7.3 Good Oil Pressure at statup, then Zero
 

Hello all,
So if this has already been addressed please point me in the right direction.
Anyway, I just rebuilt my 02 7.3L engine from the ground up. As always, the 1st start up is the most stressful and most always is a hard to start situation. But, eventual it started and sounded like doo doo at 1st but progressively got better. Now it starts up just fund and sounds good. I've worked out all the initial kinks and cleared all the warning lights. But, I've gotten pretty frustrated with the oil pressure reading (dial) on the dash. I know, I know......its just an idiot light and only works for dummies, but it is some kind of reading that verifies the pressure is okay. Anyway, when I start it (and had been a bit cool) the pressure gauge (dial) jumps right up where it supposed to be for about 30- 60 seconds, then goes down to zero. I've checked the voltage on the sensor and its okay, I've checked the oil level in the HPOP resavoir and its okay, I've replaced the sensor and I've even tried the old sensor with the same results. Does anyone have any idea why this is happening? I know that there is oil pressure because without it the engine would not run as good as it does. Also the IPR and ICP reading on my Edge CTS3 look normal. I'm just confused as to my it does that? I've driven it around the block a few times and still, same results. New motor specs below. Thanks in advance for any info on fixing this issue.

All New: stage 2 cam, stage 2 HPOP, low pressure oil pump, bored .20 over, block and heads all redone new seals and all, new bigger turbo, etc.

Lpop
 

Did you install a new lpop also?

Yup, its right there on my list of new stuff installed.

I completely missed it that’s the only thing I could think for the oil pressure dropping like that.

get a mechanical oil pressure gauge to see if you indeed have good oil pressure. You could have a faulty dash gauge or oil pressure sensor.

Sorry guys, kinda dropped the ball in this one. Still having the same problem. Here is an update.

Hello all,
If wrong place to post this, please let me know.

So this is going to be a very odd issue I'm having. Long story short, I've rebuilt my 2002 7.3L and am having issues with the low oil pressure. It starts just fine, runs just fine but there is no low oil pressure at the HPOP reservoir. The Reservoir has oil in it there is just no pressure.
Things I’ve checked and done so far:
-Checked is oil is in reservoir (Yes),
-Checked relief valve that is just behind reservoir (removed it, looked at it, spring is okay, not bent or anything, looks normal, replaced),
-Placed mechanical gauge at top of reservoir, started it up, reads zero, higher rpm’s, 1-3 psi,
-Removed reservoir, checked for cracks, checked screen, all looks normal and clean
-Removed oil cooler to physically check both valves, looked normal, clean, functions good, replaced cooler,
-Attached mechanical gauge to oil cooler port, reads 10psi at idle.
-Removed melling low oil pressure pump, all looks good, no scratches or any damage to mating surfaces

Am I missing something here……why everything runs good, but no pressure at the top and good pressure at the bottom???

Thanks in advance.

Any Body??