Toilet tank leaks

[Avi]

My toilet tank valve is old and leaking badly. I have lots of condensation on the toilet tank. I bought a new Flowmaster toilet repair kit and when I tried to shut off the water supply valve, it won't close! HELP!!! How can I close the valve? When I turn the valve in one direction, water leaks on the floor along with some black goo... when I turn the valve the other direction the water stops leaking but the valve in the tank continues to leak.

I also notice that I have a large round plastic enclosure about 8" tall that encircles the flapper valve. What is this for? Can I remove it?

Any help is appreciated!!!

[Terry]

Behind the handle for the water shutoff, will be a "packing" nut.
An adjustable spanner can be used to tighten this.

Or a cresent wrench, or pliers.
If that doesn't stop the leak or dripping, you may need to replace the shutoff.

For that, you will need to shut off the main for the home.

The plastic tub is there to prevent too much water from flushing out.
If the toilet has been working fine, I would leave it.
If you remove it, you will need a 1.6 gallon flapper to prevent the entire tank from draining.

[Avi]

I bought a FLUIDMASTER toilet tank repair kit, not a Flowmaster... Generally, are these kits reliable? I sure hope so!

Also, is the height of the overflow tube critical?

[jadnashua]

Each toilet has a design spec as to where the water level needs to be to provide its best flush. This does not mean that it will be a great flush- it depends on the design. If you want it to flush as well as it was designed, you need to adjust the fill level to that point. All fill valves that I'm aware of are adjustable...how it is done is specific to the brand.