Help! Understanding the basics, Gerber toilet tank water slowly draining

[gtifsport]

Hello, I am not handy but I'm trying to fix that. Here's the situation. I feel like it's an easy solution but I'm just not privy to it.

Model: Gerber 28-170.

Original problem: Toilet was making running noise. No visible leaks, couldn't see water in bowl rising. When I opened the tank, nothing seemed out of sorts but if I pulled this piece of the fill valve up a little, the noise would stop.



I decided to order a replacement fill valve. Gerber 99-023 Fill Valve is the part number. I installed it, everything seemed fine. Water filled to the fill line in the tank, but then about 20 minutes later, I heard the running noise again and this time the tank water was much, much lower.

I'm not sure what the different heights do. I'm struggling to understand how the mechanics of the float work and all that.

This is what the inside of the tank currently looks like. I made some adjustments (winged it) and now the water rises to about an inch above the fill line, but the water continues to drain (very slowly, about an inch per hour).



Should I make any adjustments to A or B, or both, as shown below? Any other advice?


but

 

[Twowaxhack]

Replace the ballcock with a fluidmaster 400a.

No need to get all technical.

 

[gtifsport]

Replace the ballcock with a fluidmaster 400a.

No need to get all technical.

You think this is worth doing even though the fill valve I installed yesterday is brand new? I'm wondering if I did something wrong.

 

[Twowaxhack]

You think this is worth doing even though the fill valve I installed yesterday is brand new? I'm wondering if I did something wrong.

If it’s working, leave it alone.

 

[gtifsport]

If it’s working, leave it alone.

So the problem is that it no longer makes the running noise but the tank is slowly draining.

 

[Twowaxhack]

Replace the flapper

 

[havasu]

The flapper in the picture looks too small. If it is old, they do shrink, but regardless, replace if you are losing water from the tank.

 

[gtifsport]

Thanks guys. I ended up replacing both the fill valve and the flapper (even though I just replaced the fill valve). Both are now Fluidmaster brand and no problems so far!

 

[Twowaxhack]

Ballcock and flapper replacement is like oil and filter to me, I do them together.