Cold Water Shutoff Valve (Apparently) Not Working Properly

Last weekend I replaced the faucets in my kitchen sink. Not consistently, though, sometimes it’s better and sometimes it’s worse. I believe it’s the shutoff valve which is the problem. Reason is that I tested this by shutting it entirely and then reopening, hoping this would improve if it was the problem, and instead it got noticeably worse. Plus, now it won’t completely block the flow of water either. So I think the valve is only semi-responsive to the handle being turned, and the internal part remains in a semi-open position, never fully opening or fully closing.

The valves are about 20 years old. The type of valve is the one shown and described here as “standard”.

Questions are: 1) am I correct that a faulty valve is the culprit, and 2) is there a way to cure it via something simpler than replacing the entire valve?

Shutoff valves always fail.
Why do you care? All they need to do is reduce the flow of water to a trickle, so that you can repair the faucet.
If you really feel that you need to replace them, use ball valves.

Agreed, replace with a ball valve. Those little twist valves don’t last. They should just be a convenience to shut off the water right by the fixture or where exposed such as for a toilet supply. You should have a sturdier valve further down the line also. If there’s a better valve in the basement for instance you could replace it with same kind of simple valve under the sink. If not then get a decent ball valve that will probably last the rest of your life.

In retrospect, I see I left a sentence out of the OP. There should be a second sentence saying that the water flow has been affected, and became much slower than it had been.

You might be able to fix the bad valve, but even if you could…

People often say (with good reason) “If it ain’t broke, don’t fix it”. There ought to be an equivalent catchy saying for this type of situation, something like “You can’t make a silk purse from an economy-grade water valve that sticks randomly and will probably stick again no matter what so what’s the point anyway”.

It has promise, but I think the wording could maybe use some work. :smiley:

When you say ‘valve’ are you talking about the one, above the counter that you use to turn the water on and off on a regular basis, or the shut off valve under the sink that you use to turn the water off when you remove the faucet?

If it’s the ones under the sink, just leave them. As long as the faucet fully shuts off the water, IMO, it doesn’t really matter if the shutoff doesn’t work. In the case of an emergency or the next time you need to do a repair, just go the water main and shut it off there. Personally, I wouldn’t tear the sink apart a second time to replace that valve unless I had a reason to.

If it’s the faucet, the cartridge needs to be replaced.

ETA and if you do replace the valve(s) under the sink, quarter turn ball valves, it’s the only way to go. You can even get ones that look like gate/multi turn valves, but those ball valves aren’t going to break or leak any time soon.

Shutoff valve under the sink, as in the linked picture.

Problem is that it’s not (just) that the shutoff valve won’t turn the water entirely off. It’s also that even when fully open the water flow is very much diminished. So I think the valve is also not fully opening either.

It seems like every time I have a low pressure problem on a faucet, the problem is always the same thing. Have you checked the aerator on the faucet for debris? I replaced about ten feet of pipe leading up to my clothes washer once before I discovered the screen at the washer was blocked with rust flakes from the ancient pipes in this old barn.

Hot water works fine. And again, turning the shutoff valve off and on made a big difference (for the worse).

Yeah, then the valve is broken. It’s been a while, but IIRC, the screw at the bottom (on the inside) that can back off, meaning it won’t shut off all the way and at the same time, when you open it, there’s still a ‘blockage’ in there since there’s a screw and washer.
Technically, it’s an easy fix, shut the water main off, pull the guts of the valve out replace any washers, make sure the screw is all the way in. But I’ve never been good at that kind of thing, plumbing has always been a PITA for me, I’d just replace the valve. They’re cheap and if you get the right kind it won’t/can’t happen again.

Of course to replace the valve you need access to a valve further upstream (whole house shut off?) that works. If that is the case, I would certainly replace the valve. It looks easy enough. Hell, if it were not under the sink it would take ten minutes tops. Under the sink, budget an hour.

ETA: If no shut off valve, live with it or call a plumber.

Thanks a lot, guys!

I replaced the valve. Had to cut the pipe to do it, because it’s soldered on and I’m not getting involved with any soldering. I replaced it with a compression valve. (I bought a new supply line in case the old line didn’t reach, what with the pipe now being about 3/4 inch shorter, but it wasn’t necessary, as the old pipe had some give and could be lifted up a bit.)

Only downside: the problem is not resolved. Might be a bit better, but the flow is definitely much lower than the hot water faucet of the same fixture. I took off the supply line and poked at it with a skewer, but it seems pretty clear, and from what I can tell copper pipes rarely have buildup anyway. I didn’t take the fixture off but I tried to see into the works with a flashlight but couldn’t tell anything.

Weird thing is that when I look at the old removed valve, it does seem that the black rubber gasket is pretty clearly disintegrated, in which case I would expect it would be cured. Unless - is this possible? - a piece of the gasket broke off, travelled up through the supply line and is now lodged in the faucet mechanism.

Anyway, thanks again. One way or the other, I’m learning things about plumbing. You never know when it could be useful.

Not only possible, but likely.

Though it sounds like your supply lines from the shut off valve to the faucet are just barely long enough, the quick check would be to swap the hot and cold water lines. That is, hook up the cold water faucet valve (which has low flow) to the hot water shut off valve (which you know will provide adequate water flow). If the hot water flows through the cold water faucet valve at a low rate, then you know the faucet valve has an obstruction.

Since it’s only on the hot side, it’s probably not in the aerator. Shut the water off and pull the hot cartridge and you’ll probably find the stuff there. You might have to, very slowly, crack the hot water valve so some water pours out and brings the debris with it.

Of course, if you didn’t replace the hot water shut off valve, it will be the next to fail. Probably tomorrow :slight_smile:

So I called up Moen (who made the faucet I just installed) and the woman I spoke to was pretty confident that there’s some blockage in the cartridge. They are sending me a new one.

[IME, Moen stands behind their products like no company I’ve ever seen. A couple of times I’ve had issues with cartridges in the showers and I just call them up and they send me new ones. I’ve been upfront that the fixtures are 20 years old, and I don’t have receipts or anything, but they tell me they guarantee all their stuff for life, period. A big reason to buy their products, ISTM.]

Once she told me that, I figured I’d take a crack at the old cartridge myself, as others have also suggested. Couldn’t see anything.

At this point I’m thinking bring it on. I spent a lot of time going back and forth about how to replace the valve in my particular situation, but now that I’ve figured it out and done it once the next one should be much easier.

I will say that I got some pretty helpful advice on how to go about it from online handyman types, particularly some YouTube videos, and also a fellow customer in the plumbing aisle at Lowes who knew what he was talking about. But the Lowes people themselves were worse than useless. Had I listened to them I would have bought the wrong stuff, and gone about it the wrong way. Fortunately I could tell that what they were saying made no sense and that they didn’t really have a clue.

Update: it apparently wasn’t the cartridge or the valve. The body of the faucet must have been faulty.

Moen sent me a replacement cartridge, and I installed it, to no effect at all. So I called up Moen and they asked me if I had flushed the line prior to installing the new cartridge and I said I had not. (I had thought this was only necessary if replacing a cartridge in an otherwise old faucet, not in new one.) So they said that’s probably the problem but it’s too late to do it now because the new cartridge might have been ruined, so they sent me another one. When I installed that one after flushing the line, the problem wasn’t solved but what was weird was that it changed somewhat. Previously the hot water worked properly and the cold was very slow; now the cold was somewhat improved but the hot flow slowed down to match the cold. (I had been measuring by timing how long it took to fill up a ~36 oz. container. Previously the hot was about 11-12 seconds and the cold ~23 seconds; now they were both ~16-17 seconds.)

So I called Moen and they said OK, they’ll just send me a replacement faucet, which they did. Installed it yesterday morning and all is well.

I’m guessing that there was some obstruction loose inside the body of the faucet at around the point of the spout, and that it could be moved back and forth from blocking the cold to the hot by changes in pressure. Or something.

Once I was busy under the sink anyway, I took the advice of some posters in this thread and replaced the hot water shutoff valve with a ball valve, so I have new and better valves on both lines now.

Overall it was an educational experience. Thanks to all for the advice.