Hi. I have a Demio with about 125K miles on the clock. It's developed a random loud knocking sound once the engine has warmed up and idling. When idling the knocks come at about 6 times a second but not regular. They don't get any louder from revving the engine - either that or other engine noise masks the knocking. After the revving the knocking disappears momentarily, like a few seconds, then returns. It's loudest near to the pulley end of the engine. Can't attach mp3 so it's here: http://www.mediafire.com/file/fevcus...attle.mp3/file Would some kind person suggest what the problem could be? Many thanks. Dan