My C240 started to develop a strange howling noise from the right rear end at about 10,000 miles. The noise would occur when the car is travelling at speed between 64 mph (102 km/h) and 70 mph (112 km/h). The howling sound comes from the right rear end of the car.
The noise would go away if I let off the gas pedal while the car is still travelling between 64 mph and 70 mph. If I re-apply the gas pedal, the howling noise would come back at between those speeds.
I brought the car back to dealer, and they could not detect where the noise is coming from. They could hear it but just do not know the where the noise is from.
I would appreciate if someone here could shed some light on this. Thanks very much for your help.