Slow leak with all new guts in toilet.

[Mastiff]

Our toilet was having various issues so I decided to just replace everything. I got a fluidmaster kit (not the dual flush) and installed it. I waited a day and felt around under the tank and could feel a little water. There was clearly a slow leak. I'm not sure the brand of the toilet, but it is set up so when you tighten the tank to the base, it has ceramic ridges so you can't make the seal very tight before it bottoms out. I felt like I would have preferred to squeeze the seal a bit more but couldn't because of this "feature".

My real question is this: I pulled the tank off, set it on the sink and filled it with water. It leaks like a sieve around the main valve (the one with the flapper). Should the tank hold water when not mounted to the base? It seems to me that it should, and that the big seal between the tank and base should only come into play during the flush. Is that right? If so, any idea what I could have done so wrong? There's a big rubber gasket on the main flapper valve that I think should be holding water.

Thanks.

 

[Reach4]

One place the leak could come from is at the flush valve. That could be from roughness at the gasket or the big nut not being tight enough.

There will also be a seal under the head each tank bolt. But that does not appear to be the problem since you localized the leak to the flush valve.

Each seal would benefit from some silicone grease between the porcelain and the seal. Sometimes there is some roughness on the ceramic/porcelean that fine sandpaper may remove..

 

[Sponsor]

 

[Mastiff]

Thanks, I'll try the grease trick. It looks like there is a fine crack from one of the bolt holes toward the flush valve. Maybe that's the problem too.

 

[Jadnashua]

A cracked tank needs to be replaced.

FWIW, for most 2-piece toilets, it works much better if you have two nuts and two metal washers along with the rubber one. They need to be installed in this order:
- in the tank, the head of the bolt fits through only the rubber washer
- on the bottom of the tank, a metal washer and a nut tightened up to make the seal
- on the bottom of the bowl, another metal washer and a nut used to anchor the tank to the bowl.

When installed in this manner, you are not relying on the bolts to seal the three points (two holding the tank on, and the tank-bowl seal).

 

[Standardairconditioner]

It would be nice if you can post pics of the top of the bowl without the tank, that narrows down what you may be doing wrong.

For example, vintage Eljer toilers have a special seal that isn't on other typical tank-to-bowl toilets.

 

[Mastiff]

I got a Gerber seal and it seemed to do the trick. It was a bit thicker than the one that came with the kit. I also think the seal was not good at the flush valve for some reason. I loosened it and resealed it with silicone grease and the seal there held as well. Hopefully all is well. Thanks for the help.