2006 denali envoy that had the lh6 5.3

Now has gen iv fresh “rebuild” 4.8
btr torque cam/howards springs
headstuds/gaskets
new bearings bottom end
new rings gapped
s366 turbo with feed tee’d at oil pressure sensor
used the 5.3 dod pump/pickup/pan
I “think” 99% sure I plugged the oil pump relief/vent thing and used the 5.3 dod pump (i did this about 3 years ago and just now getting it installed)

fired up had 45 psi on gauge and verified pressure at turbo feed

No radiator or anything yet, so can’t run it too long. I flashed it getting rid of the dod so it would at least run correctly. It has ran probably 10 minutes total, mostly idleing with a few 3k revs here and there. Started to do some base tunes, getting rid of hanging idles, airflow for cam, etc.

Fired it up today and revved it 2500 and heard lifter rattle. Verified oil pressure at turbo feed again, ok. Still showing 40 psi on gauge at idle.
Shut it down, pulled pass side valve cover, pretty dry. Fired it back up, quite a bit of “airy-bubbly” oil coming out of 6-7 rockers, not a steady stream. #1 shot a little at one point then stopped. Def lifter tapping.

Pulled primer plug on side of engine to try to prime, oil poured out. Oil filter full as well.

I dont know where to go next, i really dont want to pull the motor, that sucks in these things.

I have NOT verified with a mechanical gauge, since it has pressure at turbo.
I did NOT prime the system before startup other than lots of cranking and watching for pressure at the turbo and dash gauge.

Seems like it “was” fine, now its not. Pulling the pan is almost as bad as pulling the engine.
Why would it have pressure at oil pressure sensor but not at rockers?
Should i rig up the weed sprayer and try to prime it until I visually get full oil at rockers?

 

That sounds like a cam bearing issue. I would pull the motor and investigate. I have a TBSS, I feel your pain. Not priming it properly probably contributed to the issue. It's a crap shoot just cranking them to get pressure.

 

Pan for oil pressure releave valve is it plugged?
I ALWAYS would "port" the Crankcase area where the Oil Cooler tap is located ?
Lance

 

I misspoke.

Well i pulled the oil pan to verify a couple things.
Which means front 4x4 everything (knuckles/axles/actuator/diff), steering rack & crossover pipe. I swear these things. I only say all that to discourage people from buying these abominations. I have a couple more btw, lol.

1. make sure the plug for the afm was g2g
2. make sure pickup tube o-ring was g2g

So it turns out i installed a LM4 oil pan that didnt have the afm engine. The plug I was previously referring to was the bypass valve that is in the pan of the 05 and newer afm engines…
which this being a gen 4 4.8 with a older non afm 5.3 oil pan does NOT have.

Anyway, found #6 rod cap loose. Not “loose loose” but not torqued. Checked all the rest, I must have missed that one 😞
So inspected bearings, looked fine, but I am worried they maybe lost their crush? Should I re-use or replace? They look new and still fit tight in the rod cap and rod, so I’m thinking they are good. But I am not an engine “builder”, just a “assembler”.

Would this have caused my issue or should I keep going?

 

If the bearing looks ok, it's probably fine. I would be hesitant to reuse the bolts on that one, though. When they come loose while running, they get weird kids on them which may cause stress cracks you can't see. It's a judgement call on your part, but I would put fresh bolts in the one.

 

Were these TTA bolts? It's a good idea to use a sharpie to mark the bolts as you tighten them.

 

yessir, 15ft lbs + 85*

def good advice, normally i go right through them and am focused, i guess i forgot. A marker would’ve saved me alot of headache 👍🏽