Sounds like something is rubbing. Per video, the car is shaking at the same frequency as the whoomf whoomf. Is that true? Does it make the same sound in gear (parking brakes on, wheels chocked)? Repeat the test with all the belts off and see if anything changes. Warm the engine up first then remove belts and run no more than 15 seconds since water pump is not turning.

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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