When I reach 45 mph I hear a rattle in the engine that sounds like a marble. But when I am sitting still and rev the engine it does not happen? 150 thousand miles on car.
at 45 mph sounds like a marble is in my engine on 2006 BMW 325i
When sitting still and revving there is no load (or little) on the engine and transmission, also ignition timing problems (they are computer controlled) can also cause a rattling under load. At CarMasters we depending on the problem can install a electronic chassis ear on vehicle during road test or operate on a lift with one technician under vehicle listening while and other is operating the engine and throttle from drivers seat to identify the source of noise/concern