I had my bathroom remodeled 18 months ago and I just started having a problem with the shower. Randomly, while the shower is on, I hear a bang that sounds like a rubber mallet hitting the pipes rapidly, and the water coming out of the head pulsates at the same frequency (it's not a pulsating head). The only way to stop it is to turn off the water and turn it back on again.

It started happening when another plumbing fixture would be in use at the same time as the shower, although not EVERY time, and now it doesn't matter if another fixture is in use. It happens maybe 3-4 times per week out of about 14 uses.

My shower fixtures are Pegasus and one of these models are written on my paperwork: 943-799L, 945-086L, 249-397L, 249-393L. I have taken the escutcheon off the single handle and valve to take a photo, if that helps.

Thank you in advance for your help.

Does this happen with hot or cold or both?

The banging sound is most likely a loose washer, or stem, in your faucet. It could also be the pressure balancing device inside the cartridge.

In the posted photo you can see two built-in shut-off valves. (one on the left of the stem and one on the right ). Take a flat screwdriver, close them (screw them in ) and open them again. See if they feel loose. This can be done while water is running through the faucet. See if it helps.

If that doesn't help, install new cartridge.

Let me know how it went... Milo

It happens with both the hot and cold water running, although I haven't been patient enough to just have one or the other running and waiting for the noise to occur since it doesn't happen all of the time.

I did also try your suggestion, Milo, and have screwed in and then back out, the shut-off valves. They did not seem particularly loose. I will see how it goes this week with our normal routine. Since it doesn't happen every shower we take, it may take a little while before we figure out if it's fixed or not.

Thank you for your suggestions.

You would not feel any looseness in turning the valves. It would be the washer on the end of the valve stem that is loose. Could be in in the tub and shower valve or another valve that is open.

Interested to hear what you find. Lee.

UPDATE. So far I have not turned off the water or taken anything else apart, however, I've left this all exposed (with a plastic bag over the hole, to see if it happened again and if I could open and close the hot and cold valves while it was making the noise. It seems the noise is a bit quieter and not as consistent. In the last week and a half, it has only happened three times. The first time, it cleared up on it's own before I could do anything. The second time, it cleared up when I started screwing the cold valve on the right, maybe 1/10th of a turn (not much at all) and it went away. Then the third time, I just turned the faucet to colder, and the noise disappeared, when I went back toward the hotter water, the noise started again and then went away after a few seconds.

I think next, I may call the manufacturer to see if they will send a new cartridge since they have a "limited lifetime warranty". Although I don't know how far that will get me.

Thanks for your help!

You could also try taking the shower head off and running the water full force wide open for a few minutes

Debris in the pipe can do this. Plumbers and electricians when they don't like each other can so some pretty scary things.

When water mains are flushed or broken, rocks and stuff can get through the water lines. These can effectively act like broken valves. The debis hits the scrrn in the kitchen faucet and you get little water. Yu turn it off, it drops a few feet away. You turn it on andyou have water and a few minutes later a trickle.

The other one is the loose washer. This typically makes a pulsating to a vibrating noise and s=depends on flow.

Could be cartridge but more likely a loose washer in integral stop valve. Turn water off, remove bonnet nut, remove stem of stop valve, Tighten washer on end of stem.