I had the exact same problem with my 240D. Seems to be a common problem caused by stuck wafers in the tumbler due to previous owners spraying in "lube" which attracts dirt and, over time, gunk up the wafers. I almost took the drill to it but kept trying the key and it finally turned after 45 minutes. The motion you need is: turn the key back and forth real fast. Also turn the steering wheel back and forth if the steering lock is engaged. Good luck!

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked