190D 2.5 Turbo harmonic balancer wear
 

I thought it was the crank seal that was leaking, but it looks like the balancer itself is what was causing the issues. I'm guessing at some point the seal went bad and someone waited too long to change it out, so it started wearing on the hub. It looks like a new balancer is $600, which is more than I'm willing to pay. Are there any other options here, or should I just throw this engine away?

https://i.imgur.com/L5TqjJQ.jpg

Speedi sleeve

I have a good used one in a parts bin, PM me.
Off a '91 300D 2.5T, didn't leak.. can send pics/part # to verify the interchange.

After doing some reading, that sounds like what I'm looking for. Thank you!

The part exhibiting that actual wear, the grooving; is the hub to which the harmonic balancer is bolted to, it's a separate part.

The hub itself is available for about $75 from online dealers, the Speedi-Sleeve is available from places like AutoZone for about $50.

I did this a couple years ago and I think I used the Speedi-Sleeve SKF 99177, that's for the restoration of a 45 mm outside diameter which I'm pretty sure the hub is. I obtained the sleeve from brakepadwholesale.com for for about $24 plus $9 shipping back then.