Driving at about 35 mph my engine suddenly started making a horrible banging noise in speed with the engine. I pulled over and looked under the hood - I couldn't see anything but it sounded like it was coming from the center engine area. It sounded like metal on metal and at idle it was a few times a second. I shut it down, waited a few minutes, started up, and then the noise stopped after a minute or so. Any ideas? Car at dealer now. Many thanks.
Andy
2007 MCS coupe, about 40 k miles.

 

sounds like yr. timing chain tensioner is going south. get that car towed and checked before it fails, causing further damage.