Faucet piece question

[Oyeve]

I have a leak in my bathroom sinks cold water. I turned off the mains as much as possible (Doesnt really shut off completely) and took apart the piece that is under the handle. I removed the shaft part and the part that is causing the leak is a hard rubber washer kinda thingy but 10x thicker. It looks like a Tums pill but hard black ruber. I have no idea what it is called. Anyone know what im talking about?

 

[OILFIELDTRASH]

Take it to a plumbing supply store they'll get you a new one. Faucets IMO aren't usually worth fixing unless its a high end one. By the time seals go out the faucet is usually used up and you're just buying a little time.

 

[Oyeve]

Take it to a plumbing supply store they'll get you a new one. Faucets IMO aren't usually worth fixing unless its a high end one. By the time seals go out the faucet is usually used up and you're just buying a little time.

Well, the problem is that the water mains are in the kithchen and the cold water does not shut off completely. When I work in the bathroom sink I turn off the main valve in the kitchen and I run the cold water in the kitchen sink which still has a little cold water coming out and it aleviates a lot of pressure. In the bathroom I remove the cold water handle and the shaft and water will come. Its not enough to flood over as it just goes into the sink. I can leave it apart long enough to replace the part but for me to replace the faucet means I have to disconnect the piping which I have done dozens of time before but this apartment has no water valves for the bathroom IN the bathroom, its all in the kitchen and does not fully shut down the water. My apartment building was erected in 1946 and has 100s of apartments in it and I doubt I can convince the co-op board to turn off the building water. Thats why I was trying to find out the name of this part.

 

[iamwiz82]

If the valve isn't shutting off you should replace the valve as well.

 

[chusteczka]

Yes, that is called a disk. The disk moves to create a seal with the seat.

The valve disk for a residential plumbing faucet typically being in the shape of a frustoconical washer composed of a resilient rubber.

Take the whole valve stem with the rubber disk to the hardware store. They will have replacement parts there. Depending on what is available at the store, you can replace just the disk or the whole valve stem.


Edit:
The water leaking past the main shutoff valve(s) into your apartment may be too much for you to be able to repair your valve. In this case, you would talk to your apartment management, they would schedule a professional to replace your main shut-off valve(s), and the building water would be secured and depressurized during this time. The main shut-off valve is the responsibility of your apartment management.


Edit2:
Depending on the faucet style, it could be the seat you are looking at.
http://www.diyadvice.com/diy/plumbing/faucets/two-handle-disk-diaphragm/

There should also be an additional water stop valve under the bathroom sink.

Google.com - Faucet repair

 

[Oyeve]

Edit:
Edit2:
Depending on the faucet style, it could be the seat you are looking at.
http://www.diyadvice.com/diy/plumbing/faucets/two-handle-disk-diaphragm/

There should also be an additional water stop valve under the bathroom sink.

Google.com - Faucet repair

Bingo, the part I need from this diagram is called a "seat". Mine is around that thick but the hole in the middle is much smaller and is installed to the shaft via screw. And no, no valves under the sink. That was the first thing I checked. Thanks!

 

[DrPizza]

Sounds like you're describing a faucet washer. They make them flat like this, and also beveled. http://plumbing.hardwarestore.com/51-286-faucet-washers/flat-faucet-washer-assortment--654237.aspx

Unless I'm mistaken, the seat is the inside part that the washer presses against. It's possible the seat has a slight chip on the edge, which leads to a quickly worn washer, and subsequently, dripping. There is a tool for reaming the seat smooth again. You can also remove the seat (allen wrench) and replace it.
http://www.amazon.com/WG-11637-Fauce.../dp/B000DZKTN0
http://www.amazon.com/Danco-Corp-9D0...ds=Faucet+seat

There are other types of seats, but this seems to be the type you are describing in the OP. telling us the brand would make a difference. Someone above mentioned that they wouldn't repair a cheap faucet, they are "used up.". They probably gained that opinion by only completing half of the job. Those washers don't just wear out (normally) with the seat still being in good condition. Do half the job, and you'll likely have to do it again in a month, making you think you wasted your time.