Weird new sound on yanmar 2qm20

[alctel]

I've noticed my engine making a new noise, it's a sharp, high almost 'rattling', banging sound.

You can hear it from second 3 onwards in this video

https://youtu.be/IbZ_5Bw2G7k

Any ideas what this could be? I checked around the engine and nothing seems loose

[alctel]

I just checked and it does it in forward and reverse as well as neutral.

Throttling up increases the frequency of the noise

[RaymondR]

The first thing I would do is bleed the injectors.

[alctel]

Found the issue - it was the belt.

It looked ok but once I changed it (following up a post somewhere else) the noise went away. PHEW!