No it was late when he did the alternator swap, the battery light was off when the car started and everything seemed like it was good to go

Two possibles for the motor noise ,air cleaner ,motor mounts.

The stock air cleaner was ripped out by the previous owner, and the motor mounts are new. It's a rattling sound, it rattles in 2 second intervals every 5 seconds at idle, and gets much louder and a little bit more frequent as I rev the engine. It sounds like it's coming from the bottom pass side of the engine

Late not good excuse. Takes 30 seconds to check. Shame on Colin. Battery light off does not guaranty good charging voltage.

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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

Do you have a battery drain? Try to measure it with a amp meter. Or disconnect the battery every time you turn off the car. See whether it will restart again.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.