water pressure suddenly dies?

When you turn on the hot water in the deep sink in the basement it rushes out very powerful for about 5 seconds, then it violently knocks, and drops to about 1/4 of the pressure. If I open open the tap further the power returns and all is fine, but this violent knock is worrisome. It takes longer than 5 seconds but still seems to occur when only slightly opening the tap, and the knock is not as violent.

The deep sink is very close to the water heater, and it only happens in this location. And on a side not, the water is very cloudy when poured in a glass, but clears up in a minute or two.

whatcha think?

Probably a bad washer in the faucet.

I agree with Kordts... the only other explanation I can think of is a chunk of junk hits a valve or some constricted area then falls back down when the water is turned off. I'd check the faucet washer first.