. When this only partially resolved issue, I replaced the refill tube. That did it, bowl refilled like new. Same procedure resolved problem on 2nd and 3rd toilets. Thanks for the help.
My pleasure! It's great when you can bring back the Toto that you loved with a simple fix. Pretty creative changing out the refill tube; I'll add that to my list of things to check when we see that symptom again.