Hi,
This has got to be the runner up in the "weird things that happen to my old Benz" contest.
I have recently noticed this weird sound coming from the rear of my '84
300SD. At first I thought it was an empty gas can shuffling around in the trunk, but then I looked at the tach and realized that the quiet, yet deep and bassy sound coming from the back happened only when the tachometer showed 10. Not 9.5, and not 11, but precisely 10.I could make the sound appear and disappear by gently playing with the gas pedal. It's unsettling.
Thanks!
Mia