This is the pulley they installed. Not sure what could cause this to wobble. Im at my wits end haha.

 

I just looked at, and took a crappy video of my 2002 CLK430 (m113 engine) crank pulley...14k miles, it runs ALMOST as true as any of the idler pulleys. On the other hand, I've been dealing with a wobbling crank pulley on my 2008 ML350 (m272) which is based off the m112 block, which is the same as the m113 block...at 183k miles it wobbles just like yours. I put a new OEM pulley, seemed a little better...compared to 5 other m272 engine that all ran true, then put on ANOTHER new OEM pulley, and it still wobbles. I installed both puleys myself , with new OEM bolts, the right tools, proper torque and final degree turn. I also visually inspected the crank snout and key, all looked good. I tested the other new pulley on the bench, and the pulley itself is true. I've never dealt with this before, I can only guess the possibilities are; bent crankshaft, excessive main bearing wear (my 182k ML has the classic m272 thump thump on cold starts) or something with the chain sprocket not sitting flush or true on the crank snout. I'm not going to tear down my m272 engine to find out. If there is any major failures I'll just drop in a lower mileage used engine.

I might say this is normal in the sense that some engine's pulley's wobble...some don't.

 

Thanks for your input. With all the causes you mentioned wouldn’t the car be facing more severe consequences and signals of poor engine health? I mean the engine idle perfect and there pretty much no vibration. No sign of knock either. Previous owner owned the vehicle since around 75k miles or so. I bought the car with roughly 94k miles. When I removed the old pulley that wobbled the same I knew it was never replaced because it was the old OEM part. The new pulley for the m113 is a different shape. To me if the crankshaft was bent or if something was severely off then it wouldn’t have lasted this long. Could be wrong though. The technician said it’s normal and by your explanation it seems normal, so maybe that’s the case? Honestly don’t know. I’ve never heard of this happening on an m113 engine and don’t know what could cause it.