Hi everybody,
So I was driving my 1984 Mercedes 300TD wagon (~300k miles) and after about an hour on the road I started hearing this knocking noise coming from the engine. I thought it might be the injectors, so I used 2 cans of diesel purge and it still hasn't gone away. I've included a link to a Youtube video so you can hear it yourself. Any thoughts or tips on how to troubleshoot this? Thanks for your help.

https://www.youtube.com/watch?v=iudxlbCRgcY