I reviewed the video
A couple things
That doesn't look like a head
with only 4 hours on it
The Valve cover gasket
looks as old as the hills. Any head
I ever send out for work always comes back completely clean...no paint
. I paint
after the job is done and the engine
The pistons show signs of pitting....this is a sign of water
intrusion at some point
I would invest in a Magnaflux Crack detection Kit. You can get them from Graingers.
When you pulled the injectors out was there any rust around any of them?
BTW...I never pull a head with injectors still in.
I would look for cracks around the water
passages or in the bores that the injectors are seated in.
Overall this engine
shows signs of electrolysis
at some point in its life peeling paint, white dusty residue.