There is a tool that bolts into the starter location and locks the flywheel. That bolt is tightened to 300 or 400Nm so you will need a breaker bar. My engine turned the wrong way while I was trying to get mine off but it didn't hurt anything. I was lucky and found that I could unbolt the pulley from that hub.

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1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500