I have a 1994 Honda Civic DX. Recently, I've noticed some noices coming from under the hood. It was a clattering sound at first, which I thought was coming from the top mount of the engine and sounded like a rocker was loose. Then it got worse. When I go to a stop light and hold the brake, it starts to have a knocking sound. When I let off the brake, it goes away. I have no idea what this is. Any help would be awesome.

 

Does it make any unusual noise when driving, or just when stopped? I assume it's automatic. In that case it seems to be idling at too low an rpm. The usual cause of that is the IACV (idle air control valve) being clogged up.