Water pressure issue in tub faucet

Hi Folks... For my bathtub faucet, the hot water flow is very light and when I turn on the cold water, I get a very loud pulsating sound from the wall (obviously the pipes, etc.) What might be the cause of this and do you have any suggestions on repair?

Here's a video of the problem: http://www.youtube.com/watch?v=o0XnxMPX2Uo

Thanks for any suggestions/tips/help!

[video=youtube;o0XnxMPX2Uo]http://www.youtube.com/watch?v=o0XnxMPX2Uo[/video]

Normally pulsated is caused by fluttering of the valve.
Loose washer or junk bouncing back on forth in the valve.

Low water pressure, junk in the valve.

Remove stems and try to flush out.
If that doesn't work, you may have to go to the pipes below the faucet.
They could have installed shutoffs below, and they could be clogged or have a loose washer.

I serviced one home that a Seattle Plumbing company had installed, ( I can't name them, I have a nice letter from their lawyer) I had quite a time flushing out all the crud before everything worked.
Lucky for them I know how to fix their stuff though.

Ah, crud.

Thanks for these tips... I have an access panel that when opened, I see the values... no shut offs though... I will shut off the water and take a look to see what 'crud' I can find... and then reconnect to make sure there are no loose parts...

Any suggestions on best methods for 'flushing' the crud?

Thanks!
Dan

Have someone at the shutoff with a cell phone,
Have a way to divert water into the tub, your hand, some plastic, something.
Otherwise, it will shooting up to the ceiling.

Thanks Terry! I appreciate the tips. I will try this tomorrow and see how it goes.