Maybe someone was nice enough to swap out your engine for a diesel while you were skiing.

 

I think your exhaust manifold is cracked. Like Buzz said as it heats up and the metal expands does it get less noisy after it heats up?

Your o2 readings should be off if its a cracked manifold. Can you monitor your o2's from Ultra Gauge and check against spec?

 

Good job putting up the video.
Thanks..
Now I need to listen to it at home...
sorry you have all this trouble.
But, the video is 1000 words.

 

I took the video earlier, but after the next saga where I snugged up exhaust and not firing at all now and blowing back thru intake, I don't know what to think. I don't think manifold is cracked, didn't see smoke there with seafoam, just where it meets the down pipe.

 

Blowing air back through the intake is a classic symptom of an engine that is out of time. It is of corse sopposed to suck air through the intake. Worn out Timing Chain is my opinion based on the blowing comment ad the fact that it will not fire up now. The video sounds like a metallic rattling sound to me. Slack in the chain. Now why it did not throw any codes is beyond me...

 

Sounds like a exhaust leak to me.
It is common for the exhaust manifold bolts to work loose and the metal gaskets click as the exhaust fly's past them.

 

A few more comments:
Timing chain was done with head gaskets by PO maybe 40k ago
No codes at all
Did seafoam and didn't see exhaust leak at headers, but after header where meets downpipe, heavy on pass side, lighton drivers. At that time, I do not think it as blowing back to intake as I didn't see smoke there, and wa still running.

Any quick way to check the chain? Would that just get uber loose like that with no previous issues? I'm out on biz, but should be ale to mess around later in week. You guys thinking should just drop exhaust after the heades and try to fire bAck up?

 

Just watched the video
Sounds like no oil pressure is getting up to the valve lifters.
Sounds like valve lifters clanking.

Or you have a rocker arm that loosened up and is slamming around.

Hopefully your cam shaft did to crack in half...

 

So you get back in the truck after skiing and it sounds like that.
What if someone switched your oil filter for one which is restricted?

I would change the oil filter and put a good one in like a Wix.
And drop more oil in.

Oil pressure seems way down.

 

sounds like the top end is starving for oil. but before i went any farther I would pull the drive belt off, that emininates all you accessories