HELP, What is This Noise?

I'm rebuilding another 6.0. After getting the engine almost back into the truck, I decided to turn the engine over by hand. I heard a strange noise.

At first I thought it was gear slap on the HPOP so I took that off. It is still making noise.

I didn't have this noise on my last rebuild and don't know what it could be.

Here is a video. What could it be?

https://youtu.be/JAjeayGPo-M

define rebuild.

ive never ever had this noise

CTC DEEZUL said:

define rebuild.

ive never ever had this noise

Click to expand...

Complete rebuild. New heads, machined block, new pistons, stag 2 cam, new lifters, new pushrods, etc...

This engine ate a lifter, so it is a total rebuild. I did a total rebuild on my other 6.0 a couple years ago (it ate a lifter as well).

My brain jumps to either a missing rod bearing or a cap that didn’t get torqued down.

PyroFighter said:

My brain jumps to either a missing rod bearing or a cap that didn’t get torqued down.

Click to expand...

yup.. thats what I was thinking.. thats the sound a rod makes hittin the crank when dropping pistons in...

wanted to confirm the term 'rebuild' was used correctly to see how far OP went...