No worries. I did promise a small prize, so wanted to offer it, in case you could use it.
As for 'what happened'...
Started the audio recording and put the phone on the windshield / cowl, then started the truck (the audio I posted was edited for brevity). Saw there was oil pressure in about 2 seconds, and stepped out of the truck to listen for any top end noise, etc. (b/c I couldn't get oil up to the lifters, when I attempted various pre-oiling techniques). That was my main concern - top-end oiling. And I had the valve covers bolted on, so I couldn't see, directly.
Things sounded decent enough... started giving myself an 'attaboy'... then I realized I wasn't monitoring the oil pressure to make sure it was stable. Jumped back in the truck, looked at the gauge... and had almost 60lb (!) of pressure with the HV pump I put in (the truck was on high idle, of course). And then...
as soon as I saw that... the needle started dropping. In about 3 sec, it was down to 10lb, and I was reaching for the key to shut it down. But not before the needle went to '0', and the DIC popped up with a warning / chime (either low oil level or pressure -- I have both sensors, and forget now which message displayed. My concern then was getting the engine shut down as quickly as possible.
During this time, I'm thinking maybe there's an issue with the pump cavitating (faulty o-ring install, etc.), and thinking that I was going to have to take the engine apart, again.
Then I heard it... as Moose said... like something dripping onto the garage floor (couldn't hear it w/ the engine running / garage door closed). That's about the time you heard me say "WTF" on the audio file.
Right after that, I looked under the truck... and I had a lake of fresh motor oil under the front of the truck, with about 1min 10sec total oil usage on the hourmeter. At least it was the cheap stuff, relatively speaking (it was only supposed to be in the engine for 20-30min of run-in, then drained out / replaced).
A few seconds later, tracing back where the fluid was coming from, I saw what had happened.
I had previously connected both cooler lines, when I was attempting to pre-oil. No problem there. But - later on, I was attaching the P/S pump & lines underneath the truck, and figured out I'd have an easier time if I disconnected the oil cooler lines from the radiator.
Problem was, I didn't immediately re-attach them, after I got done with the P/S pump / bracket (and I already had the upper / lower fan shroud on, so it wasn't apparent later that I'd forgotten to reattach the line). Plus, I'm sure I'd probably taken a break / quit work for the day & forgotten to reattach the lower cooler line whenever I started up work again).
(As an aside... If you've ever watched TV shows like 'Roadkill,' you know that the guys there often whiteboard a checklist of things to take care of, when they're bringing a car back from the dead. In retrospect, that's a good plan, and I will probably do it myself, the next time I do a project like this. I'm used to taking a cursory look, seeing 'no extra parts' lying around or in baggies, and deducing that I'm finished. Well, that didn't work, this time.)
So... I got to see just how efficiently the new oil pump could evacuate all the oil from the engine... and given that the lower cooler line (engine outlet) was the 'end of the loop', as it were... all the oil went from sump, to pump, (& through the engine,) and then to
dump. Within a minute.
So now I had about six quarts of oil on the floor, heading toward the garage door (mine is built on a 6% incline, for drainage, etc. -- as most probably are.) Quick like a bunny to the kitty litter & shop towels. Then curse myself for not being more careful, and expecting that I might have spun one or more bearings. And not collecting my tools that were on the floor, etc., before starting the truck. Needless to say, I had a helluva mess going on, and thinking that I probably screwed the pooch.
Thankfully, I must've gotten
some oil to the bottom end while I was pre-oiling, and the oil & assembly lube that I applied to the top end parts must've kept things intact, there. A couple of days later, I got the courage to refill the sump, make sure everything was connected, and fire up the engine (no desire for audio, this time). To my surprise & relief, it started more or less quietly, and quickly got quiet to the point where all I heard was the injectors clicking within about a minute.
With the (new replacement) oil staying in the engine, oil pressure with the HV pump is about 'two clicks' more than with the old pump (so about from 38psi, to 42psi, according to the dash gage -- which we know isn't calibrated accurate, but it's fairly close). But it was higher than that, the first few times I started the engine. Took about a week, I'd say, for the needle to move from about 56-58psi, down to its current ~ 42psi, at high idle / cold viscosity. I have no idea why that is. But given that I had good pressure with the old pump, I didn't want to go with a HP / HV pump -- and it looks like I made the right choice, in retrospect. Yay me.
So... that's the 'how' of why all my oil drained out of the truck, at first startup.
Next update -- break-in of cam & valve springs; 1st drive; initial impressions.