I have one bathroom sink that makes a loud knocking/vibrating noise when the hot water is turned on full blast - sometimes it starts immediately, sometimes it takes 5-10 seconds to start. It sounds like the pipe inside the wall is vibrating. It doesn't happen with any other fixture in my home, it doesn't happen with the cold water in this particular sink, it doesn't even happen if I turn on the hot water less than full blast. My home is only 13 years old, by the way. Can anybody suggest a possible diagnosis based on this info? Is this something that a handy beginner could possibly fix (I'm assuming not)? If I call a plumber, any ballpark ideas of how much is this repair going to set me back? Is this something that is going to do harm if I ignore it? Thanks in advance for any advice.

A bad washer in the angle stop or faucet could cause the problem and yes it can be a DIY repair. Do you know the make/model of the faucet? We don't discuss pricing here.

Thanks. It's a very basic Moen faucet. Looks like the numbers etched underneath say "4600 27000 64000 74000 84000 series."

I would start with disassembly of the angle stop(unless it's a ¼ turn ball valve) and check the washer in it.

A DIYer to a DIYser

As previously posted, check if your under sink angle stop cut-off valve washer is loose / defective. This can cause vibration in use.

A very common valve in older homes is a BrassCraft valve. If it is NOT a ball valve, the washers used are SPECIAL to this valve. ---- However they are available as a kit in the Orange Big Box store

IF you have this type of valve
Following parts for a BrassCraft valve (If it is NOT a ball valve)

Repair Kit for BrassCraft Stop Valve (All parts in kit may/may not be needed)

Model 9D00088001 SKU 631525

Secure main water supply valve. Open sink valve to bleed water pressure from system. Use pan under valve to catch water. Use one wrench to hold valve body securely and remove valve Bonnet with stem with another wrench. Check / replace washer. When reinstalling valve bonnet, ensure valve stem is "backed off" in open direction at least one turn or so to ensure correct installation of bonnet nut.



Edited 1 times.

You could try turning the hot water valve under the sink off fairly snug and then slowly turn it back on. Sometimes this will push a washer back onto it's stem.

Thanks all for your comments/suggestions. I'll give these a try. I'm at least relieved to know that it doesn't sound like anything too complicated. Appreciate it.



Edited 1 times.