Gerber Toilet has a mysterious tank leak, i think?

[carriagehousereno]

I have a gerber toilet in one of my rental properties, it appears to be in good condition but I can hear it filling the tank periodically when it isn't even being used. I replaced the flapper thinking maybe it was leaking, still was filling periodically. I replaced the fill valve thinking maybe it was faulty, I've replaced all the gaskets and internal parts that are replaceable and it still is filling periodically. For the life of me I can't find any signs of external leaking, could it be leaking internally somehow? This is my last resort before just replacing it with a new toilet. Any ideas?

 

[Reach4]

In troubleshooting, one way is to turn off the supply stop valve at the wall, and see what the water is doing. If the water continues to drop, then the problem is in the flush valve, and a flapper leak would be the common thing.

If the chain is a little tight, that could make a new flapper leak a bit. Some debris or deposit on the valve seat could make the new flapper leak.

If the water level stopped dropping midway, a rare crack in the overflow tube could explain that.

If the water stays within an inch of the overflow, the refill tube might not be elevated by a clip. If the refill tube goes down the overflow tube, the water can siphon down the tube, causing the valve to cut on to refill the lost water.

 

[Sponsor]

 

[Sylvan]

Shut the water supply to the tank and look at the water level.

Check it a few hours later and open the fill valve . This will tell you if water is seeping past the flapper

Then check your refill tube water supply especially on a 400A to make sure the fill tube is above the over flow tube to prevent the water from dripping

You can also use instant coffee or a dye and see if it shows up in the bowl

 

[carriagehousereno]

Thanks for the tips, was not aware of the siphoning issue or the possibility of a crack in the tube. I'll go through this process tomorrow when I'm at the property to see what is going on.

 

[Chris Rooney]

I have had a time of it- No markings on the Gerber toilet tank other than Gerber A 1985 or 86(hard to read). I rebuilt with Fluidmaster products stating ok for Gerber but a different gasket was needed. Ordered Tank to bowl gasket 818 515. I too have found the gasket to not quite fit the underside nut.(others have said similar). In spite of trying to get it all just right and seated- The toilet continued continued to have a significant leak on the floor. Back to research but couldn't find the info on this toilet. I took the tank off for the 4th time, Cleaned regions with a Brillo pad to remove any hint of old residue or calcium. I used silicone grease (DON'T use Vaseline- it will dissolve gaskets) on all parts- tank bolt washers and more importantly the tank bowl gasket. I put it around where the nut interface and tank interface was as well as the toilet interface. I noticed that there was a slight up turn in the rear of the toilet porcelain where the gasket would rest. That kinda looked like it could be a potential pinch or spot for extra stress on the gasket. I took the flapper off so I could get as near perfect a line of vision as I lowered the tank into place, reconnected everything and -Voila!, no more leaks!.