My 230e has developed a high pitched noise.whine from gearbox only when hot and only when in neutral or park. This transmits along oil cooler pipe and high frequnecy vibration can be felt on pipe. Have taken to mercedes mecahanic who after consultation with gearbox engineer changed the "pressure unit" in the gearbox. This has not solved problem and the mechanic suggested to wait and see as seems fine while driving. Car only travelled 62,000 Km. Seems to be very uncommon problem. Any ideas as to other possible causes??
Thanks