Why does a faucet slam off after running.

I have a cold line on one sink and a hot line in another sink. After the water runs for a few seconds, the water "slams" off with a loud bang. I can then keep the valve where it is (not turn it back to the original off position) and turn it again in the on direction and it is fine. The problem just happens from the initial off position to on. They are old fixtures and one of them started after I tried to repair a leak. I changed everything from the shutoff valve, flexible copper tubing, the seat and valve. It does not appear to be house plumbing problem as fixtures upstream and downstream work fine. Any clues? Thanks.
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On Thu, 4 Dec 2008 20:11:08 -0800 (PST), poison snipped-for-privacy@yahoo.com wrote:

When I've had that sort of problem it's been with old fixtures that use screwed on rubber valve seals. The screw loosens and when you first turn it on you get water, but then water gets behind the rubber seal and forces it back down QUICKLY which makes the slam and shuts off the water. When you turn it even farther on you are taking the slack out of the loose screw so it works ok then. After you shut it off you start the cycle over again.
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That would explain why it happened immediately after fixing the leak. The actual seats are metal threaded types (separate from the valve body.) I doubt they came loose but maybe something within the valve body (stem ???) I know on my shower they have screw on washers at the bottom of the stem and maybe that is the culprit. At least I think that's what you were referring to. I'll going to dismantle it tonight. Thanks!
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Hey I see that you flagged your message for deletion. Keep it, that solved the problem for me and I am sure will help others in the future. That was the trick, the washer on the bottom of the valve has a screw through it that was loose. Problem solved! Thanks a ton!
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On Sat, 6 Dec 2008 07:30:04 -0800 (PST), poison snipped-for-privacy@yahoo.com wrote:

I set that years ago. I'm not sure it matters anyway, I think Google and others ignore it and save all messages.
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Not true. Google does not save those posts, and on more than one occasion, I've been "short changed" while searching groups for a answer/solution, because the answer/ solution was given, but the person responding didn't quote the text.
I OFTEN search this and other groups before asking a question.
I've found answers/solutions dating back to 1994 in some cases.
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wrote:

Well, I turned it off so now the messages will live forever.
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COOL!
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Ashton Crusher wrote:

Now we know where somebody got the idea for the piloted valve. (or may have, anyway)
Bob
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wrote:

Exactly!!
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On Dec 4, 11:11pm, poison snipped-for-privacy@yahoo.com wrote:

buffalo ny: "water hammer" your water pressure may be high. on hot and cold water, sometimes an air chamber device will be installed so the rushing water thru the pipe hits the water hammer device to cushion the shock noise. other times, the dead end pipe stubs of the hot and cold supplies are extended vertically above the stops off a tee sometimes hidden in the wall, and the air inside can cushion the noise. if those air chambers are waterlogged they won't work, you can completely drain the house and let the water out of them. that's the cheapest remedy. or you can buy or make inexpensive "Water Hammer Arrestor". search this group for those terms. see also: http://www.naturalhandyman.com/iip/infplumb/infwatham.html theory at: http://en.wikipedia.org/wiki/Water_hammer
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I don't think this is a water hammer problem. There was no problem for 10 years, then immediately after I "fixed it" (I actually did fix the leak but now I have added this problem) it starts doing this? Plus it's only on the cold side on one faucet? Weirder things have happened but I barely even get a knocking sound when the washing machine shuts off. The think the other poster might be onto something.
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