What can cause a knocking sound on the left side of a Detroit S60?

Yeah, even took the compressor off, seems fine. The knock sounded higher up.

The plug had more than the normal fur, it was about an inch worth of buildup. Unless that's normal for these motors?

 

Well it was definitely the bull gear. Not sure how this didn't skip a tooth or screw up timing. The broken ones weren't all broken flush so that's probably what saved it from skipping. All the other gears were fine though. I'm gonna order a recon bull gear from Detroit Deisel Bull Gear : RNC Recon since I've heard good things about them and hopefully get everything put back together next weekend.

I think I'm also going to replace the oil cooler since that's a ton of shavings and I hear that they can get stuck in the cooler and get released later on.

 

There's only 1 gear that rides on this, the adjustable idler. Looked it over very carefully and can't find anything wrong.

 

Yup, already have a new Vibratech in the mail. I'm just debating whether I want to add a balancer as well. Some people love theirs, others said it did absolutely nothing.