How to troubleshoot strange noises coming from my Audi 80 engine?

I've recently noticed that my Audi 80 is making strange noises from the engine. It sounds like a knocking or clicking noise. It's not a constant noise and only happens sporadically. What could be causing this and how can I fix it?

It's possible that the engine is low on oil or the oil needs to be changed. Check the oil level and if needed, change the oil and filter.

Another potential cause could be a loose or worn belt. Look for any visible signs of damage or wear on the belts and tighten or replace them if necessary.